Enhancing optical properties of transparent wood by plasma modification

Enhancing optical properties of transparent wood by plasma modification | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Enhancing optical properties of transparent wood by plasma modification Igor Wachter, Tomáš Štefko, Jozef Martinka, Peter Rantuch, Lenka Blinová, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7426252/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Mar, 2026 Read the published version in Cellulose → Version 1 posted 4 You are reading this latest preprint version Abstract Transparent wood is a promising sustainable alternative to glass in construction and technology, but its fabrication is often hindered by the use of harsh chemicals, high costs, and scalability issues. This study introduces a novel, solvent-free method for producing transparent wood by employing a volumetric plasma modification technique. Balsa wood scaffolds were first bleached and then treated using an Atmospheric Discharge with Runaway Electrons (ADRE) plasma, which uniquely modifies the entire material volume, enhancing compatibility with an infiltrating acrylic resin. The resulting plasma-treated transparent wood demonstrated significantly improved optical properties, achieving a high transmittance of 91% at 550 nm, compared to 72% for untreated samples. This enhancement is attributed to improved polymer infiltration and reduced light scattering at the wood-polymer interface. By eliminating the need for hazardous organic solvents and complex chemical treatments, this plasma-based approach offers a more cost-effective, scalable, and environmentally friendly pathway for fabricating high-performance transparent wood. This innovation advances the potential of transparent wood as a practical material for energy-efficient buildings and other advanced applications. Balsa Modification Optical properties Plasma treatment Transmittance Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction According to a 2022 IPCC report, Earth is predicted to reach 1.5°C of warming within the next two decades, necessitating drastic reductions in carbon emissions to avert an environmental catastrophe (Pörtner et al., 2022 ). A critical focus must be placed on sustainable growth and reducing reliance on fossil fuels, which are the source of most of the 36 billion metric tons of CO 2 emitted globally each year. The construction industry is a significant contributor, accounting for 37% of all CO 2 emissions in 2020 through its activities and materials (USGCRP, 2017). To mitigate this impact, it is essential to design high-performance, multipurpose building materials. While glass is widely used for windows, its brittleness and energy-intensive manufacturing are considerable drawbacks. In contrast, wood offers superior mechanical strength, natural abundance, and renewability (C. Chen et al., 2020 ). This has driven the development of transparent wood, a transformative material positioned as a sustainable alternative with advanced applications such as multi-functional windows (Mi et al., 2020 ; Mishra et al., 2020 ; Qiu et al., 2020 ), integrated solar cells (Y. Li et al., 2019 ; Zhu, Li, et al., 2016 ), thermal energy storage systems (Y. Li et al., 2019 ; Montanari et al., 2023 ), and even load-bearing structural elements in modern architecture (Fu et al., 2018 ; Karľa, 2020 ; Katunský et al., 2018 ). Wood is a porous and fibrous composite of cellulose, hemicellulose, and lignin (Jin et al., 2017 ). Its natural opacity is primarily due to lignin, whose chromophoric compounds—such as carbonyl groups, biphenyls, and ring-conjugated double bonds—absorb light across the visible spectrum (Sadeghifar & Ragauskas, 2020 ). To achieve transparency, a two-step process is conventionally employed. First, the lignin is removed or bleached from the wood scaffold through aggressive chemical delignification using agents like sodium chlorite (NaClO₂) (Zhu, Song, et al., 2016 ), sodium hydroxide (Y. Li, Fu, Rojas, et al., 2017 ), or hydrogen peroxide (H₂O₂) (H. Li et al., 2019 ). Second, the remaining porous cellulose scaffold is infiltrated with a polymer that has a refractive index matching that of cellulose (n ≈ 1.5), such as PMMA (Y. Li et al., 2016 ), epoxy (Zhu et al., 2016 ), or PVA (Tang et al., 2024 ), to create a transparent composite. However, despite its promise, the conventional fabrication of transparent wood presents significant environmental, economic, and performance challenges that impede its widespread adoption. The delignification processes rely on chemicals that are often toxic and environmentally harmful, creating substantial issues for their safe disposal and potential reuse (Simelane et al., 2024 ). These intricate and harsh chemical treatments also contribute to higher production costs compared to traditional transparent materials, hindering scalability (Hai et al., 2025 ). Furthermore, the delignification process exposes hydrophilic hydroxyl groups on the cellulose scaffold, leading to poor compatibility with the hydrophobic polymers used for infiltration. This mismatch can cause interface gaps and compromise the composite's optical quality and long-term durability (Y. Li, Yang, et al., 2018 ). Collectively, these burdens undermine the inherent sustainability of using wood as a green building material. Plasma treatment is a versatile and efficient (surface-modification) technique that can be used to enhance the properties of cellulose-based scaffolds. The process involves bombarding the material with an ionized gas, which breaks chemical bonds and creates highly reactive sites on the cellulose surface without altering its bulk properties (Nisoa & Wanichapichart, 2010 ; Rifathin et al., 2025 ). This activation can be used to introduce new functional groups, such as hydroxyl (-OH), carbonyl (C = O), and carboxyl (-COOH) groups, which increase the surface energy and wettability of the cellulose (Alanis et al., 2019 ; Chiper & Borcia, 2023 ). This modification is crucial for improving the scaffold's performance and compatibility with other materials. The current study introduces a novel and effective method to fabricate transparent wood (Balsa wood - Ochroma pyramidale L. ) by employing a volumetric plasma modification. Whereas conventional plasma treatments are limited to surface modification, here the principle is extended to treat the entire scaffold. This strategy circumvents the need for harsh chemical reagents and solvents traditionally used for delignification, thereby addressing key challenges in cost, environmental safety, and scalability. By demonstrating that plasma treatment can effectively improve transparency and interfacial compatibility, this work provides a (promising new pathway) toward the practical realization of high-performance, sustainable transparent wood materials for smart building and advanced technological applications. Materials and Methods Materials and chemicals Longitudinally cut balsa wood ( Ochroma pyramidale L. ), with density of 0.15–0.17 g.cm −3 , was procured from JAF Holz Slovakia Ltd. Samples measuring 50 × 50 × 1 mm were prepared for various tests. FTIR analysis, colorimetry, UV-VIS analysis, and thermal analysis were performed on a 1 mm thick samples (other dimensions were determined by the analysis itself and instrument requirements). Sodium silicate (Na₂SiO₃, 36/38 °Bé), sodium hydroxide (NaOH, p.a. <99%), magnesium sulphate (MgSO 4 , p.a. 98%), ethylenediaminetetraacetic acid (EDTA, p.a., <99%) and hydrogen peroxide (H 2 O 2 ,p.a. 35%) were purchased from CentralChem Ltd. Deionised water was prepared directly in the laboratory. (2-hydroxyethyl)-methacrylate (97%), (hexane-1,6-diyl)-diacrylate (80%) and 2,2-Azobis(2-methylpropionitrile) were purchased from Sigma-Aldrich. Dodecyl-methacrylate (97%) was purchased from Avantor, Inc. All the chemicals were used as received without further purification. Lignin Modification The lignin modification procedure was originally proposed by Li et al. (Y. Li, Fu, Rojas, et al., 2017). Balsa wood samples were submerged into a lignin modifying solution at 70 °C. The solution was prepared by mixing chemicals in the following order: deionized water, sodium silicate (3 wt%), sodium hydroxide solution (3 wt%), magnesium sulphate (0.1 wt%), DTPA (0.1 wt%), and then H 2 O 2 (4.0 wt%). Subsequently, additional 35% H 2 O 2 solution was gradually supplemented over the course of a few hours until the samples became completely white. This continuous addition was necessary to compensate for H 2 O 2 decomposition during the reaction. The samples were then replaced to a deionized water bath for 24 h to let the residual chemical leach out and diffuse. Plasma treatment To modify the entire volume of the bleached and dehydrated wood samples plasma treatment was used. The Atmospheric Discharge with Runaway Electrons (ADRE) plasma was used. It combines the advantages of low-temperature plasma at low pressure and plasma at atmospheric pressure. One of the main features of ADRE plasma is the creation of a large number of fast electrons in the region of a given power. These electrons acquire energy of up to several tens of kiloelectronvolts (keV), while the average energy of electrons in other discharges reaches the order of several electronvolts (eV). In terms of the effectiveness of the impact on wetting and other properties of materials, ADRE plasma significantly surpasses all existing atmospheric discharges and is close to discharges generated at low pressure almost at the vacuum level. This allows processing the material at high speed, and the possibility of including ADRE plasma equipment in a continuous technological process. To modify the entire scaffold of the bleached and dehydrated wood samples, plasma treatment was applied using Atmospheric Discharge with Runaway Electrons (ADRE) plasma. This discharge produces a high number of fast electrons (reaching tens of keV), surpassing conventional atmospheric plasmas in effectiveness for surface activation. The plasma apparatus comprised: (i) a (computer-controlled) high-voltage power supply (max. 50 kV; Kamea s.r.o., Piešťany, Slovakia), (ii) a working chamber equipped with two parallel planar electrodes (20 × 60 cm) spaced 2.5 cm apart, and (iii) movable sample stage (anode) oscillating in the X–Y plane (20 mm amplitude) to ensure uniform treatment. Samples were placed in the discharge gap between the cathode and anode. Gas flow and exhaust systems were used to control the working atmosphere (Fig. 1). Transparent Wood Preparation Preparation of transparent wood composites involved three steps: (1) solvent-free dehydration, (2) low-temperature plasma treatment, and (3) polymer infiltration and curing. 1) Balsa wood samples underwent pre-freezing in freezer at -40 °C. Following freezing, samples were freeze-dried (lyophilized) under vacuum, with shelf temperatures carefully controlled to ensure complete sublimation of ice and removal of residual moisture. The resulting fully dried wood was immediately transferred to a desiccator for storage. 2) Plasma modification was conducted by placing dried samples in the ADRE setup, powered by a sinusoidal voltage (up to 50 kV peak-to-peak, 2 kHz). Air plasma at atmospheric pressure was applied at average power density of 0.9 J cm⁻¹ s⁻¹ for 900 s, generating a volumetric treatment of the scaffold (Fig. 2). More details concerning wood and wood products plasma treatments and their impact on wood properties can be found, for example, in scientific works (Hoppanová et al., 2020; Jablonsky et al., 2016; Maltsev, 2006; Mikula et al., 2009; Odrášková et al., 2008; Ráheľ et al., 2012; Šimor et al., 2002; Vizárová et al., 2021). 3) Infiltration of (2-hydroxyethyl)-methacrylate, dodecyl-methacrylate, (hexan-1,6-diyl)-diacrylate (60: 30: 10 wt%) was carried out without pre-polymerization. Activator (2,2´-azobis(2-methylpropionitrile, 0.2 wt%) was mixed with the acrylates and it was allowed to dissolve for 1 h. After full vacuum-infiltration the samples were sandwiched between two glass slides, packaged in aluminium foil, and the polymerization was performed in an oven at 90 °C for 2 h. In individual analyses, comparative study of three distinct sample types was conducted on raw wood (RW), transparent wood without plasma treatment (NPT-TW), and transparent wood with plasma treatment (PT-TW). This approach allowed for a focused examination of the effects of each processing step on the material's properties. Characterization Optical characterization FTIR spectra were collected on a Varian FT-IR 660 spectrometer equipped with a GladiATR diamond ATR accessory (PIKE Technologies, USA), operating from 4000–400 cm⁻¹ with 146 scans at 4 cm⁻¹ resolution. The resulting spectra were corrected for background air absorbance. The spectra were recorded using a Varian Resolutions Pro. Transmittance measurements were performed using a Cary 60–Agilent UV-Vis spectrophotometer (Agilent Technologies, Santa Clara, CA, USA) in the wavelength range of 380–780 nm. The analysis included three distinct sample types: pure acrylic resin, PT-TW, and NPT-TW. Prior to measurement, samples were prepared appropriately to ensure accurate light transmission analysis. Colour coordinates (L*, a*, b*) were determined using a NR200 colorimeter (Threenh Technology, China) equipped with an 8 mm aperture under D65 illumination. Thermogravimetric analysis Thermogravimetric analysis (TGA) was performed using a NETSCH STA 449 F5 Jupiter instrument. Measurements were conducted in both an inert atmosphere (N 2 ) and an air stream (80% N 2 + 20% O 2 ), with a flow rate of 100 ml.min -1 . Samples were heated at a constant rate of 10 °C.min -1 , and their weight was approximately 10 mg. Before measurement, all materials were dried at 103±2 °C to a constant weight. Determination of pseudo-components The mixchar R package was used to deconvolute TGA curves (N 2 atmosphere) into pseudo-components corresponding to hemicellulose, cellulose, and lignin, using the Fraser–Suzuki function. Initial values (Table 1) were adapted from Windecker et al. (Windecker et al., 2021), with adjusted peak positions based on DTG profiles of balsa (e.g., hemicellulose shifted to 300–318 °C in accordance with Carneiro-Junior et al. (Carneiro-Junior et al., 2019)). Deconvolution was performed over 120–700 °C. Table 1 Starting values for the nonlinear optimisation Parameter Component Height Skew Position Width start_vec Hemicellulose 0.003 -0.15 300 50 Cellulose 0.006 -0.15 350 30 Lignin 0.001 -0.15 410 200 lower_vec Hemicellulose 0 -0.33 0 50 Cellulose 0 -0.33 290 0 Lignin 0 -0.29 330 160 upper_vec Hemicellulose 2 0.25 330 100 Cellulose 2 0.25 380 50 Lignin 2 0.25 430 250 Results and discussion FTIR Analysis Basic hydrogen peroxide bleaching was applied to natural wood samples to assess alterations in their cell wall components, namely cellulose, hemicellulose, and lignin. The principal objective of this modification was lignin, which is paramount to the visual attributes and opacity of wood and wood-derived materials [46]. Infrared spectra, presented in Fig. 3 , illustrate the chemical structural transformations (e.g., bond scission or formation) occurring in both natural balsa wood and the post-bleaching samples. For a comprehensive comparison, the figure additionally provides FTIR spectra of delignified wood. The prominent band near 3310 cm⁻¹ is attributed to the –OH stretching vibrations of hydrogen bonds within wood components or absorbed water (Y. Li, Yang, et al., 2018 ; X. Wang et al., 2018 ). FTIR analysis revealed that the characteristic peaks for lignin and hemicellulose (1732, 1591, 1503, 1455, 1233 cm⁻¹) were either reduced or completely removed following alkaline hydrogen peroxide bleaching and delignification. Specifically, these wavenumbers correspond to: 1732 cm − 1 : C = O stretching of non-conjugated carbonyl (xylan), 1591 cm − 1 : C = C stretching of aromatic skeleton – symmetric (lignin), 1503 cm − 1 : C = C stretching of aromatic skeleton – asymmetric (lignin), 1455 cm − 1 : –CH 3 and -CH 2 asymmetrical bending (Lignin), 1233 cm − 1 : CO–OR stretching of acyl-oxygen bond (hemicellulose) and stretching of benzene-oxygen bond (lignin) (Liu et al., 2015 ; Park et al., 2022 ; Vay et al., 2021 ; S. Wang et al., 2020 ). The band at 1503 cm⁻¹ in the spectrum, characteristic of aromatic compounds (phenolic hydroxyl groups) and corresponding to aromatic skeletal vibrations of lignin, showed a slight decrease in intensity in the modified wood spectrum. This suggests that lignin was largely preserved, with only its chromophoric regions being affected. Conversely, the complete disappearance of the 1503 cm⁻¹ peak in the delignified wood spectrum confirms the removal of lignin from the wood structure (Y. Li, Fu, Rojas, et al., 2017 ). ATR-FTIR spectra of the original balsa wood (RW), plasma-treated transparent balsa wood (PT-TW), and no-plasma-treated transparent balsa wood (NPT-TW) (Fig. 4 ) reveal distinct differences in functional group absorptions. The RW spectrum exhibits a broad O–H stretching absorption in the 3200–3500 cm⁻¹ region, characteristic of cellulose, hemicellulose, and absorbed moisture. In both resin-infiltrated samples, this O–H band is markedly reduced, consistent with partial replacement by resin and/or hydrogen bonding between resin and wood hydroxyl groups. Concurrently, a pronounced carbonyl C = O stretching band emerges at 1715 cm⁻¹, along with intensified C–O–C and C–O stretching absorptions in the 1300–1000 cm⁻¹ range. These changes confirm the presence of the (meth)acrylate-based resin (i.e., HEMA, dodecyl-methacrylate, diacrylate) within the wood matrix, in agreement with typical ester functionality assignments in IR spectroscopy . Comparison of the resin-related carbonyl band reveals that the NPT-TW sample exhibits a higher intensity at 1715 cm⁻¹ relative to the PT-TW. This observation suggests that in the absence of plasma, the resin tends to remain at or near the wood surface, presumably due to poorer wettability or insufficient penetration. In contrast, plasma treatment appears to promote deeper resin infiltration, such that fewer free ester groups remain at the very surface; this results in a lower surface-sensitive C = O signal in ATR-FTIR. Similar behaviour has been reported in literature, where plasma pretreatment of wood surfaces enhanced adhesive uptake and promoted more homogeneous interfacial bonding, thereby reducing the amount of unbound resin detectable on the topmost layer (Mamiński et al., 2021 ; Tu et al., 2023 ). The carbohydrate fingerprint region (notably near 1386 cm⁻¹ and 1030 cm⁻¹) displays altered intensity and shape upon resin infiltration, owing to overlap with resin C–O vibrations and the physical occupation of cell lumina. In the plasma-treated sample, these wood-derived bands are further attenuated or shifted, indicating more intimate contact between resin and cell-wall components. This aligns with established findings that plasma treatment increases surface roughness and introduces polar functional groups — such as C–O and C = O — thereby enhancing wetting, chemical affinity, and potential bonding sites for resin molecules (Novák et al., 2018 ). FTIR results imply that plasma treatment favourably modifies the wood surface to promote stronger bonding with the acrylic resin. Specifically: 1. Improved Wettability and Penetration – Plasma exposure introduces oxygen-containing polar groups (e.g., –OH, –C = O, –C–O–) and physically etches the surface, increasing surface energy. These changes facilitate better resin wetting and capillary infiltration into the wood structure . 2. Reduced Resin Accumulation at the Surface – The attenuated surface ester (C = O) signal for the plasma-treated sample indicates less superficial resin pooling and more homogeneous resin distribution at the interface, supporting enhanced interlocking and potentially stronger adhesion. 3. Enhanced Interfacial Interaction – The masking of carbohydrate bands by resin in the plasma-treated sample suggests intimate interfacial mixing and greater coverage of wood polymers, which may lead to stronger hydrogen bonding or even limited covalent coupling during resin curing. These spectral observations, combined with literature precedent, strongly suggest that cold or atmospheric plasma pretreatment improves the compatibility and bonding performance of (meth)acrylate-based resin with wood substrates. UV-VIS spectroscopy To evaluate the optical properties of the modified balsa wood, transmittance measurements were conducted using a Cary 60–Agilent UV-VIS spectrophotometer. Figure 5 displays the transmittance spectra of three distinct samples: pure acrylic resin, plasma-treated transparent wood (PT-TW), and non-plasma treated transparent wood (NPT-TW), across the visible light spectrum ranging from 400 nm to 800 nm. Left: UV-VIS transmittance spectra of plasma-treated transparent wood (PT-TW), non-plasma-treated transparent wood (NPT-TW), and pure acrylic resin. Right: Photographs comparing visual transparency: a) PT-TW and b) NPT-TW. Plasma treatment leads to enhanced optical transmittance and clarity, approaching that of the pure resin. Plasma-Treated Transparent Wood (PT-TW) demonstrated a high transmittance of 91% at a wavelength of 550 nm, a significant increase from the 72% of non-plasma-treated samples. This high value is notably comparable to that of pure acrylic resin (95%), underscoring the effectiveness of the plasma approach in creating a highly transparent material. Although an 85% haze value indicates some light scattering still exists, the 11% reduction achieved through plasma treatment represents a significant improvement in the material’s optical clarity. Further optimization of the plasma parameters and infiltration process could lead to even greater clarity. These optical improvements are a direct result of the volumetric plasma modification. Conventional transparent wood often suffers from interface gaps and scattering centres due to the poor compatibility between cellulose and the infiltrating acrylic polymers. While FTIR analysis confirms that plasma treatment doesn't cause significant changes to the wood's bulk chemical composition, it activates the surface of the cellulose fibrils. This process can create new functional groups—such as carbonyl, carboxyl, and hydroxyl groups—which enhance the cellulose surface's compatibility with the polymer (Duan et al., 2024 ; Novak et al., 2019 ; Odrášková et al., 2008 ). This improved compatibility leads to more uniform polymer infiltration, minimizing voids and air pockets within the composite. Consequently, light scattering is reduced, resulting in higher transmittance and lower haze. The absence of harsh chemical treatments, which can damage the cellulose structure, further contributes to the material's optical quality. A summary of these and other findings from studies on transparent wood composites is provided in Table 2 , detailing the materials, methods, and optical properties used for their creation and characterization. Table 2 Overview of transparent wood composites based on balsa wood, listing the polymer matrix, preparation method, sample thickness, optical transmittance (at specified wavelengths) Wood Polymer Method Thickness [mm] Transmittance [%] (according to wavelength) Source Balsa limonene acrylate delignification 1.2 89 (Montanari et al., 2021 ) Balsa PMMA bleaching 1.5 83 (550 nm) (Y. Li, Fu, Rojas, et al., 2017 ) delignification 1.5 86 (550 nm) Balsa epoxy resin delignification 0.2 67 (750 nm) (Ding et al., 2022 ) Balsa melamine resin delignification 1.1 65 (Samanta et al., 2022 ) bleaching 1.2 68 Balsa TMMP, DBTDL, HDI delignification 2.0 (transv.) 89.92 (Tan et al., 2022 ) 2.0 (long) 70.88 Balsa epoxy resin delignification 1.0 71 (X. Chen et al., 2022 ) Balsa cellulose acetate delignification 1.0 83 (650 nm) (J. Zhang et al., 2023 ) Balsa epoxy resin bleaching 1.0 ≈ 90 (400–800 nm) (Xia et al., 2023 ) Balsa PMMA delignification 1.5 92 (Y. Li, Yang, et al., 2018 ) Balsa Acrylic resin bleaching 1.0 91 (550 nm) This study Colourimetry Both plasma-treated (PT-TW) and non-plasma-treated (NPT-TW) transparent wood samples exhibit substantial colour changes compared to raw wood (RW), confirming the effective removal of chromophoric lignin and extractives (Table 3 ). The drastic reduction in b* values from 17.422 in RW to 1.405 in PT-TW and 2.260 in NPT-TW, along with slight increases in L*, indicates a marked decrease in yellowness and increased lightness, consistent with delignification and bleaching processes reported in literature (Y. Li, Fu, Rojas, et al., 2017 ; Y. Li, Vasileva, et al., 2018 ). These optical modifications move the treated woods considerably closer to the standard white paper background used during measurement (L* = 91.256, b* = − 2.261), reflecting enhanced transparency, despite the samples retaining slight positive b* values due to residual hemicellulose or extractives, in agreement with previous observations (Y. Li, Fu, Yang, et al., 2017). Between the treated samples, PT-TW presents the lowest yellowness (b* = 1.405) and a lightness of L* = 81.926, yielding a more colour-neutral appearance, whereas the NPT-TW sample is slightly lighter (L* = 82.317) but shows marginally higher yellowness (b* = 2.260). Both treatments result in low redness (a* ≈2), demonstrating a major shift toward a neutral, transparent appearance relative to raw wood. The achievement of a more colour-neutral appearance, particularly in the PT-TW sample, is crucial for applications such as energy-efficient windows or advanced optical sensors, where accurate colour rendering is essential. Table 3 CIELAB colour coordinates (L , a*, b*) of raw wood (RW), plasma-treated transparent wood (PT-TW), and non-plasma-treated transparent wood (NPT-TW). Sample Lightness ( L* ) Redness ( a* ) Yellowness ( b* ) RW 79.774 3.159 17.422 PT-TW 81.926 1.951 1.405 NPT-TW 82.317 1.824 2.260 Standard white* 91.256 0.3222 -2.261 * White paper background used beneath samples during colour measurement. TGA Thermogravimetric (TG) and Derivative Thermogravimetric (DTG) curves for the raw and transparent wood samples are presented in Fig. 6 with summarized results in Table 4 . Mass loss generally occurred in multiple stages (Table 4 ). The initial stage, observed in both air and N 2 atmospheres at temperatures up to 110°C, is widely attributed to the evaporation of moisture from the samples (L. Li et al., 2019 ; Vahedi et al., 2022 ; L. Zhang et al., 2022 ). Due to the pre-drying of the materials before measurement, the observed mass losses in this region were minimal, likely stemming from moisture re-adsorption during sample preparation. In all cases, the raw wood exhibited higher moisture content than the transparent wood, which can be attributed to the enhanced hydrophobicity of the transparent wood (Bisht & Pandey, 2024 ; Xu et al., 2022 ; Zhou et al., 2022 ). In the N₂ atmosphere, the main stage of mass loss for all samples begins at approximately 180°C. This temperature for the onset of wood decomposition is also reported by Han et al. (Han et al., 2017 ). This initial phase is followed by a rapid decrease in mass caused by the thermal decomposition of the principal wood components. For raw wood, hemicelluloses are the first to decompose, followed by cellulose (Yang et al., 2007 ). Table 4 Summary of decomposition parameters (temperature ranges, maximum decomposition temperatures, and weight loss) for different wood samples analysed by TGA in N₂ and air atmospheres. Sample 1st region 2nd region 3rd region m 750°C Range [°C] T max1 [°C] Weight loss [%] Range [°C] T max1 [°C] Weight loss [%] Range [°C] T max2 [°C] Weight loss [%] N 2 RW < 105 67 0,7 185–381 347 72,4 - - - 17,2 PT-TW < 105 - 0,3 181–350 315 32,2 350–456 404 56,6 7,0 Air RW < 104 58 2,3 178–363 311 72,9 363–424 410 22,9 1,6 PT-TW < 102 62 0,5 153–383 324 86,7 383–451 435 10,6 1,7 These processes are clearly visible on the Derivative Thermogravimetric (DTG) curves. The decomposition of hemicelluloses corresponds to a shoulder at approximately 300°C, while cellulose decomposition corresponds to the main peak at about 350°C. The lignin peak is largely masked by these events due to its low intensity and the broad temperature range over which its decomposition occurs (Yang et al., 2007 ). In the case of PT-WT, the mass loss seen on the TG curve is more gradual and occurs over a wider temperature range. This results in a greater total mass loss for the PT-WT samples (approx. 90%) compared to the RW (approx. 73%). PT-WT have a significantly lower char yield (approximately 7%) compared to RW (17.2%). This is due to two factors: the removal of lignin, which is a primary source of char in wood pyrolysis, and the near-complete decomposition of the infiltrated acrylic resin at higher temperatures. The DTG peak near 450°C can be assigned to the decomposition of the resin. For the TW-B sample, this decomposition appears to occur in two distinct stages. The resin used is a multi-component system, and the thermal behaviour of its potential components has been described in the literature. For instance, the TGA of poly(2-hydroxyethyl methacrylate) (pHEMA) in a N 2 atmosphere reveals a single decomposition stage between 195°C and 400°C, which leaves approximately 5–6% of the original mass as a carbonaceous residue (Demirelli et al., 2001 ). Another component, dodecyl methacrylate homopolymer, was reported to begin decomposing in air at 150°C, with a total mass loss of 75% by 400°C (Ghosh et al., 2017 ). Finally, poly(1,6-hexanediol diacrylate) (pHDDA) degrades in a single step between approximately 300°C and 500°C. Its degradation proceeds via random chain scission and chain-end scission mechanisms, also resulting in a carbon residue (Goswami et al., 2010 ). When measured in air, two significant changes occur. First, the transparent wood begins to decompose at a temperature approximately 25°C lower, indicating that the resin's decomposition is accelerated by the presence of oxygen. Second, heterogeneous oxidation of the charred residue is visible between 400 and 450°C. The TGA data reveal that the individual components of the pHEMA, dodecyl methacrylate homopolymer, and poly(1,6-hexanediol diacrylate) (pHDDA) have distinct thermal degradation profiles. This is crucial because it indicates that the transparent wood composite's overall thermal stability is a combination of these profiles. The degradation of the composite won't occur at a single temperature but rather across a broad range, influenced by the degradation of each component. The composite will likely start to degrade at the lowest temperature of its components, which is the dodecyl methacrylate homopolymer at around 150°C in air. Furthermore, the TGA results highlight the critical role of the atmosphere (air vs. nitrogen) in the composite's degradation. The observed 25°C drop in the decomposition temperature in air compared to N 2 signifies that oxidative degradation is a major factor. The presence of oxygen catalyses the breakdown of the resin, making the transparent wood composite less thermally stable in an oxygen-rich environment than in an inert one. The final mass loss from the heterogeneous oxidation of the charred residue at 400–450°C further confirms the composite's vulnerability to oxidative thermal degradation. The material exhibits a thermal profile that aligns with the requirements of various construction and electronics applications, where operational temperatures are not anticipated to exceed its degradation threshold. This characteristic is a vital consideration for its real-world viability, as exposure to elevated temperatures would significantly increase its susceptibility to degradation. Conclusion This study successfully demonstrated the efficacy of Atmospheric Discharge with Runaway Electrons (ADRE) plasma for modifying the entire volume of bleached and dehydrated wood samples. The unique characteristics of ADRE plasma, particularly its ability to generate high-energy electrons (several tens of keV) at atmospheric pressure, significantly distinguish it from conventional plasma systems. This enables an unparalleled level of material modification and surface property enhancement, such as improved wetting, comparable to low-pressure, near-vacuum discharges, but crucially, without their associated complexity and cost. The developed plasma-based approach markedly enhances the material's optical properties, achieving a high transmittance of up to 91% and notably reducing haze compared to non-plasma-treated composites (72%). This performance represents a substantial improvement over transparent balsa wood prepared with traditional chemical methods. A key benefit of this innovative method is the complete elimination of harsh organic solvents and chemicals typically used for wood dehydration and interface modification. By bypassing these complex, hazardous, and time-consuming chemical treatments, the proposed method significantly reduces production time, cost, and the overall environmental burden of traditional fabrication. By addressing critical challenges in safety, cost, and environmental impact, this work marks a significant step towards making transparent wood a practical, high-performance, and sustainable material. This streamlined, solvent-free plasma treatment offers a scalable and more environmentally friendly pathway for creating advanced optical bio-composites for energy-efficient smart buildings and other next-generation technologies. Further research will focus on optimizing plasma parameters for a broader range of wood species and thicknesses, exploring compatibility with emerging sustainable methods for transparent wood fabrication (e.g., enzymatic delignification, methods using DES), and investigating the scalability of the fabrication process for industrial applications. Additionally, we will investigate bio-based polymer systems that could offer even better performance or specific functionalities, and a detailed assessment of the long-term mechanical and environmental stability of the plasma-treated transparent wood will be crucial for its widespread adoption in various applications. Declarations Author Contribution Conceptualisation, I.W. and T.Š.; methodology, I.W., A.H., R.T.; software, P.R., T.Š., L.B.,; validation, I.W., T.Š. and P.R.;formal analysis, I.W., T.Š., L.B.;investigation, I.W., P.R.;resources, I.W. and J.M., A.H.;data curation, I.W., T.Š., J.M. and P.R.;writing—original draft preparation, I.W. and T.Š.;writing—review and editing, I.W. and T.Š.; visualisation T.Š. and R.T.;funding acquisition, I.W.;All authors have read and agreed to the published version of the manuscript. Data Availability Data is provided within the manuscript or supplementary information files. 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12:38:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7426252/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7426252/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10570-026-07013-3","type":"published","date":"2026-03-23T16:08:28+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":93754168,"identity":"fe4dd5b0-f3f1-4b90-8b71-45d4e643658a","added_by":"auto","created_at":"2025-10-17 08:24:26","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":56755,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of the ADRE plasma apparatus for atmospheric pressure treatment.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/0d99282919d3eb5960eefcf7.png"},{"id":93754167,"identity":"0e70af24-8234-40bd-8da4-5ae974e64ff4","added_by":"auto","created_at":"2025-10-17 08:24:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":195637,"visible":true,"origin":"","legend":"\u003cp\u003ePlasma treatment of modified wood scaffolds in the ADRA plasma apparatus\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/b2f859e09315759d8623b7dd.png"},{"id":93754568,"identity":"351e2f46-9479-48dc-a927-7c3fafd77f6f","added_by":"auto","created_at":"2025-10-17 08:32:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":106276,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectroscopic analysis revealing the impact of basic hydrogen peroxide bleaching on Balsa wood's chemical structure. Presented are spectra for the raw balsa wood (RW), the bleached (modified) sample, and a reference delignified sample, allowing for comparison of lignin and polysaccharide modifications\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/ed55cb605c6e6c081047e6e4.png"},{"id":93754195,"identity":"c7e67662-d094-4e66-99bd-179f63280e5b","added_by":"auto","created_at":"2025-10-17 08:24:29","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":134743,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectroscopic analysis revealing the impact of plasma treatment on Balsa wood's chemical structure. Presented are spectra for the raw balsa wood (RW), the plasma-treated transparent wood (PT-TW) sample, and a reference non-plasma treated transparent wood (NPT-TW) sample, allowing for a comparison of chemical modifications.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/5b206ea9aec2ce232443531f.png"},{"id":93754199,"identity":"24bc160a-b583-4ce5-8b5f-9f3136e99b1a","added_by":"auto","created_at":"2025-10-17 08:24:31","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":220779,"visible":true,"origin":"","legend":"\u003cp\u003eOptical evaluation of plasma-treated versus untreated transparent wood samples.\u003cbr\u003e\nLeft: UV-VIS transmittance spectra of plasma-treated transparent wood (PT-TW), non-plasma-treated transparent wood (NPT-TW), and pure acrylic resin. Right: Photographs comparing visual transparency: a) PT-TW and b) NPT-TW. Plasma treatment leads to enhanced optical transmittance and clarity, approaching that of the pure resin.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/04cb1873abddac788f4f9bd9.png"},{"id":93754198,"identity":"ae7e6830-14ec-4aa7-8b1e-fece869c53c1","added_by":"auto","created_at":"2025-10-17 08:24:30","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":92026,"visible":true,"origin":"","legend":"\u003cp\u003eThermogravimetric (TG) and derivative thermogravimetric (DTG) curves of raw wood (RW) and plasma-treated transparent wood (PT-TW) under (A) nitrogen and (B) air atmosphere.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/359fae3d3d167e770a9be361.png"},{"id":106092930,"identity":"bb754507-8684-4e29-9ce6-7bc178f16c20","added_by":"auto","created_at":"2026-04-03 11:30:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1809602,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7426252/v1/0dbfe56c-bc82-4c8c-9b28-f469b3674edd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Enhancing optical properties of transparent wood by plasma modification","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAccording to a 2022 IPCC report, Earth is predicted to reach 1.5\u0026deg;C of warming within the next two decades, necessitating drastic reductions in carbon emissions to avert an environmental catastrophe (P\u0026ouml;rtner et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). A critical focus must be placed on sustainable growth and reducing reliance on fossil fuels, which are the source of most of the 36\u0026nbsp;billion metric tons of CO\u003csup\u003e2\u003c/sup\u003e emitted globally each year. The construction industry is a significant contributor, accounting for 37% of all CO\u003csup\u003e2\u003c/sup\u003e emissions in 2020 through its activities and materials (USGCRP, 2017). To mitigate this impact, it is essential to design high-performance, multipurpose building materials. While glass is widely used for windows, its brittleness and energy-intensive manufacturing are considerable drawbacks. In contrast, wood offers superior mechanical strength, natural abundance, and renewability (C. Chen et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). This has driven the development of transparent wood, a transformative material positioned as a sustainable alternative with advanced applications such as multi-functional windows (Mi et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Mishra et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Qiu et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), integrated solar cells (Y. Li et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Zhu, Li, et al., \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), thermal energy storage systems (Y. Li et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Montanari et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), and even load-bearing structural elements in modern architecture (Fu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Karľa, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Katunsk\u0026yacute; et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWood is a porous and fibrous composite of cellulose, hemicellulose, and lignin (Jin et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Its natural opacity is primarily due to lignin, whose chromophoric compounds\u0026mdash;such as carbonyl groups, biphenyls, and ring-conjugated double bonds\u0026mdash;absorb light across the visible spectrum (Sadeghifar \u0026amp; Ragauskas, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). To achieve transparency, a two-step process is conventionally employed. First, the lignin is removed or bleached from the wood scaffold through aggressive chemical delignification using agents like sodium chlorite (NaClO₂) (Zhu, Song, et al., \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), sodium hydroxide (Y. Li, Fu, Rojas, et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), or hydrogen peroxide (H₂O₂) (H. Li et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Second, the remaining porous cellulose scaffold is infiltrated with a polymer that has a refractive index matching that of cellulose (n\u0026thinsp;\u0026asymp;\u0026thinsp;1.5), such as PMMA (Y. Li et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), epoxy (Zhu et al., \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), or PVA (Tang et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), to create a transparent composite.\u003c/p\u003e\u003cp\u003eHowever, despite its promise, the conventional fabrication of transparent wood presents significant environmental, economic, and performance challenges that impede its widespread adoption. The delignification processes rely on chemicals that are often toxic and environmentally harmful, creating substantial issues for their safe disposal and potential reuse (Simelane et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). These intricate and harsh chemical treatments also contribute to higher production costs compared to traditional transparent materials, hindering scalability (Hai et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Furthermore, the delignification process exposes hydrophilic hydroxyl groups on the cellulose scaffold, leading to poor compatibility with the hydrophobic polymers used for infiltration. This mismatch can cause interface gaps and compromise the composite's optical quality and long-term durability (Y. Li, Yang, et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Collectively, these burdens undermine the inherent sustainability of using wood as a green building material.\u003c/p\u003e\u003cp\u003ePlasma treatment is a versatile and efficient (surface-modification) technique that can be used to enhance the properties of cellulose-based scaffolds. The process involves bombarding the material with an ionized gas, which breaks chemical bonds and creates highly reactive sites on the cellulose surface without altering its bulk properties (Nisoa \u0026amp; Wanichapichart, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Rifathin et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This activation can be used to introduce new functional groups, such as hydroxyl (-OH), carbonyl (C\u0026thinsp;=\u0026thinsp;O), and carboxyl (-COOH) groups, which increase the surface energy and wettability of the cellulose (Alanis et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Chiper \u0026amp; Borcia, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). This modification is crucial for improving the scaffold's performance and compatibility with other materials.\u003c/p\u003e\u003cp\u003eThe current study introduces a novel and effective method to fabricate transparent wood (Balsa wood - \u003cem\u003eOchroma pyramidale L.\u003c/em\u003e) by employing a volumetric plasma modification. Whereas conventional plasma treatments are limited to surface modification, here the principle is extended to treat the entire scaffold. This strategy circumvents the need for harsh chemical reagents and solvents traditionally used for delignification, thereby addressing key challenges in cost, environmental safety, and scalability. By demonstrating that plasma treatment can effectively improve transparency and interfacial compatibility, this work provides a (promising new pathway) toward the practical realization of high-performance, sustainable transparent wood materials for smart building and advanced technological applications.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003ch2\u003eMaterials and chemicals\u003c/h2\u003e\n\u003cp\u003eLongitudinally cut balsa wood (\u003cem\u003eOchroma pyramidale\u003c/em\u003e \u003cem\u003eL.\u003c/em\u003e), with density of 0.15\u0026ndash;0.17 g.cm\u003csup\u003e\u0026minus;3\u003c/sup\u003e, was procured from JAF Holz Slovakia Ltd. Samples measuring 50 \u0026times; 50 \u0026times; 1 mm were prepared for various tests. FTIR analysis, colorimetry, UV-VIS analysis, and thermal analysis were performed on a 1 mm thick samples (other dimensions were determined by the analysis itself and instrument requirements). Sodium silicate (Na₂SiO₃, 36/38 \u0026deg;B\u0026eacute;), sodium hydroxide (NaOH, p.a. \u0026lt;99%), magnesium sulphate (MgSO\u003csub\u003e4\u003c/sub\u003e, p.a. 98%), ethylenediaminetetraacetic acid (EDTA, p.a., \u0026lt;99%) and hydrogen peroxide (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e,p.a. 35%) were purchased from CentralChem Ltd. \u0026nbsp;Deionised water was prepared directly in the laboratory. \u0026nbsp;(2-hydroxyethyl)-methacrylate (97%), (hexane-1,6-diyl)-diacrylate (80%) and 2,2-Azobis(2-methylpropionitrile) were purchased from Sigma-Aldrich. Dodecyl-methacrylate (97%) was purchased from Avantor, Inc. All the chemicals were used as received without further purification.\u003c/p\u003e\n\u003ch2\u003eLignin Modification\u003c/h2\u003e\n\u003cp\u003eThe lignin modification procedure was originally proposed by Li et al. (Y. Li, Fu, Rojas, et al., 2017). Balsa wood samples were submerged into a lignin modifying solution at 70 \u0026deg;C. The solution was prepared by mixing chemicals in the following order: deionized water, sodium silicate (3 wt%), sodium hydroxide solution (3 wt%), magnesium sulphate (0.1 wt%), DTPA (0.1 wt%), and then H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e (4.0 wt%). Subsequently, additional 35% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e solution was gradually supplemented over the course of a few hours until the samples became completely white. This continuous addition was necessary to compensate for H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e decomposition during the reaction. The samples were then replaced to a deionized water bath for 24 h to let the residual chemical leach out and diffuse.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003ePlasma treatment\u003c/h2\u003e\n\u003cp\u003eTo modify the entire volume of the bleached and dehydrated wood samples plasma treatment was used. The Atmospheric Discharge with Runaway Electrons (ADRE) plasma was used. It combines the advantages of low-temperature plasma at low pressure and plasma at atmospheric pressure. One of the main features of ADRE plasma is the creation of a large number of fast electrons in the region of a given power. These electrons acquire energy of up to several tens of kiloelectronvolts (keV), while the average energy of electrons in other discharges reaches the order of several electronvolts (eV). In terms of the effectiveness of the impact on wetting and other properties of materials, ADRE plasma significantly surpasses all existing atmospheric discharges and is close to discharges generated at low pressure almost at the vacuum level. This allows processing the material at high speed, and the possibility of including ADRE plasma equipment in a continuous technological process.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo modify the entire scaffold of the bleached and dehydrated wood samples, plasma treatment was applied using Atmospheric Discharge with Runaway Electrons (ADRE) plasma. This discharge produces a high number of fast electrons (reaching tens of keV), surpassing conventional atmospheric plasmas in effectiveness for surface activation. The plasma apparatus comprised: (i) a (computer-controlled) high-voltage power supply (max. 50 kV; Kamea s.r.o., Pie\u0026scaron;ťany, Slovakia), (ii) a working chamber equipped with two parallel planar electrodes (20 \u0026times; 60 cm) spaced 2.5 cm apart, and (iii) movable sample stage (anode) oscillating in the X\u0026ndash;Y plane (20 mm amplitude) to ensure uniform treatment. Samples were placed in the discharge gap between the cathode and anode. Gas flow and exhaust systems were used to control the working atmosphere (Fig. 1).\u003c/p\u003e\n\u003ch2\u003eTransparent Wood Preparation\u003c/h2\u003e\n\u003cp\u003ePreparation of transparent wood composites involved three steps: (1) solvent-free dehydration, (2) low-temperature plasma treatment, and (3) polymer infiltration and curing.\u003c/p\u003e\n\u003cp\u003e1)\u0026nbsp; \u0026nbsp;Balsa wood samples underwent pre-freezing in freezer at -40 \u0026deg;C. Following freezing, samples were freeze-dried (lyophilized) under vacuum, with shelf temperatures carefully controlled to ensure complete sublimation of ice and removal of residual moisture. \u0026nbsp;The resulting fully dried wood was immediately transferred to a desiccator for storage.\u003c/p\u003e\n\u003cp\u003e2)\u0026nbsp; \u0026nbsp;Plasma modification was conducted by placing dried samples in the ADRE setup, powered by a sinusoidal voltage (up to 50 kV peak-to-peak, 2 kHz). Air plasma at atmospheric pressure was applied at average power density of 0.9 J cm⁻\u0026sup1; s⁻\u0026sup1; for 900 s, generating a volumetric treatment of the scaffold (Fig. 2).\u003c/p\u003e\n\u003cp\u003eMore details concerning wood and wood products plasma treatments and their impact on wood properties can be found, for example, in scientific works (Hoppanov\u0026aacute; et al., 2020; Jablonsky et al., 2016; Maltsev, 2006; Mikula et al., 2009; Odr\u0026aacute;\u0026scaron;kov\u0026aacute; et al., 2008; R\u0026aacute;heľ et al., 2012; \u0026Scaron;imor et al., 2002; Viz\u0026aacute;rov\u0026aacute; et al., 2021).\u003c/p\u003e\n\u003cp\u003e3) \u0026nbsp; Infiltration of (2-hydroxyethyl)-methacrylate, dodecyl-methacrylate, (hexan-1,6-diyl)-diacrylate (60: 30: 10 wt%) was carried out without pre-polymerization. Activator (2,2\u0026acute;-azobis(2-methylpropionitrile, 0.2 wt%) was mixed with the acrylates and it was allowed to dissolve for 1 h. After full vacuum-infiltration the samples were sandwiched between two glass slides, packaged in aluminium foil, and the polymerization was performed in an oven at 90 \u0026deg;C for 2 h.\u003c/p\u003e\n\u003cp\u003eIn individual analyses, comparative study of three distinct sample types was conducted on raw wood (RW), transparent wood without plasma treatment (NPT-TW), and transparent wood with plasma treatment (PT-TW). This approach allowed for a focused examination of the effects of each processing step on the material\u0026apos;s properties.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eCharacterization\u003c/h2\u003e\n\u003ch3\u003eOptical characterization\u003c/h3\u003e\n\u003cp\u003eFTIR spectra were collected on a Varian FT-IR 660 spectrometer equipped with a GladiATR diamond ATR accessory (PIKE Technologies, USA), operating from 4000\u0026ndash;400 cm⁻\u0026sup1; with 146 scans at 4 cm⁻\u0026sup1; resolution. The resulting spectra were corrected for background air absorbance. The spectra were recorded using a Varian Resolutions Pro.\u003c/p\u003e\n\u003cp\u003eTransmittance measurements were performed using a Cary 60\u0026ndash;Agilent UV-Vis spectrophotometer (Agilent Technologies, Santa Clara, CA, USA) in the wavelength range of 380\u0026ndash;780 nm. The analysis included three distinct sample types: pure acrylic resin, PT-TW, and NPT-TW. Prior to measurement, samples were prepared appropriately to ensure accurate light transmission analysis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eColour coordinates (L*, a*, b*) were determined using a NR200 colorimeter (Threenh Technology, China) equipped with an 8 mm aperture under D65 illumination.\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003eThermogravimetric analysis\u003c/h3\u003e\n\u003cp\u003eThermogravimetric analysis (TGA) was performed using a NETSCH STA 449 F5 Jupiter instrument. Measurements were conducted in both an inert atmosphere (N\u003csub\u003e2\u003c/sub\u003e) and an air stream (80% N\u003csub\u003e2\u003c/sub\u003e + 20% O\u003csub\u003e2\u003c/sub\u003e), with a flow rate of 100 ml.min\u003csup\u003e-1\u003c/sup\u003e. Samples were heated at a constant rate of 10 \u0026deg;C.min\u003csup\u003e-1\u003c/sup\u003e, and their weight was approximately 10 mg. Before measurement, all materials were dried at 103\u0026plusmn;2 \u0026deg;C to a constant weight.\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003eDetermination of pseudo-components\u003c/h3\u003e\n\u003cp\u003eThe \u003cem\u003emixchar\u003c/em\u003e R package was used to deconvolute TGA curves (N\u003csub\u003e2\u003c/sub\u003e atmosphere) into pseudo-components corresponding to hemicellulose, cellulose, and lignin, using the Fraser\u0026ndash;Suzuki function. Initial values (Table 1) were adapted from Windecker et al. (Windecker et al., 2021), with adjusted peak positions based on DTG profiles of balsa (e.g., hemicellulose shifted to 300\u0026ndash;318 \u0026deg;C in accordance with Carneiro-Junior et al. (Carneiro-Junior et al., 2019)). Deconvolution was performed over 120\u0026ndash;700 \u0026deg;C.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e Starting values for the nonlinear optimisation\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eComponent\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHeight\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSkew\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosition\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWidth\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003estart_vec\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eHemicellulose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e-0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e300\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eCellulose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.006\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e-0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e350\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eLignin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e-0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e410\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e200\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003elower_vec\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eHemicellulose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e-0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eCellulose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e-0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eLignin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e-0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e330\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e160\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eupper_vec\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eHemicellulose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e330\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eCellulose\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e380\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eLignin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e430\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e250\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eFTIR Analysis\u003c/h2\u003e\u003cp\u003eBasic hydrogen peroxide bleaching was applied to natural wood samples to assess alterations in their cell wall components, namely cellulose, hemicellulose, and lignin. The principal objective of this modification was lignin, which is paramount to the visual attributes and opacity of wood and wood-derived materials [46]. Infrared spectra, presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, illustrate the chemical structural transformations (e.g., bond scission or formation) occurring in both natural balsa wood and the post-bleaching samples. For a comprehensive comparison, the figure additionally provides FTIR spectra of delignified wood.\u003c/p\u003e\u003cp\u003eThe prominent band near 3310 cm⁻\u0026sup1; is attributed to the \u0026ndash;OH stretching vibrations of hydrogen bonds within wood components or absorbed water (Y. Li, Yang, et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; X. Wang et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). FTIR analysis revealed that the characteristic peaks for lignin and hemicellulose (1732, 1591, 1503, 1455, 1233 cm⁻\u0026sup1;) were either reduced or completely removed following alkaline hydrogen peroxide bleaching and delignification. Specifically, these wavenumbers correspond to:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e1732 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e: C\u0026thinsp;=\u0026thinsp;O stretching of non-conjugated carbonyl (xylan),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e1591 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e: C\u0026thinsp;=\u0026thinsp;C stretching of aromatic skeleton \u0026ndash; symmetric (lignin),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e1503 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e: C\u0026thinsp;=\u0026thinsp;C stretching of aromatic skeleton \u0026ndash; asymmetric (lignin),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e1455 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e: \u0026ndash;CH\u003csub\u003e3\u003c/sub\u003e and -CH\u003csub\u003e2\u003c/sub\u003e asymmetrical bending (Lignin),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e1233 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e: CO\u0026ndash;OR stretching of acyl-oxygen bond (hemicellulose) and stretching of benzene-oxygen bond (lignin) (Liu et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Park et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Vay et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; S. Wang et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe band at 1503 cm⁻\u0026sup1; in the spectrum, characteristic of aromatic compounds (phenolic hydroxyl groups) and corresponding to aromatic skeletal vibrations of lignin, showed a slight decrease in intensity in the modified wood spectrum. This suggests that lignin was largely preserved, with only its chromophoric regions being affected. Conversely, the complete disappearance of the 1503 cm⁻\u0026sup1; peak in the delignified wood spectrum confirms the removal of lignin from the wood structure (Y. Li, Fu, Rojas, et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eATR-FTIR spectra of the original balsa wood (RW), plasma-treated transparent balsa wood (PT-TW), and no-plasma-treated transparent balsa wood (NPT-TW) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) reveal distinct differences in functional group absorptions. The RW spectrum exhibits a broad O\u0026ndash;H stretching absorption in the 3200\u0026ndash;3500 cm⁻\u0026sup1; region, characteristic of cellulose, hemicellulose, and absorbed moisture. In both resin-infiltrated samples, this O\u0026ndash;H band is markedly reduced, consistent with partial replacement by resin and/or hydrogen bonding between resin and wood hydroxyl groups. Concurrently, a pronounced carbonyl C\u0026thinsp;=\u0026thinsp;O stretching band emerges at 1715 cm⁻\u0026sup1;, along with intensified C\u0026ndash;O\u0026ndash;C and C\u0026ndash;O stretching absorptions in the 1300\u0026ndash;1000 cm⁻\u0026sup1; range. These changes confirm the presence of the (meth)acrylate-based resin (i.e., HEMA, dodecyl-methacrylate, diacrylate) within the wood matrix, in agreement with typical ester functionality assignments in IR spectroscopy .\u003c/p\u003e\u003cp\u003eComparison of the resin-related carbonyl band reveals that the NPT-TW sample exhibits a higher intensity at 1715 cm⁻\u0026sup1; relative to the PT-TW. This observation suggests that in the absence of plasma, the resin tends to remain at or near the wood surface, presumably due to poorer wettability or insufficient penetration. In contrast, plasma treatment appears to promote deeper resin infiltration, such that fewer free ester groups remain at the very surface; this results in a lower surface-sensitive C\u0026thinsp;=\u0026thinsp;O signal in ATR-FTIR. Similar behaviour has been reported in literature, where plasma pretreatment of wood surfaces enhanced adhesive uptake and promoted more homogeneous interfacial bonding, thereby reducing the amount of unbound resin detectable on the topmost layer (Mamiński et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Tu et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe carbohydrate fingerprint region (notably near 1386 cm⁻\u0026sup1; and 1030 cm⁻\u0026sup1;) displays altered intensity and shape upon resin infiltration, owing to overlap with resin C\u0026ndash;O vibrations and the physical occupation of cell lumina. In the plasma-treated sample, these wood-derived bands are further attenuated or shifted, indicating more intimate contact between resin and cell-wall components. This aligns with established findings that plasma treatment increases surface roughness and introduces polar functional groups \u0026mdash; such as C\u0026ndash;O and C\u0026thinsp;=\u0026thinsp;O \u0026mdash; thereby enhancing wetting, chemical affinity, and potential bonding sites for resin molecules (Nov\u0026aacute;k et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFTIR results imply that plasma treatment favourably modifies the wood surface to promote stronger bonding with the acrylic resin. Specifically:\u003c/p\u003e\u003cp\u003e1. Improved Wettability and Penetration \u0026ndash; Plasma exposure introduces oxygen-containing polar groups (e.g., \u0026ndash;OH, \u0026ndash;C\u0026thinsp;=\u0026thinsp;O, \u0026ndash;C\u0026ndash;O\u0026ndash;) and physically etches the surface, increasing surface energy. These changes facilitate better resin wetting and capillary infiltration into the wood structure .\u003c/p\u003e\u003cp\u003e2. Reduced Resin Accumulation at the Surface \u0026ndash; The attenuated surface ester (C\u0026thinsp;=\u0026thinsp;O) signal for the plasma-treated sample indicates less superficial resin pooling and more homogeneous resin distribution at the interface, supporting enhanced interlocking and potentially stronger adhesion.\u003c/p\u003e\u003cp\u003e3. Enhanced Interfacial Interaction \u0026ndash; The masking of carbohydrate bands by resin in the plasma-treated sample suggests intimate interfacial mixing and greater coverage of wood polymers, which may lead to stronger hydrogen bonding or even limited covalent coupling during resin curing.\u003c/p\u003e\u003cp\u003eThese spectral observations, combined with literature precedent, strongly suggest that cold or atmospheric plasma pretreatment improves the compatibility and bonding performance of (meth)acrylate-based resin with wood substrates.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eUV-VIS spectroscopy\u003c/h2\u003e\u003cp\u003eTo evaluate the optical properties of the modified balsa wood, transmittance measurements were conducted using a Cary 60\u0026ndash;Agilent UV-VIS spectrophotometer. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e displays the transmittance spectra of three distinct samples: pure acrylic resin, plasma-treated transparent wood (PT-TW), and non-plasma treated transparent wood (NPT-TW), across the visible light spectrum ranging from 400 nm to 800 nm.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eLeft: UV-VIS transmittance spectra of plasma-treated transparent wood (PT-TW), non-plasma-treated transparent wood (NPT-TW), and pure acrylic resin. Right: Photographs comparing visual transparency: a) PT-TW and b) NPT-TW. Plasma treatment leads to enhanced optical transmittance and clarity, approaching that of the pure resin.\u003c/p\u003e\u003cp\u003ePlasma-Treated Transparent Wood (PT-TW) demonstrated a high transmittance of 91% at a wavelength of 550 nm, a significant increase from the 72% of non-plasma-treated samples. This high value is notably comparable to that of pure acrylic resin (95%), underscoring the effectiveness of the plasma approach in creating a highly transparent material. Although an 85% haze value indicates some light scattering still exists, the 11% reduction achieved through plasma treatment represents a significant improvement in the material\u0026rsquo;s optical clarity. Further optimization of the plasma parameters and infiltration process could lead to even greater clarity.\u003c/p\u003e\u003cp\u003eThese optical improvements are a direct result of the volumetric plasma modification. Conventional transparent wood often suffers from interface gaps and scattering centres due to the poor compatibility between cellulose and the infiltrating acrylic polymers. While FTIR analysis confirms that plasma treatment doesn't cause significant changes to the wood's bulk chemical composition, it activates the surface of the cellulose fibrils. This process can create new functional groups\u0026mdash;such as carbonyl, carboxyl, and hydroxyl groups\u0026mdash;which enhance the cellulose surface's compatibility with the polymer (Duan et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Novak et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Odr\u0026aacute;škov\u0026aacute; et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). This improved compatibility leads to more uniform polymer infiltration, minimizing voids and air pockets within the composite. Consequently, light scattering is reduced, resulting in higher transmittance and lower haze. The absence of harsh chemical treatments, which can damage the cellulose structure, further contributes to the material's optical quality. A summary of these and other findings from studies on transparent wood composites is provided in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, detailing the materials, methods, and optical properties used for their creation and characterization.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOverview of transparent wood composites based on balsa wood, listing the polymer matrix, preparation method, sample thickness, optical transmittance (at specified wavelengths)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWood\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePolymer\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMethod\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThickness [mm]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eTransmittance [%] (according to wavelength)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSource\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003elimonene acrylate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e(Montanari et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ePMMA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ebleaching\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e83 (550 nm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(Y. Li, Fu, Rojas, et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e86 (550 nm)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eepoxy resin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e67 (750 nm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e(Ding et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003emelamine resin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(Samanta et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ebleaching\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e68\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTMMP, DBTDL, HDI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.0 (transv.)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e89.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(Tan et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.0 (long)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e70.88\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eepoxy resin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e(X. Chen et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ecellulose acetate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e83 (650 nm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e(J. Zhang et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eepoxy resin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ebleaching\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026asymp;\u0026thinsp;90 (400\u0026ndash;800 nm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e(Xia et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePMMA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003edelignification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e(Y. Li, Yang, et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalsa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAcrylic resin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ebleaching\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e91 (550 nm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eThis study\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eColourimetry\u003c/h2\u003e\u003cp\u003eBoth plasma-treated (PT-TW) and non-plasma-treated (NPT-TW) transparent wood samples exhibit substantial colour changes compared to raw wood (RW), confirming the effective removal of chromophoric lignin and extractives (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The drastic reduction in b* values from 17.422 in RW to 1.405 in PT-TW and 2.260 in NPT-TW, along with slight increases in L*, indicates a marked decrease in yellowness and increased lightness, consistent with delignification and bleaching processes reported in literature (Y. Li, Fu, Rojas, et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Y. Li, Vasileva, et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). These optical modifications move the treated woods considerably closer to the standard white paper background used during measurement (L* = 91.256, b* = \u0026minus;\u0026thinsp;2.261), reflecting enhanced transparency, despite the samples retaining slight positive b* values due to residual hemicellulose or extractives, in agreement with previous observations (Y. Li, Fu, Yang, et al., 2017). Between the treated samples, PT-TW presents the lowest yellowness (b* = 1.405) and a lightness of L* = 81.926, yielding a more colour-neutral appearance, whereas the NPT-TW sample is slightly lighter (L* = 82.317) but shows marginally higher yellowness (b* = 2.260). Both treatments result in low redness (a* \u0026asymp;2), demonstrating a major shift toward a neutral, transparent appearance relative to raw wood. The achievement of a more colour-neutral appearance, particularly in the PT-TW sample, is crucial for applications such as energy-efficient windows or advanced optical sensors, where accurate colour rendering is essential.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e\u003cem\u003eCIELAB colour coordinates (L\u003c/em\u003e, a*, b*) of raw wood (RW), plasma-treated transparent wood (PT-TW), and non-plasma-treated transparent wood (NPT-TW).\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLightness (\u003cem\u003eL*\u003c/em\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRedness (\u003cem\u003ea*\u003c/em\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eYellowness (\u003cem\u003eb*\u003c/em\u003e)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e79.774\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.159\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e17.422\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePT-TW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e81.926\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.951\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.405\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNPT-TW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e82.317\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.824\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.260\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eStandard white*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e91.256\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.3222\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-2.261\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e\u003cp\u003e* White paper background used beneath samples during colour measurement.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eTGA\u003c/h2\u003e\u003cp\u003eThermogravimetric (TG) and Derivative Thermogravimetric (DTG) curves for the raw and transparent wood samples are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e with summarized results in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eMass loss generally occurred in multiple stages (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The initial stage, observed in both air and N\u003csub\u003e2\u003c/sub\u003e atmospheres at temperatures up to 110\u0026deg;C, is widely attributed to the evaporation of moisture from the samples (L. Li et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Vahedi et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; L. Zhang et al., \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Due to the pre-drying of the materials before measurement, the observed mass losses in this region were minimal, likely stemming from moisture re-adsorption during sample preparation. In all cases, the raw wood exhibited higher moisture content than the transparent wood, which can be attributed to the enhanced hydrophobicity of the transparent wood (Bisht \u0026amp; Pandey, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Xu et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Zhou et al., \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn the N₂ atmosphere, the main stage of mass loss for all samples begins at approximately 180\u0026deg;C. This temperature for the onset of wood decomposition is also reported by Han et al. (Han et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). This initial phase is followed by a rapid decrease in mass caused by the thermal decomposition of the principal wood components. For raw wood, hemicelluloses are the first to decompose, followed by cellulose (Yang et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of decomposition parameters (temperature ranges, maximum decomposition temperatures, and weight loss) for different wood samples analysed by TGA in N₂ and air atmospheres.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e1st region\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003e2nd region\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c10\" namest=\"c8\"\u003e\u003cp\u003e3rd region\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003em\u003csub\u003e750\u0026deg;C\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRange\u003c/p\u003e\u003cp\u003e[\u0026deg;C]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eT\u003csub\u003emax1\u003c/sub\u003e\u003c/p\u003e\u003cp\u003e[\u0026deg;C]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eWeight loss\u003c/p\u003e\u003cp\u003e[%]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRange\u003c/p\u003e\u003cp\u003e[\u0026deg;C]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eT\u003csub\u003emax1\u003c/sub\u003e\u003c/p\u003e\u003cp\u003e[\u0026deg;C]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eWeight loss\u003c/p\u003e\u003cp\u003e[%]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eRange\u003c/p\u003e\u003cp\u003e[\u0026deg;C]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eT\u003csub\u003emax2\u003c/sub\u003e\u003c/p\u003e\u003cp\u003e[\u0026deg;C]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eWeight loss\u003c/p\u003e\u003cp\u003e[%]\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"11\" nameend=\"c11\" namest=\"c1\"\u003e\u003cp\u003eN\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;105\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0,7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e185\u0026ndash;381\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e347\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e72,4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e17,2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePT-TW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;105\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0,3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e181\u0026ndash;350\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e315\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e32,2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e350\u0026ndash;456\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e404\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e56,6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e7,0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"11\" nameend=\"c11\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAir\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;104\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2,3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e178\u0026ndash;363\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e311\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e72,9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e363\u0026ndash;424\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e410\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e22,9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e1,6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePT-TW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;102\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0,5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e153\u0026ndash;383\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e324\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e86,7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e383\u0026ndash;451\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e435\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e10,6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e1,7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThese processes are clearly visible on the Derivative Thermogravimetric (DTG) curves. The decomposition of hemicelluloses corresponds to a shoulder at approximately 300\u0026deg;C, while cellulose decomposition corresponds to the main peak at about 350\u0026deg;C. The lignin peak is largely masked by these events due to its low intensity and the broad temperature range over which its decomposition occurs (Yang et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn the case of PT-WT, the mass loss seen on the TG curve is more gradual and occurs over a wider temperature range. This results in a greater total mass loss for the PT-WT samples (approx. 90%) compared to the RW (approx. 73%). PT-WT have a significantly lower char yield (approximately 7%) compared to RW (17.2%). This is due to two factors: the removal of lignin, which is a primary source of char in wood pyrolysis, and the near-complete decomposition of the infiltrated acrylic resin at higher temperatures. The DTG peak near 450\u0026deg;C can be assigned to the decomposition of the resin. For the TW-B sample, this decomposition appears to occur in two distinct stages.\u003c/p\u003e\u003cp\u003eThe resin used is a multi-component system, and the thermal behaviour of its potential components has been described in the literature. For instance, the TGA of poly(2-hydroxyethyl methacrylate) (pHEMA) in a N\u003csub\u003e2\u003c/sub\u003e atmosphere reveals a single decomposition stage between 195\u0026deg;C and 400\u0026deg;C, which leaves approximately 5\u0026ndash;6% of the original mass as a carbonaceous residue (Demirelli et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Another component, dodecyl methacrylate homopolymer, was reported to begin decomposing in air at 150\u0026deg;C, with a total mass loss of 75% by 400\u0026deg;C (Ghosh et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Finally, poly(1,6-hexanediol diacrylate) (pHDDA) degrades in a single step between approximately 300\u0026deg;C and 500\u0026deg;C. Its degradation proceeds via random chain scission and chain-end scission mechanisms, also resulting in a carbon residue (Goswami et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWhen measured in air, two significant changes occur. First, the transparent wood begins to decompose at a temperature approximately 25\u0026deg;C lower, indicating that the resin's decomposition is accelerated by the presence of oxygen. Second, heterogeneous oxidation of the charred residue is visible between 400 and 450\u0026deg;C.\u003c/p\u003e\u003cp\u003eThe TGA data reveal that the individual components of the pHEMA, dodecyl methacrylate homopolymer, and poly(1,6-hexanediol diacrylate) (pHDDA) have distinct thermal degradation profiles. This is crucial because it indicates that the transparent wood composite's overall thermal stability is a combination of these profiles. The degradation of the composite won't occur at a single temperature but rather across a broad range, influenced by the degradation of each component. The composite will likely start to degrade at the lowest temperature of its components, which is the dodecyl methacrylate homopolymer at around 150\u0026deg;C in air.\u003c/p\u003e\u003cp\u003eFurthermore, the TGA results highlight the critical role of the atmosphere (air vs. nitrogen) in the composite's degradation. The observed 25\u0026deg;C drop in the decomposition temperature in air compared to N\u003csub\u003e2\u003c/sub\u003e signifies that oxidative degradation is a major factor. The presence of oxygen catalyses the breakdown of the resin, making the transparent wood composite less thermally stable in an oxygen-rich environment than in an inert one. The final mass loss from the heterogeneous oxidation of the charred residue at 400\u0026ndash;450\u0026deg;C further confirms the composite's vulnerability to oxidative thermal degradation. The material exhibits a thermal profile that aligns with the requirements of various construction and electronics applications, where operational temperatures are not anticipated to exceed its degradation threshold. This characteristic is a vital consideration for its real-world viability, as exposure to elevated temperatures would significantly increase its susceptibility to degradation.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study successfully demonstrated the efficacy of Atmospheric Discharge with Runaway Electrons (ADRE) plasma for modifying the entire volume of bleached and dehydrated wood samples. The unique characteristics of ADRE plasma, particularly its ability to generate high-energy electrons (several tens of keV) at atmospheric pressure, significantly distinguish it from conventional plasma systems. This enables an unparalleled level of material modification and surface property enhancement, such as improved wetting, comparable to low-pressure, near-vacuum discharges, but crucially, without their associated complexity and cost. The developed plasma-based approach markedly enhances the material's optical properties, achieving a high transmittance of up to 91% and notably reducing haze compared to non-plasma-treated composites (72%). This performance represents a substantial improvement over transparent balsa wood prepared with traditional chemical methods.\u003c/p\u003e\u003cp\u003eA key benefit of this innovative method is the complete elimination of harsh organic solvents and chemicals typically used for wood dehydration and interface modification. By bypassing these complex, hazardous, and time-consuming chemical treatments, the proposed method significantly reduces production time, cost, and the overall environmental burden of traditional fabrication. By addressing critical challenges in safety, cost, and environmental impact, this work marks a significant step towards making transparent wood a practical, high-performance, and sustainable material. This streamlined, solvent-free plasma treatment offers a scalable and more environmentally friendly pathway for creating advanced optical bio-composites for energy-efficient smart buildings and other next-generation technologies.\u003c/p\u003e\u003cp\u003eFurther research will focus on optimizing plasma parameters for a broader range of wood species and thicknesses, exploring compatibility with emerging sustainable methods for transparent wood fabrication (e.g., enzymatic delignification, methods using DES), and investigating the scalability of the fabrication process for industrial applications. Additionally, we will investigate bio-based polymer systems that could offer even better performance or specific functionalities, and a detailed assessment of the long-term mechanical and environmental stability of the plasma-treated transparent wood will be crucial for its widespread adoption in various applications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualisation, I.W. and T.Š.; methodology, I.W., A.H., R.T.; software, P.R., T.Š., L.B.,; validation, I.W., T.Š. and P.R.;formal analysis, I.W., T.Š., L.B.;investigation, I.W., P.R.;resources, I.W. and J.M., A.H.;data curation, I.W., T.Š., J.M. and P.R.;writing\u0026mdash;original draft preparation, I.W. and T.Š.;writing\u0026mdash;review and editing, I.W. and T.Š.; visualisation T.Š. and R.T.;funding acquisition, I.W.;All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData is provided within the manuscript or supplementary information files.\u003c/p\u003e\n\u003cp\u003eAcknowledgement\u003c/p\u003e\n\u003cp\u003eFunded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V04-00459\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAlanis, A., Vald\u0026eacute;s, J. H., Mar\u0026iacute;a Guadalupe, N.-V., Lopez, R., Mendoza, R., Mathew, A. P., D\u0026iacute;az de Le\u0026oacute;n, R., \u0026amp; Valencia, L. (2019). Plasma surface-modification of cellulose nanocrystals: a green alternative towards mechanical reinforcement of ABS. \u003cem\u003eRSC Advances\u003c/em\u003e, \u003cem\u003e9\u003c/em\u003e(30), 17417\u0026ndash;17424. https://doi.org/10.1039/C9RA02451D\u003c/li\u003e\n \u003cli\u003eBisht, P., \u0026amp; Pandey, K. K. (2024). \u003cem\u003eDecay resistance and moisture absorption of transparent wood composite\u003c/em\u003e. https://www.scopus.com/inward/record.uri?eid=2-s2.0-85179705209\u0026amp;doi=10.1080%2F17480272.2023.2292287\u0026amp;partnerID=40\u0026amp;md5=fcd3729c4e116b84719b84681601966f\u003c/li\u003e\n \u003cli\u003eCarneiro-Junior, J. A. de M., Oliveira, G. F. de, Alves, C. T., Duro, M. A. I., \u0026amp; Torres, E. A. 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Highly Anisotropic, Highly Transparent Wood Composites. \u003cem\u003eAdvanced Materials\u003c/em\u003e, \u003cem\u003e28\u003c/em\u003e(26), 5181\u0026ndash;5187. https://doi.org/10.1002/adma.201600427\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"cellulose","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cels","sideBox":"Learn more about [Cellulose](https://www.springer.com/journal/10570)","snPcode":"10570","submissionUrl":"https://submission.nature.com/new-submission/10570/3","title":"Cellulose","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Balsa, Modification, Optical properties, Plasma treatment, Transmittance","lastPublishedDoi":"10.21203/rs.3.rs-7426252/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7426252/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTransparent wood is a promising sustainable alternative to glass in construction and technology, but its fabrication is often hindered by the use of harsh chemicals, high costs, and scalability issues. This study introduces a novel, solvent-free method for producing transparent wood by employing a volumetric plasma modification technique. Balsa wood scaffolds were first bleached and then treated using an Atmospheric Discharge with Runaway Electrons (ADRE) plasma, which uniquely modifies the entire material volume, enhancing compatibility with an infiltrating acrylic resin. The resulting plasma-treated transparent wood demonstrated significantly improved optical properties, achieving a high transmittance of 91% at 550 nm, compared to 72% for untreated samples. This enhancement is attributed to improved polymer infiltration and reduced light scattering at the wood-polymer interface. By eliminating the need for hazardous organic solvents and complex chemical treatments, this plasma-based approach offers a more cost-effective, scalable, and environmentally friendly pathway for fabricating high-performance transparent wood. This innovation advances the potential of transparent wood as a practical material for energy-efficient buildings and other advanced applications.\u003c/p\u003e","manuscriptTitle":"Enhancing optical properties of transparent wood by plasma modification","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 08:23:31","doi":"10.21203/rs.3.rs-7426252/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-20T22:50:14+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-20T22:12:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-30T09:04:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Cellulose","date":"2025-08-21T12:25:54+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"cellulose","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cels","sideBox":"Learn more about [Cellulose](https://www.springer.com/journal/10570)","snPcode":"10570","submissionUrl":"https://submission.nature.com/new-submission/10570/3","title":"Cellulose","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"949ebaf2-47da-472b-ab28-b377296aafda","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-30T16:16:17+00:00","versionOfRecord":{"articleIdentity":"rs-7426252","link":"https://doi.org/10.1007/s10570-026-07013-3","journal":{"identity":"cellulose","isVorOnly":false,"title":"Cellulose"},"publishedOn":"2026-03-23 16:08:28","publishedOnDateReadable":"March 23rd, 2026"},"versionCreatedAt":"2025-10-17 08:23:31","video":"","vorDoi":"10.1007/s10570-026-07013-3","vorDoiUrl":"https://doi.org/10.1007/s10570-026-07013-3","workflowStages":[]},"version":"v1","identity":"rs-7426252","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7426252","identity":"rs-7426252","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}