Cellulose Nanocrystal/Polydimethylsiloxane hybrid membranes for air dehydration at elevated temperatures

Cellulose Nanocrystal/Polydimethylsiloxane hybrid membranes for air dehydration at elevated temperatures | 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 Cellulose Nanocrystal/Polydimethylsiloxane hybrid membranes for air dehydration at elevated temperatures Nasim Alikhani, Ling Li, Jinwu Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4716356/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 20 Aug, 2025 Read the published version in Cellulose → Version 1 posted 4 You are reading this latest preprint version Abstract This research study developed a dense composite membrane made of cellulose nanocrystal (CNC) and polydimethylsiloxane (PDMS) to efficiently separate water vapor from air at elevated temperatures up to 80°C. In this study a casting method was used to fabricate CNC/PDMS membranes. The water vapor permeability of the membrane samples was measured with a Payne diffusion cell (dry cup method) coupled with a Dynamic Vapor Sorption (DVS) instrument, while the nitrogen gas permeability was measured with a gas permeation cell. The results showed that the optimal CNC concentration of 2%, enhanced water vapor permeability at all temperatures up to 24.8% while increasing the selectivity slightly up to 3.1%. The membranes were characterized using AFM, FTIR, SEM, and TMA. measured the CTE of the prepared samples to study the dimensional stability as a function of temperature change. The optimized membranes showed an 8.9% lower value for CTE which results in higher thermal dimensional stability of the sample. The results have demonstrated that CNC-reinforced PDMS has potential to be used as selective membranes to remove water vapor from exhaust warm air such that the air recovers its drying capability and can be recirculated as the working medium in drying systems. CNC Membrane Moisture Separation PDMS Permeability Temperature Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. Introduction Recently, membrane separation technology for air dehumidification has become an interesting topic for researchers and industry. Water vapor is separated from the air through a dense membrane without any phase change or temperature change, so this process is also known as an isothermal membrane-based air dehumidification (IMAD) process [ 1 ]. IMAD has been applied in many industries, in which require moisture control during the manufacturing process, such as a drying step in food industries, chemical industries, pharmaceuticals and more [ 2 ], [ 3 ]. Moreover, when it is combined with other units, such as heating, ventilation, and air conditioning (HVAC) units in building systems, pre-air dehumidification could achieve cooling energy saving [ 4 ]. Similarly, it could be a potential energy-saving technology in wood drying processes [ 5 ]. Wood drying is an energy-demanding process that requires heat to warm up the air which circulates through a stack of lumber to remove its moisture [ 6 ]. After absorbing the moisture, the air in dry kilns is saturated and should be vented as exhaust. Fresh and cold air is introduced to the kiln; however, it once again needs extra energy to be heated [ 7 ], [ 8 ]. In contrast, if applying an air dehumidification membrane system to the dry kiln, it could remove the moisture from saturated air without any phase change, thereby allowing the warm air to be recycled into the system, retaining heat. The dehumidified air, which is still at a high temperature, can return to the drying system to run another cycle of drying [ 5 ]. Many polymer-based membrane materials, such as polydimethylsiloxane (PDMS), Polyether-block-amide (PEBAX), and Sulfonated poly(ether ether ketone) (SPEEK), can be used to make a dense membrane for air dehumidification[ 4 ] Among these materials, PDMS is commercially used in IMAD systems because of its low cost, chemical stability, nontoxicity, and good processability. When it is fabricated as a hollow-fiber form, PDMS tubular membranes have a high ratio of surface area to volume and are ease of scale-up[ 5 ], [ 9 ] However, most polymeric materials, including PDMS, are avoided in the working environment with a temperature greater than 50°C. For instance, in the study of flue gas dehydration using PEBAX®1074 and sulfonated SPEEK membrane materials, field tests were carried out when the temperature of flue gas was cooled below 50°C [ 10 ]. In another study, feed gas streams are cooled solely to accommodate a membrane gas separation process, and then they are heated back up [ 11 ]. Reducing the gas temperature and then heating it up add extra cost and energy to the process [ 11 ], [ 12 ]. In most softwood drying processes, the temperature of the air increases up to about 82°C [ 6 ]. Therefore, when testing the suitability of membranes for dehumidifying the exhaust air, it is important to address the influence of temperature on membrane’s performance (permeability and selectivity) instead of solely focusing on thermal stability/degradation analysis [ 13 ]. The performance of polymeric membrane materials can be improved by adding nanomaterials [ 12 ], ZnO [ 14 ], TiO 2 [ 15 ], SiO 2 [ 16 ], titanate nanotubes (TNTs) [ 17 ], Zeolite [ 18 ], [ 19 ] and more. However, most of these nanoparticles are non-sustainable and in some cases are petroleum based. Cellulose nanocrystal (CNC), a class of nanomaterials with dimensions of 100–300 nm long and 5–70 nm in diameter derived from sustainable and renewable lignocellulosic biomass, can solve environmental problems related to other inorganic nanoparticles by serving as nature's storage for carbon dioxide. It has many attractive features, such as large specific surface area, high tensile strength and stiffness, abundance of surface hydroxyl groups, extremely low coefficient of thermal expansion (CTE), and more [ 20 ]–[ 23 ]. So, it has been used to substitute for inorganic nanoparticles (such as TiO 2 , Al 2 O 3 ) in film-type composites as reinforcement fillers to improve the strength, thermal expansion stability, optical property, etc. of the composites [ 24 ]. When the solution-diffusion mechanism governs gas diffusion in the dense polymeric membranes, the gas molecules dissolve into a membrane, diffuse across the membrane thickness, and then desorb from the other side of the membrane [ 5 ]. This study aimed to develop a high-performance hybrid composite membrane for air dehumidification at elevated temperatures for wood drying applications. CNC was chosen as an additive to PDMS because of two hypotheses: 1) the surface hydroxyl groups of CNC could increase the moisture adsorption sites in the PDMS membrane to improve the solubility of water vapor on the membrane surface and create a large water vapor concentration difference for a fast diffusion and 2) CNC's low thermal expansion attribute could restrain the PDMS thermal expansion at elevated temperatures if CNCs disperse in PDMS uniformly. To achieve the goal, four objectives of this study were to 1) synthesize CNC/PDMS membranes using CNC suspension with four concentrations (0%, 2%, 4%, and 6%); 2) measure the water vapor permeability, nitrogen gas permeability, their selectivity, and coefficient of thermal expansion of the membrane samples at three different temperatures (25°C, 50°C, and 80°C); 3) characterize the morphology of the membrane samples, and 4) determine the optimal CNC concentration for making a high-performance CNC/PDMS composite membrane. 2. Materials and Methods 2.1 Materials PDMS prepolymer and curing agent kits (Dow SYLGARDTM 184 Silicone Elastomer kit) were purchased from Dow Inc. (MI, USA). A CNC suspension at 11.8% solids was purchased from the USDA Forest Products Laboratory, distributed by the Process Development Center of the University of Maine (ME, USA). CNCs were subjected to comprehensive characterization in a previous study [ 25 ]. The results of the study revealed that the CNC particles had an average length of 134 ± 52 nm and a width of 7 ± 2 nm. The aspect ratio of the particles was determined to be 19. Additionally, the study reported a sulfate half-ester (-OSO 3 − ) content of 335 mmol kg − 1 for the CNCs. 2.2 Methods 2.2.1 Synthesis of membranes The PDMS prepolymer and curing agent at the ratio of 10:1 by weight (e.g., 10 grams of PDMS prepolymer and 1 gram of curing agent) was mixed mechanically for 5 minutes at room temperature. The solution was degassed for 45 seconds with a planetary centrifugal bubble free mixer (THINKY ARE-310, Tokyo, Japan). Then the solution was cast on a Teflon plate using a casting knife. The wet film had a nominal thickness of 150 µm. The wet film was cured in an oven at 50°C for 24 h. The pure PDMS was used as control group (i.e., 0% CNC). For making CNC/PDMS membranes, ten (10) grams of the PDMS prepolymer and 1 gram of the curing agent were mixed mechanically for 5 minutes at room temperature. Appropriate amount of CNC suspension was added to the 11-gram solutions to achieve the CNC solid concentrations of 2%, 4%, and 6% in total solids, respectively. The mixture was then mechanically mixed for 1 hour, degassed for 45 seconds, and cast on a Teflon plate using a casting knife to obtain a wet membrane with a nominal thickness of 130 and 150 µm for Pure PDMS and CNC/PDMS films, respectively [ 26 ], [ 27 ]. The wet membranes were first dried at room temperature in a vacuum desiccator with a vacuum pressure of 88 kPa for 1 hour, intended to remove any remaining air bubbles in the wet membranes. After that, the semi-cured membranes were transferred to an oven and cured at 50°C for 24 h [ 26 ]. The thickness of dry film samples was measured using a digital micrometer (Mitutoyo, IL, USA) with an accuracy of 0.001 mm. Multiple measurements were performed to determine the average thickness of the film samples. 2.2.2 Scanning electron microscopic (SEM) analysis The morphology of the CNC/PDMS membrane samples was observed using a scanning electron microscope (SEM) (NVision 40, Zeiss, Germany). The sample was placed on a specimen mount using carbon tape and then was coated with conductive silver. The regions of interest of the sample were sputter coated with gold (23 nm) using a Cressington 108 auto sputter coater (Ted Pella Inc., Redding, CA, USA). The images were taken at an accelerating voltage of 3 kV. 2.2.3 Atomic Force Microscopy (AFM) analysis The PDMS and CNC/PDMS samples were cut into 5 mm x 5 mm areas for observation on an AFM (MFP-3D, Oxford Instruments Oxon, UK). Images were collected with an AC200TS-R3 probes with 9 ± 6 (nN/nm) spring constants. Alternating current mode produced images with a set point of (0.4 V) and constant free air amplitude of (1 V). 2.2.4 ATR-FTIR analysis The ATR-FTIR analysis was performed using a PerkinElmer Spectrum Two™ FTIR spectrometer (Shelton, CT, USA) to evaluate the nature of the interaction between the CNCs and PDMS in the membranes. Each sample was measured at a resolution of 4 cm − 1 . The data were obtained under an accumulation of 16 scans in the range of 450–4000 cm − 1 . 2.2.5 Measurement of water vapor permeability of membranes The water vapor transmission rate (WVTR) was measured using a dynamic vapor sorption (DVS) instrument (Model: DVS Advance; Surface Measurement Systems, London, UK) as shown in Fig. 1 . The sample was placed to seal a Payne cell. Silicone gel beads were placed in the cell to absorb water vapor that entered the cell to maintain a 0% RH in the headspace. The surrounding environment of the Payne cell was controlled by DVS to desired testing conditions. For each sample type, nine (9) replicates cut from three same membranes were tested. The thickness of each sample was measured using a digital micrometer. Each sample was tested at 25°C, 50°C, and 80°C and a constant RH of 60%. The increase of mass of the Payne cell assembly with time was recorded simultaneously. The tests followed the ASTM E96 Standard test method for water vapor transmission of materials (ASTM 2016). The H 2 O permeability ( P H2O ) was calculated using Eq. ( 1 ): $$\:{P}_{{H}_{2}O}=\frac{WVTR\times\:{T}_{mem}}{\:{\varDelta\:}_{Vapor\:pressure}}=\frac{\left(\varDelta\:m/\varDelta\:t\right)\times\:{T}_{m}}{A\times\:\varDelta\:p\times\:18}\:\:\left(\frac{mol}{m\bullet\:s\bullet\:Pa}\right)\:$$ 1 Where, Δm/Δt is the slope of a linear section of the mass versus time, g/s; T m is the thickness of the sample membrane, m; A is the open area of the Payne cell, 1.18^10 − 4 m 2 ; Δp is the partial pressure difference of water vapor, \(\:\varDelta\:p=\frac{\varDelta\:RH}{100}\times\:Saturated\:water\:pressure\) at 25°C,50°C, and 80°C, Pa (Saturated water vapor pressure at 25°C = 3171 Pa, 50°C = 12351 Pa, 80°C = 47415 Pa);18 g/mol is the molecular weight of H 2 O. 2.2.6 Measurement of nitrogen gas permeability of membranes The pure nitrogen gas transmission rate (NGTR) was measured using a single gas transmission cell (Custom Scientific Instruments Inc, PA, USA) as shown in Fig. 2 , following the ASTM D1423-82(2015) Standard test method for determining gas permeability characteristics of plastic film and sheeting (ASTM 2015). Samples were cut into circles with a diameter of 0.12 meter thickness was recorded. One sample was mounted to separate the cell into the upper and lower chambers. Compressed nitrogen gas flowed into the lower chamber, diffused through the sample, and entered the upper chamber. The volume expansion of the upper chamber was measured by recording the movement of a liquid color slug in the capillary tube. Nine (9) replicates for each sample type were tested. The transmission cell was placed in a water bath to maintain the desired temperatures of 25°C, 50°C, and 80°C. The pressure difference between the lower chamber and upper chamber was measured by a pressure gauge. The N 2 gas permeability was calculated using Eq. ( 2 ): $$\:{P}_{{N}_{2}}=\frac{NGTR\times\:{T}_{m}}{\varDelta\:p}=\:\frac{{P}_{0}\:\times\:\:S\times\:\pi\:{D}^{2}\times\:{T}_{m}}{\varDelta\:p\times\:4\:A\:R\:T}\:\:\:\:\:\:\:\:\:\:\:\left(\frac{mol}{m\bullet\:s\bullet\:Pa}\right)\:$$ 2 Where P 0 is the ambient pressure, 101325 Pa, S is the rate of rising of the capillary slug (m/s); D is the capillary tube’s inner diameter, 0.4957^10 − 3 m; A is the open area of the cell, 0.6655^10 − 2 m 2 ; T m is the thickness of the sample membrane, m; Δp is the pressure difference between the lower and upper chamber, i.e., gauge pressure, Pa; T is the temperature of gas, K; R is the gas constant (8.3143 m 3 .Pa/(mol.K)). 2.2.7 Calculation of Selectivity of water vapor and nitrogen The selectivity (α) was obtained from the ratio of H 2 O to N 2 permeability, Eq. ( 3 ). $$\:\alpha\:=\:\frac{{P}_{{H}_{2}O}}{{P}_{{N}_{2}}}$$ 3 2.2.8 Measurement of coefficient of thermal expansion (CTE) The in-plane coefficient of thermal expansion (CTE) of the PDMS and CNC/PDMS membrane samples were measured using a thermomechanical instrument (Q400 TMA, TA Instrument). Samples were cut into 5 mm × 5 mm areas and one sample at a time was sandwiched between two crystal wafers to ensure force dispersion. An expansion probe rested on the surface of the samples with a 0.02 N preload. As the temperature was raised from 25°C to 100°C a heating rate of 5°C/min, the change in thickness of the sample was recorded, allowing the calculation of CTE from the slope of the resulting expansion temperature plots. CTE is calculated using Eq. 4 [ 23 ]. $$\:CTE=\:\frac{\varDelta\:L}{{L}_{0}\:\times\:\:\varDelta\:t}$$ 4 Where L 0 is the initial length of the sample (µm); Δt is the temperature change (° C), and ΔL is the thermal expansion (or contraction) of the sample after the temperature change. For each concentration, 3 samples were prepared and tested, where performed in triplicate. Therefore, the average of Nine (9) replicates for each sample type were measured and reported. 2.2.9 Statistical analysis Two-way analysis of variance (ANOVA) was performed for two independent variables (CNC concentration and temperature) to understand the main effects and interaction effects of them on the water vapor and nitrogen gas permeability, and selectivity of the membrane samples. One-way ANOVA was conducted for the effect of the independent variable (CNC concentration) on CTE. All statistical analyses were run in OriginPro software version 2022b, with a level of significance of 0.05 [ 28 ]. 3. Results 3.1 Appearance and morphology of CNC/PDMS membrane samples The appearance of four types of membrane samples is provided in Fig. 3 . The Pure PDMS has the highest transparency, and the transparency of the film is decreased with increasing the CNC concentration. The SEM images (Fig. 4) show the top surface morphology of four membrane samples. The dispersion of CNC in PDMS is dependent on the concentration of CNC added. CNC particles are relatively small and distributed randomly in PDMS when 2% of CNC was added. In contrast, when the concentration of CNC was increased to 4% and 6%, the CNC aggregation became more significantly distinctive. In addition, these SEM images show the PDMS and CNC/PDMS membranes are dense membranes, and no pores or defects are observed at this level of magnification. AFM images (Fig. 5 ) were used to estimate the 3D shape and dimensions of CNC nanoparticles agglomerations. Most of the CNC particles have a height in the range of 10 nm to 100 nm. The maximum height of agglomerated CNC particles could reach over 100 nm. More high peaks are observed with the increase in CNC concentration. 3.2 ATR - FTIR analysis Figure 6 shows the FTIR spectra of an air-dried CNC film (Control-1), pure PDMS sample (Control-2), and CNC/PDMS samples with CNC concentrations of 2%, 4%, and 6%. For Control-1 CNC film, a strong O-H stretching vibration at 3332 cm − 1 and bending band of H-O-H bond at 1638cm − 1 are observed [ 29 ], [ 30 ]. For Control-2 PDMS membrane, the featured peaks of PDMS include 2960 cm − 1 for CH 3 group vibration, 1257 cm − 1 for the symmetric deformation of the CH 3 group, 887 cm − 1 for Si-C vibration, and 790 cm − 1 for Si-O vibration [ 31 ]. When low concentrations of CNCs were blended in PDMS, the spectra of CNC/PDMS samples show that peaks at 3332 cm − 1 and 1638cm − 1 almost disappeared but the peak at 1057 cm − 1 representing the stretching vibrations of C-O in CNC became slightly distinctive [ 30 ]. The results reveal that the addition of CNC from 2–6% did not change the general spectra pattern of CNC/PDMS samples. Therefore, the performance of CNC/PDMS membrane is mainly governed by the PDMS. 3.3 Permeability of water vapor The values of water vapor permeability (Fig. 7 ) increased with the CNC concentration from 0% (pure PDMS) to 2% and then decreased. The mean ± SD values of water vapor permeability at 25°C for Pure PDM, 2% CNC/PDMS, 4% CNC/PDMS, and 6% CNC/PDMS were 30,683.6 ± 615.9, 38,295.6 ± 1,070.9, 35,883.6 ± 1,248.8, and 35,846.1 ± 1,338.3 Barrer, respectively. The addition of 2% CNC resulted in an increase of 24.8%, 30.9%, and 11.2% at 25°C, 50°C, and 80°C, respectively. Higher concentrations of CNC (4% and 6%) show a slightly decreasing trend for water vapor permeability, while the permeability values remained higher than those for pure PDMS membranes. This trend is the same in all three temperatures except for 80°C. When the temperature increased from 25°C to 80°C, the permeability of water vapor decreased dramatically. Two-way ANOVA results reveal that the effects of CNC concentration, temperature and their interaction on water permeability were statistically significant (Table A.1 Supplementary document). Furthermore, the comparison between different CNC concentrations shows that the 2% CNC/PDMS is significantly different from other samples, but there is not any significant difference between pure PDMS (0% CNC), 4% CNC/PDMS, and 6% CNC/PDMS samples (Table A.2 ). Therefore, 2% CNC is the optimal concentration in terms of water vapor permeability. 3.4 Permeability of nitrogen gas The values of Nitrogen gas permeability (Fig. 8 ) increased with the CNC concentration from 0% (pure PDMS) to 2% and then slightly decreased. The mean ± SD values of Nitrogen gas permeability at 25°C for Pure PDM, 2% CNC/PDMS, 4% CNC/PDMS, and 6% CNC/PDMS were 263.7 ± 4.6, 324.9 ± 18.7, 310.0 ± 8.4, and 310.3 ± 7.3 Barrer, respectively. The nitrogen gas permeability (Fig. 8 ) was increased by 23.2%, 27.8%, and 16.0% at three temperatures when adding 2% CNC to the PDMS membrane. Similarly, higher concentrations of CNC (4% and 6%) show a slightly decreasing trend for nitrogen permeability compared with 2% CNC. The nitrogen permeability increased as the temperature was elevated from 25°C to 80°C. Two-way ANOVA results show the effect of CNC concentration on nitrogen permeability was not statistically significant but the effect of temperature on permeability was statistically significant (Table A.3 ). The interaction between temperature and concentration was not statistically significant either. Furthermore, the comparison between different CNC concentrations reveals that there was not a statistically significant difference between 2%, 4%, and 6% CNC/PDMS membranes but all the CNC/PDMS were significantly different from the Pure PDMS (Table A.4 ). Therefore, 2% CNC is the optimal concentration in terms of nitrogen gas permeability. 3.5 Selectivity of water vapor and nitrogen The selectivity of water vapor over nitrogen (Fig. 9 ) at 25°C of pure PDMS, 2%CNC/PDMS, 4%CNC/PDMS, and 6%CNC/PDMS were 116.3, 117.9, 115.7, and 115.5, respectively. A slight increase of about 3.1% was observed at 2% CNC addition, followed by a slight decrease when increasing the concentration of CNC at three temperatures. Two-way ANOVA results (Table A.5 ) show that the effect of CNC concentration on selectivity was not statistically significant but the effect of temperature on selectivity was statistically significant. The interaction between temperature and concentration was not statistically significant for selectivity. 3.6 Coefficient of thermal expansion (CTE) of membranes The dimensional stability of CNC/PDMS membranes influences how well the membrane operates at elevated temperatures. It was evaluated in terms of the coefficients of thermal expansion (CTE) of pure PDMS and CNC/PDMS membranes (Fig. 10 ). The mean ± SD of CTE for pure PDMS, from room temperature up to 100°C, was 301.1 ± 12.6 µm/m.°C. This measured value is in good agreement with the published values for CTE of PDMS which is 309 ppm/°C [ 32 ]. After adding 2% CNC, the mean ± SD of CTE was reduced to 274.4 ± 8.5 µm/m.°C, which is about 12% lower than that of pure PDMS. This decrease in CTE was expected because CNC has a very low CTE of 9 µm/m.°C [ 33 ]and it helps to restrain the expansion of PDMS at elevated temperatures when CNCs are dispersed in PDMS [ 23 ]. However, the mean ± SD of CTE of 4% CNC/PDMS and 6% CNC/PDMS was 269.5 ± 13.2 and 264.3 ± 8.6, respectively. Increasing the CNC concentration to 4% and 6% did not further decrease the CTE greatly. One-way ANOVA results (Table A.6 ) show that the decrease in the CTE between pure PDMS sample and 2% CNC/PDMS sample was statistically significant. Also, the comparison between different CNC concentrations (Table A.7 ) shows that there is not a significant difference between 2%, 4% and 6% CNC/PDMS samples and all these samples are significantly different from Pure PDMS. Once again, 2% CNC is the optimal concentration in terms of CTE. 4. Discussion 4.1 Influence of CNC agglomeration on membrane appearance and properties When CNC suspension was mechanically mixed with the PDMS prepolymer and curing agent solution and then dried until fully cured, CNC agglomeration occurred due to the poor compatibility of hydrophilic CNC and hydrophobic PDMS. When more agglomerated CNC particles were formed as the increase of CNC concentration, the membrane transparency decreased ascribed to the mismatch of refractive indexes between CNC and PDMS. Combined SEM and AFM images, the CNC particles are present on the membrane surface with needle-like shapes. The water vapor and nitrogen gas permeability, and CTE results of CNC/PDMS membrane samples show that 2% CNC was the optimal concentration. Increasing the CNC concentration were not further enhancing the membrane performance. The reason is also explained by the poor compatibility. The compatibility of CNC and PDMS might be improved by modifying the CNC, such as the silylation of CNC [ 26 ], [ 27 ] 4.2 Effects of temperature on permeability of water vapor and nitrogen gas Gas transport through dense polymeric membranes is governed by the solution-diffusion mechanism. Therefore, the effects of temperature on both solution and diffusion processes should be considered. The influence of temperature on solubility has been well addressed in terms of the van't Hoff relationship. Gas solubility correlates with its condensability. For less condensable gases (e.g., N 2 and O 2 ) that often have lower critical temperatures (Table 1), gas solubility increases with an increase in the temperature. However, for condensable gases and vapors (e.g., water vapor) solubility decreases with increasing temperature [ 11 ], [ 34 ]. The diffusion of gas molecules in a dense membrane is a thermally activated process and increases as the temperature increases, which is well described by the Arrhenius equation [ 34 ] However, for water vapor permeability, sorption is the preponderant factor [ 35 ], Which means the magnitude of solubility change is greater than that of diffusivity change (because of high condensability which correlates with the high critical temperature as shown in Table. 1), thereby resulting in a decrease in permeability. This explains why water vapor permeability decreases, as illustrated in Fig. 7 , when the temperature increases from 25°C to 80°C. However, for the N 2 and O 2 molecules which are larger in kinetic diameter and less condensable, while increasing the temperature, there is increase in both the diffusivity and the solubility. This leads to an increase in permeability [ 11 ] This phenomenon is evident in the increased nitrogen gas permeability when the temperature rises from 25°C to 80°C, as shown in Fig. 8 . 4.3 Effectiveness of CNC as a nanofiller on water vapor and nitrogen gas permeability In this study, a bio-based material CNC was used as a nano filler in the PDMS matrix to improve the PDMS membrane performance for air dehydration, to the best of our knowledge, which is the first time to report this type of application of CNC. CNC’s renewable and sustainable features make it possible as alternatives to non-renewable nanofillers, like zeolites (ZIF), silicon dioxide (SiO 2 ), and titanate nanotubes (TNTs), reported in the previous studies [ 16 ]–[ 19 ]. While in most of the other studies regarding mixed matrix membranes, the nano filler they used in PDMS is not bio based and not renewable. The CNC used in this study is renewable and can be produced from sustainable sources, two features that make it superior to other nano particles such as zeolites (ZIF). On the other hand, to the best of our knowledge, this is the first time to make a mixed matrix membrane with PDMS for improving water vapor permeability of PDMS. Our study revealed that the water vapor permeability and nitrogen permeability of PDMS membrane at room temperature were found to be 3,683 Barrer and 263 Barrer, respectively, consistent with previous studies [ 37 ], [ 38 ]. After adding the optimal concentration of 2% CNC, the water vapor and nitrogen gas permeability at room temperature were increased by 24.8% and 23.5 %, respectively. I the study conducted by Mao et al. (2012), the addition of approximately 30 wt.% of ZIF-L to PDMS led to a significant 8.0% increase in water vapor permeability at 40°C [ 18 ]. Similarly, Sahin et al. (2020) conducted another study where they added 20 wt.% of ZIF-71 to PDMS and observed a significant enhancement of around 34% in the permeability of nitrogen gas at 35°C [ 19 ]. CNCs have demonstrated several benefits in comparison to ZIF nanoparticles. For instance, they require a significantly lower weight ratio to achieve a similar improvement in water vapor and nitrogen gas permeability. Beltran et al. reported an increase in the gas permeability of PDMS after adding modified SiO 2 , due to the increase in the free volume of the membrane [ 16 ]. Such an increase in free volume led to an increase in the diffusion coefficient. These findings suggested that PDMS, a rubbery polymer, may exhibit an increase in free volume upon the incorporation of nonporous fillers of SiO 2 [ 16 ]. Li et al. (2010) found that adding TNTs into the PDMS matrix resulted in a significant enlargement of the fractional free volume (FFV)[ 17 ]. The enlargement of the FFV created more diffusion paths for small penetrants, and consequently, increased the gas permeability of the nanocomposite membranes. In this study, the effectiveness of CNC on the enhancement of water vapor and nitrogen gas permeability could be also explained by the modified FFV. 5. Conclusions In this study, CNC/PDMS membranes with the CNC weight concentrations of 0%, 2%, 4%, and 6% were successfully synthesized. The samples were defect-free and contained no observable pores under microscopic imaging because of the degassing step during preparation. The SEM images and AFM results revealed the CNC nanoparticles were dispersed in the PDMS matrix either randomly or in small agglomerations depending on CNC concentrations. The FTIR spectra confirmed the existence of CNCs in the CNC/PDMS samples. The addition of CNC alters the permeability and selectivity of the membranes. The optimal CNC concentration was 2% with enhanced water vapor permeability at all temperatures up to 24.8% while increasing the selectivity slightly up to 3.1%. In addition, the 2% CNC/PDMS samples showed an 8.9% lower value for CTE which results in higher thermal dimensional stability of the sample. The future work would be the modification of CNCs, e.g., silylation, to increase the compatibility between CNCs and PDMS polymer and increase the dispersion of CNCs in the PDMS matrix. Declarations Acknowledgement: This project was supported by the USDA National Institute of Food and Agriculture, McIntire-Stennis (Project number ME0-42205) through the Maine Agricultural & Forest Experiment Station; the U.S. Department of Agriculture’s Agricultural Research Service (USDA ARS Agreement No. 58-0204-6-003 & No. 58-0204-9-166); the US Forest Service and US Endowment for Forestry and Communities-P3Nano Advancing Commercialization of Cellulose Nanomaterials (Agreement 21-00166). In addition, authors would like to thank Dr. Elliot Sanders for help with the AFM testing and iLab UMaine for help to prepare SEM images. Funding This project was supported by the USDA National Institute of Food and Agriculture, McIntire-Stennis (Project number ME0-42205) through the Maine Agricultural & Forest Experiment Station; the U.S. Department of Agriculture’s Agricultural Research Service (USDA ARS Agreement No. 58-0204-6-003 & No. 58-0204-9-166); the US Forest Service and US Endowment for Forestry and Communities-P3Nano Advancing Commercialization of Cellulose Nanomaterials (Agreement 21-00166). Conflict of interest/Competing interests This work has no conflicts of interest to disclose. Ethics approval and consent to participate Not applicable. This study did not involve human or animal subjects. Consent for publication All the images and tables presented in this work are original results. Content adopted from other works has been cited carefully. Data availability All research data is included in the article. Authorship Contributions Nasim Alikhani: Methodology, Running tests, Visualization, Writing original draft. Ling Li: resources, writing – review and editing, and funding acquisition. Jinwu Wang: resources, writing – review and editing, and funding acquisition. References S. Zhao et al. , “Simultaneous heat and water recovery from flue gas by membrane condensation: Experimental investigation,” Appl Therm Eng, vol. 113, pp. 843–850, Feb. 2017, doi: 10.1016/j.applthermaleng.2016.11.101 . M. Qu, O. Abdelaziz, Z. Gao, and H. Yin, “Isothermal membrane-based air dehumidification: A comprehensive review,” Renewable and Sustainable Energy Reviews, vol. 82, pp. 4060–4069, Feb. 2018, doi: 10.1016/J.RSER.2017.10.067 . G. P. Thiel and C. Atkinson, “The potential for energy savings in U.S. houses by using isothermal dehumidification,” Sci Technol Built Environ, vol. 27, no. 6, pp. 776–787, 2021, doi: 10.1080/23744731.2021.1879564 . D. Bergmair, S. J. Metz, H. C. De Lange, and A. A. 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Research, “Comparison of permeability performance of PEBAX-1074/TiO2, PEBAX-1074/SiO2 and PEBAX-1074/Al2O3 nanocomposite membranes for CO2/CH4,” Chemical Engineering Research, 2017. M. S. Reid, M. Villalobos, and E. D. Cranston, “Benchmarking Cellulose Nanocrystals: From the Laboratory to Industrial Production,” Langmuir, vol. 33, no. 7, pp. 1583–1598, Feb. 2017, doi: 10.1021/ACS.LANGMUIR.6B03765 . M. Planes, J. Brand, and S. Lewandowski, “Improvement of the thermal and optical performances of protective polydimethylsiloxane space coatings with cellulose nanocrystal additives,” Applied Materials and Interfaces , 2016, Accessed: Feb. 26, 2022. [Online]. Available: https://pubs.acs.org/doi/abs/10.1021/acsami.6b09043 T. Xia, H. Yuwen, and N. Lin, “Self-bonding sandwiched membranes from PDMS and cellulose nanocrystals by engineering strategy of layer-by-layer curing,” Compos Sci Technol, 2018. OriginLab Corporation, “Origin(Pro).” Northampton, MA, USA., 2022. E. Inácio, D. Souza, and M. D. Applications, “Thermal and crystallization behavior of PLA/PLLA-grafting cellulose nanocrystal,” Materials Sciences and Applications , 2020, Accessed: Feb. 26, 2022. [Online]. Available: https://www.scirp.org/html/4-7702507_97682.htm T. Jayaramudu, H. Ko, H. Kim, J. Kim, and M. RM, “Electroactive hydrogels made with polyvinyl alcohol/cellulose nanocrystals,” Materials , 2018, Accessed: Feb. 26, 2022. [Online]. Available: https://www.mdpi.com/335546 X. Cui, G. Zhu, Y. Pan, Q. Shao, M. Dong, and Y. Zhang, “Polydimethylsiloxane-titania nanocomposite coating: fabrication and corrosion resistance,” Polymer (Guildf), vol. 138, 2018. A. Müller, M. C. Wapler, and U. Wallrabe, “A quick and accurate method to determine the Poisson’s ratio and the coefficient of thermal expansion of PDMS,” Soft Matter , vol. 15, no. 4, pp. 779–784, Jan. 2019, doi: 10.1039/C8SM02105H . J. A. Diaz, X. Wu, A. Martini, J. P. Youngblood, and R. J. Moon, “Thermal Expansion of Self-Organized and Shear-Oriented Cellulose Nanocrystal Films,” 2013, doi: 10.1021/bm400794e . B. W. Rowe, L. M. Robeson, B. D. Freeman, and D. R. Paul, “Influence of temperature on the upper bound: Theoretical considerations and comparison with experimental results,” J Memb Sci , vol. 360, no. 1–2, pp. 58–69, Sep. 2010, doi: 10.1016/J.MEMSCI.2010.04.047 . A. S. Spatafora Salazar, P. A. Sáenz Cavazos, H. Mújica Paz, and A. Valdez Fragoso, “External factors and nanoparticles effect on water vapor permeability of pectin-based films,” J Food Eng , vol. 245, pp. 73–79, Mar. 2019, doi: 10.1016/J.JFOODENG.2018.09.002 . S. J. Metz, “WATER VAPOR AND GAS TRANSPORT THROUGH POLYMERIC MEMBRANES,” Nov. 2003. Accessed: Feb. 05, 2021. [Online]. Available: https://research.utwente.nl/en/publications/water-vapor-and-gas-transport-through-polymeric-membranes M. Leemann, G. Eigenberger, H. S.-J. of M. Science, and undefined 1996, “Vapour permeation for the recovery of organic solvents from waste air streams: separation capacities and process optimization,” Elsevier , Accessed: Apr. 25, 2023. [Online]. Available: https://www.sciencedirect.com/science/article/pii/0376738895001301 S. Koester, F. Roghmans, M. W.-J. of M. Science, and undefined 2015, “Water vapor permeance: The interplay of feed and permeate activity,” Elsevier , Accessed: Apr. 25, 2023. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S0376738815001957 Tables Table 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Tables.docx Graphicalabstract.docx Cite Share Download PDF Status: Published Journal Publication published 20 Aug, 2025 Read the published version in Cellulose → Version 1 posted Editorial decision: Revision requested 11 Oct, 2024 Editor assigned by journal 11 Oct, 2024 Submission checks completed at journal 24 Sep, 2024 First submitted to journal 10 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4716356","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":371378370,"identity":"0266fad5-d720-4fa0-823c-acb25525ebef","order_by":0,"name":"Nasim Alikhani","email":"","orcid":"","institution":"University of Maine","correspondingAuthor":false,"prefix":"","firstName":"Nasim","middleName":"","lastName":"Alikhani","suffix":""},{"id":371378371,"identity":"68b4ee81-a791-426b-9678-12d4a66e4f3d","order_by":1,"name":"Ling Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAw0lEQVRIiWNgGAWjYBACPmYQWSAhx8DA2ABiQkh8gA2sxUDCmAQtYNKAIRGmkggt7LyHXzAYWKSvbT/c9uADg43shgMEHcaXZgF0WO62M4nthjMY0oyJ0MJjZgDWciCxTZqH4XAi0VrSzc4/bJP+w/CfKC3GD4BaEsxuAG1hYDhAnC0MCQYShttuPGyT7DFINp5JSAs//xnjDx8q6uTNzqc/k/hRYSfbR0gLyCKJBDjbgLByEGD+QJy6UTAKRsEoGLEAAKWnOnHrFQGJAAAAAElFTkSuQmCC","orcid":"","institution":"University of Maine","correspondingAuthor":true,"prefix":"","firstName":"Ling","middleName":"","lastName":"Li","suffix":""},{"id":371378372,"identity":"43b9fa2c-a8c6-4a8a-9846-bfa9965ecf58","order_by":2,"name":"Jinwu Wang","email":"","orcid":"","institution":"Forest Products Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Jinwu","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2024-07-10 07:37:46","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4716356/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4716356/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10570-025-06707-4","type":"published","date":"2025-08-20T16:29:43+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":67881245,"identity":"cf9b2c12-d372-4474-813d-b4514e7c303c","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":44680,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic of the WVTR test setup on a dynamic vapor sorption instrument (dry cup) indicating a test sample is sealed on the top of the Payne cell\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/ef82738aba12aabf98a427aa.jpg"},{"id":67881249,"identity":"4f3dda44-5809-43a0-9a6c-1bfccd123e36","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":59639,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic of a single gas transmission cell\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/c2696322e543b729faa1ff5b.jpg"},{"id":67881246,"identity":"46e0f046-a98e-481e-9901-f3446785851b","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":55049,"visible":true,"origin":"","legend":"\u003cp\u003eAppearance of the membrane Samples\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/9abe60315f887da32f79d842.jpg"},{"id":67882295,"identity":"39d5fb8c-c8a7-43db-bd7b-b52b61158d6a","added_by":"auto","created_at":"2024-10-30 17:12:36","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":123132,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eSEM images of hybrid membrane materials of CNC/PDMS: (a) 0%, (b) 2%, (c) 4%, and (d) 6%. CNCs appear as various-sized particles\u003c/em\u003e\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/3540d9a1190611d9fa060883.jpg"},{"id":67881255,"identity":"92ebbae3-2108-4795-87cf-7e261b89fb88","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":65146,"visible":true,"origin":"","legend":"\u003cp\u003e3D images of AFM results of hybrid membrane materials (a) Pure PDMS, (b) 2% CNC/PDMS, (c) 4% CNC/PDMS, and (d) 6% CNC/PDMS.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/f1f2d965c5feb9d2b00ba646.jpg"},{"id":67881250,"identity":"e460867e-72ce-4c7f-b35e-411839ea5884","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":59562,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of all membrane samples and control groups\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/67413f2f5169e1271ae6e3f8.jpg"},{"id":67881254,"identity":"44132150-c8d6-4966-9b63-44417a6e23ae","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":216717,"visible":true,"origin":"","legend":"\u003cp\u003eWater vapor permeability at elevated temperatures and a humidity differential of 60%\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/fcc2539945edcb92a9e988e7.jpg"},{"id":67881252,"identity":"d8bc6bba-edbe-4b0c-a4b0-2a9443f2fc90","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":256506,"visible":true,"origin":"","legend":"\u003cp\u003eNitrogen permeability at the elevated temperatures\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/5b0a36239f9dfb84203548c9.jpg"},{"id":67881256,"identity":"9ea1dd5f-ffb8-41c5-96b3-ea1197824d76","added_by":"auto","created_at":"2024-10-30 17:04:36","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":256036,"visible":true,"origin":"","legend":"\u003cp\u003eSelectivity of H\u003csub\u003e2\u003c/sub\u003eO/N\u003csub\u003e2\u003c/sub\u003e at elevated temperatures\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/203b17e6829e1021bd1196a0.jpg"},{"id":67882298,"identity":"d9de839a-f4ab-4731-b128-c37ecaca91cf","added_by":"auto","created_at":"2024-10-30 17:12:36","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":58297,"visible":true,"origin":"","legend":"\u003cp\u003eThe CTE values for different samples\u003c/p\u003e","description":"","filename":"10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/082d4faf4d78a04cf341d44a.jpg"},{"id":89847273,"identity":"7eb3692e-895b-46f0-842d-911586b5d7ec","added_by":"auto","created_at":"2025-08-25 16:42:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2202050,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/35b811eb-01cc-4955-8aa3-0e75c9629e84.pdf"},{"id":67882296,"identity":"acc6742c-7a03-45c9-afb7-c260297f6f54","added_by":"auto","created_at":"2024-10-30 17:12:36","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":171843,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/aa74cc4cc620babee2ab3caf.docx"},{"id":67882297,"identity":"a612fa02-8479-489d-befa-31e9714dcfac","added_by":"auto","created_at":"2024-10-30 17:12:36","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":712560,"visible":true,"origin":"","legend":"","description":"","filename":"Graphicalabstract.docx","url":"https://assets-eu.researchsquare.com/files/rs-4716356/v1/fdd8e170d97c871629ed5438.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Cellulose Nanocrystal/Polydimethylsiloxane hybrid membranes for air dehydration at elevated temperatures","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eRecently, membrane separation technology for air dehumidification has become an interesting topic for researchers and industry. Water vapor is separated from the air through a dense membrane without any phase change or temperature change, so this process is also known as an isothermal membrane-based air dehumidification (IMAD) process [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. IMAD has been applied in many industries, in which require moisture control during the manufacturing process, such as a drying step in food industries, chemical industries, pharmaceuticals and more [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Moreover, when it is combined with other units, such as heating, ventilation, and air conditioning (HVAC) units in building systems, pre-air dehumidification could achieve cooling energy saving [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Similarly, it could be a potential energy-saving technology in wood drying processes [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Wood drying is an energy-demanding process that requires heat to warm up the air which circulates through a stack of lumber to remove its moisture [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. After absorbing the moisture, the air in dry kilns is saturated and should be vented as exhaust. Fresh and cold air is introduced to the kiln; however, it once again needs extra energy to be heated [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In contrast, if applying an air dehumidification membrane system to the dry kiln, it could remove the moisture from saturated air without any phase change, thereby allowing the warm air to be recycled into the system, retaining heat. The dehumidified air, which is still at a high temperature, can return to the drying system to run another cycle of drying [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMany polymer-based membrane materials, such as polydimethylsiloxane (PDMS), Polyether-block-amide (PEBAX), and Sulfonated poly(ether ether ketone) (SPEEK), can be used to make a dense membrane for air dehumidification[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] Among these materials, PDMS is commercially used in IMAD systems because of its low cost, chemical stability, nontoxicity, and good processability. When it is fabricated as a hollow-fiber form, PDMS tubular membranes have a high ratio of surface area to volume and are ease of scale-up[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] However, most polymeric materials, including PDMS, are avoided in the working environment with a temperature greater than 50\u0026deg;C. For instance, in the study of flue gas dehydration using PEBAX\u0026reg;1074 and sulfonated SPEEK membrane materials, field tests were carried out when the temperature of flue gas was cooled below 50\u0026deg;C [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In another study, feed gas streams are cooled solely to accommodate a membrane gas separation process, and then they are heated back up [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Reducing the gas temperature and then heating it up add extra cost and energy to the process [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn most softwood drying processes, the temperature of the air increases up to about 82\u0026deg;C [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Therefore, when testing the suitability of membranes for dehumidifying the exhaust air, it is important to address the influence of temperature on membrane\u0026rsquo;s performance (permeability and selectivity) instead of solely focusing on thermal stability/degradation analysis [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The performance of polymeric membrane materials can be improved by adding nanomaterials [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], ZnO [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], TiO\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], SiO\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], titanate nanotubes (TNTs) [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], Zeolite [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] and more. However, most of these nanoparticles are non-sustainable and in some cases are petroleum based.\u003c/p\u003e \u003cp\u003eCellulose nanocrystal (CNC), a class of nanomaterials with dimensions of 100\u0026ndash;300 nm long and 5\u0026ndash;70 nm in diameter derived from sustainable and renewable lignocellulosic biomass, can solve environmental problems related to other inorganic nanoparticles by serving as nature's storage for carbon dioxide. It has many attractive features, such as large specific surface area, high tensile strength and stiffness, abundance of surface hydroxyl groups, extremely low coefficient of thermal expansion (CTE), and more [\u003cspan additionalcitationids=\"CR21 CR22\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. So, it has been used to substitute for inorganic nanoparticles (such as TiO\u003csub\u003e2\u003c/sub\u003e, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) in film-type composites as reinforcement fillers to improve the strength, thermal expansion stability, optical property, etc. of the composites [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhen the solution-diffusion mechanism governs gas diffusion in the dense polymeric membranes, the gas molecules dissolve into a membrane, diffuse across the membrane thickness, and then desorb from the other side of the membrane [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This study aimed to develop a high-performance hybrid composite membrane for air dehumidification at elevated temperatures for wood drying applications. CNC was chosen as an additive to PDMS because of two hypotheses: 1) the surface hydroxyl groups of CNC could increase the moisture adsorption sites in the PDMS membrane to improve the solubility of water vapor on the membrane surface and create a large water vapor concentration difference for a fast diffusion and 2) CNC's low thermal expansion attribute could restrain the PDMS thermal expansion at elevated temperatures if CNCs disperse in PDMS uniformly.\u003c/p\u003e \u003cp\u003eTo achieve the goal, four objectives of this study were to 1) synthesize CNC/PDMS membranes using CNC suspension with four concentrations (0%, 2%, 4%, and 6%); 2) measure the water vapor permeability, nitrogen gas permeability, their selectivity, and coefficient of thermal expansion of the membrane samples at three different temperatures (25\u0026deg;C, 50\u0026deg;C, and 80\u0026deg;C); 3) characterize the morphology of the membrane samples, and 4) determine the optimal CNC concentration for making a high-performance CNC/PDMS composite membrane.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003ePDMS prepolymer and curing agent kits (Dow SYLGARDTM 184 Silicone Elastomer kit) were purchased from Dow Inc. (MI, USA). A CNC suspension at 11.8% solids was purchased from the USDA Forest Products Laboratory, distributed by the Process Development Center of the University of Maine (ME, USA). CNCs were subjected to comprehensive characterization in a previous study [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The results of the study revealed that the CNC particles had an average length of 134\u0026thinsp;\u0026plusmn;\u0026thinsp;52 nm and a width of 7\u0026thinsp;\u0026plusmn;\u0026thinsp;2 nm. The aspect ratio of the particles was determined to be 19. Additionally, the study reported a sulfate half-ester (-OSO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) content of 335 mmol kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the CNCs.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Methods\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Synthesis of membranes\u003c/h2\u003e \u003cp\u003eThe PDMS prepolymer and curing agent at the ratio of 10:1 by weight (e.g., 10 grams of PDMS prepolymer and 1 gram of curing agent) was mixed mechanically for 5 minutes at room temperature. The solution was degassed for 45 seconds with a planetary centrifugal bubble free mixer (THINKY ARE-310, Tokyo, Japan). Then the solution was cast on a Teflon plate using a casting knife. The wet film had a nominal thickness of 150 \u0026micro;m. The wet film was cured in an oven at 50\u0026deg;C for 24 h. The pure PDMS was used as control group (i.e., 0% CNC).\u003c/p\u003e \u003cp\u003eFor making CNC/PDMS membranes, ten (10) grams of the PDMS prepolymer and 1 gram of the curing agent were mixed mechanically for 5 minutes at room temperature. Appropriate amount of CNC suspension was added to the 11-gram solutions to achieve the CNC solid concentrations of 2%, 4%, and 6% in total solids, respectively. The mixture was then mechanically mixed for 1 hour, degassed for 45 seconds, and cast on a Teflon plate using a casting knife to obtain a wet membrane with a nominal thickness of 130 and 150 \u0026micro;m for Pure PDMS and CNC/PDMS films, respectively [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. The wet membranes were first dried at room temperature in a vacuum desiccator with a vacuum pressure of 88 kPa for 1 hour, intended to remove any remaining air bubbles in the wet membranes. After that, the semi-cured membranes were transferred to an oven and cured at 50\u0026deg;C for 24 h [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe thickness of dry film samples was measured using a digital micrometer (Mitutoyo, IL, USA) with an accuracy of 0.001 mm. Multiple measurements were performed to determine the average thickness of the film samples.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Scanning electron microscopic (SEM) analysis\u003c/h2\u003e \u003cp\u003eThe morphology of the CNC/PDMS membrane samples was observed using a scanning electron microscope (SEM) (NVision 40, Zeiss, Germany). The sample was placed on a specimen mount using carbon tape and then was coated with conductive silver. The regions of interest of the sample were sputter coated with gold (23 nm) using a Cressington 108 auto sputter coater (Ted Pella Inc., Redding, CA, USA). The images were taken at an accelerating voltage of 3 kV.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Atomic Force Microscopy (AFM) analysis\u003c/h2\u003e \u003cp\u003eThe PDMS and CNC/PDMS samples were cut into 5 mm x 5 mm areas for observation on an AFM (MFP-3D, Oxford Instruments Oxon, UK). Images were collected with an AC200TS-R3 probes with 9\u0026thinsp;\u0026plusmn;\u0026thinsp;6 (nN/nm) spring constants. Alternating current mode produced images with a set point of (0.4 V) and constant free air amplitude of (1 V).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.2.4 ATR-FTIR analysis\u003c/h2\u003e \u003cp\u003eThe ATR-FTIR analysis was performed using a PerkinElmer Spectrum Two\u0026trade; FTIR spectrometer (Shelton, CT, USA) to evaluate the nature of the interaction between the CNCs and PDMS in the membranes. Each sample was measured at a resolution of 4 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The data were obtained under an accumulation of 16 scans in the range of 450\u0026ndash;4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.2.5 Measurement of water vapor permeability of membranes\u003c/h2\u003e \u003cp\u003eThe water vapor transmission rate (WVTR) was measured using a dynamic vapor sorption (DVS) instrument (Model: DVS Advance; Surface Measurement Systems, London, UK) as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The sample was placed to seal a Payne cell. Silicone gel beads were placed in the cell to absorb water vapor that entered the cell to maintain a 0% RH in the headspace. The surrounding environment of the Payne cell was controlled by DVS to desired testing conditions. For each sample type, nine (9) replicates cut from three same membranes were tested. The thickness of each sample was measured using a digital micrometer. Each sample was tested at 25\u0026deg;C, 50\u0026deg;C, and 80\u0026deg;C and a constant RH of 60%. The increase of mass of the Payne cell assembly with time was recorded simultaneously. The tests followed the ASTM E96 Standard test method for water vapor transmission of materials (ASTM 2016). The H\u003csub\u003e2\u003c/sub\u003eO permeability (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eH2O\u003c/em\u003e\u003c/sub\u003e) was calculated using Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e):\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{P}_{{H}_{2}O}=\\frac{WVTR\\times\\:{T}_{mem}}{\\:{\\varDelta\\:}_{Vapor\\:pressure}}=\\frac{\\left(\\varDelta\\:m/\\varDelta\\:t\\right)\\times\\:{T}_{m}}{A\\times\\:\\varDelta\\:p\\times\\:18}\\:\\:\\left(\\frac{mol}{m\\bullet\\:s\\bullet\\:Pa}\\right)\\:$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eWhere, \u003cem\u003eΔm/Δt\u003c/em\u003e is the slope of a linear section of the mass versus time, g/s; \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e is the thickness of the sample membrane, m; \u003cem\u003eA\u003c/em\u003e is the open area of the Payne cell, 1.18^10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e m\u003csup\u003e2\u003c/sup\u003e; \u003cem\u003eΔp\u003c/em\u003e is the partial pressure difference of water vapor, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:p=\\frac{\\varDelta\\:RH}{100}\\times\\:Saturated\\:water\\:pressure\\)\u003c/span\u003e\u003c/span\u003e at 25\u0026deg;C,50\u0026deg;C, and 80\u0026deg;C, Pa (Saturated water vapor pressure at 25\u0026deg;C\u0026thinsp;=\u0026thinsp;3171 Pa, 50\u0026deg;C\u0026thinsp;=\u0026thinsp;12351 Pa, 80\u0026deg;C\u0026thinsp;=\u0026thinsp;47415 Pa);18 g/mol is the molecular weight of H\u003csub\u003e2\u003c/sub\u003eO.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.2.6 Measurement of nitrogen gas permeability of membranes\u003c/h2\u003e \u003cp\u003eThe pure nitrogen gas transmission rate (NGTR) was measured using a single gas transmission cell (Custom Scientific Instruments Inc, PA, USA) as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, following the ASTM D1423-82(2015) Standard test method for determining gas permeability characteristics of plastic film and sheeting (ASTM 2015). Samples were cut into circles with a diameter of 0.12 meter thickness was recorded. One sample was mounted to separate the cell into the upper and lower chambers. Compressed nitrogen gas flowed into the lower chamber, diffused through the sample, and entered the upper chamber. The volume expansion of the upper chamber was measured by recording the movement of a liquid color slug in the capillary tube. Nine (9) replicates for each sample type were tested. The transmission cell was placed in a water bath to maintain the desired temperatures of 25\u0026deg;C, 50\u0026deg;C, and 80\u0026deg;C. The pressure difference between the lower chamber and upper chamber was measured by a pressure gauge. The N\u003csub\u003e2\u003c/sub\u003e gas permeability was calculated using Eq.\u0026nbsp;(\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e):\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:{P}_{{N}_{2}}=\\frac{NGTR\\times\\:{T}_{m}}{\\varDelta\\:p}=\\:\\frac{{P}_{0}\\:\\times\\:\\:S\\times\\:\\pi\\:{D}^{2}\\times\\:{T}_{m}}{\\varDelta\\:p\\times\\:4\\:A\\:R\\:T}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(\\frac{mol}{m\\bullet\\:s\\bullet\\:Pa}\\right)\\:$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eWhere \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e is the ambient pressure, 101325 Pa, \u003cem\u003eS\u003c/em\u003e is the rate of rising of the capillary slug (m/s); \u003cem\u003eD\u003c/em\u003e is the capillary tube\u0026rsquo;s inner diameter, 0.4957^10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e m; \u003cem\u003eA\u003c/em\u003e is the open area of the cell, 0.6655^10\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e m\u003csup\u003e2\u003c/sup\u003e; \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e is the thickness of the sample membrane, m; \u003cem\u003eΔp\u003c/em\u003e is the pressure difference between the lower and upper chamber, i.e., gauge pressure, Pa; \u003cem\u003eT\u003c/em\u003e is the temperature of gas, K; R is the gas constant (8.3143 m\u003csup\u003e3\u003c/sup\u003e.Pa/(mol.K)).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.2.7 Calculation of Selectivity of water vapor and nitrogen\u003c/h2\u003e \u003cp\u003eThe selectivity (α) was obtained from the ratio of H\u003csub\u003e2\u003c/sub\u003eO to N\u003csub\u003e2\u003c/sub\u003e permeability, Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\:\\alpha\\:=\\:\\frac{{P}_{{H}_{2}O}}{{P}_{{N}_{2}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.2.8 Measurement of coefficient of thermal expansion (CTE)\u003c/h2\u003e \u003cp\u003eThe in-plane coefficient of thermal expansion (CTE) of the PDMS and CNC/PDMS membrane samples were measured using a thermomechanical instrument (Q400 TMA, TA Instrument). Samples were cut into 5 mm \u0026times; 5 mm areas and one sample at a time was sandwiched between two crystal wafers to ensure force dispersion. An expansion probe rested on the surface of the samples with a 0.02 N preload. As the temperature was raised from 25\u0026deg;C to 100\u0026deg;C a heating rate of 5\u0026deg;C/min, the change in thickness of the sample was recorded, allowing the calculation of CTE from the slope of the resulting expansion temperature plots. CTE is calculated using Eq.\u0026nbsp;\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e4\u003c/span\u003e [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$$\\:CTE=\\:\\frac{\\varDelta\\:L}{{L}_{0}\\:\\times\\:\\:\\varDelta\\:t}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere L\u003csub\u003e0\u003c/sub\u003e is the initial length of the sample (\u0026micro;m); Δt is the temperature change (\u0026deg; C), and ΔL is the thermal expansion (or contraction) of the sample after the temperature change.\u003c/p\u003e \u003cp\u003eFor each concentration, 3 samples were prepared and tested, where performed in triplicate. Therefore, the average of Nine (9) replicates for each sample type were measured and reported.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e2.2.9 Statistical \u003cem\u003eanalysis\u003c/em\u003e\u003c/h2\u003e \u003cp\u003eTwo-way analysis of variance (ANOVA) was performed for two independent variables (CNC concentration and temperature) to understand the main effects and interaction effects of them on the water vapor and nitrogen gas permeability, and selectivity of the membrane samples. One-way ANOVA was conducted for the effect of the independent variable (CNC concentration) on CTE. All statistical analyses were run in OriginPro software version 2022b, with a level of significance of 0.05 [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Appearance and morphology of CNC/PDMS membrane samples\u003c/h2\u003e \u003cp\u003eThe appearance of four types of membrane samples is provided in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The Pure PDMS has the highest transparency, and the transparency of the film is decreased with increasing the CNC concentration. The SEM images (Fig.\u0026nbsp;4) show the top surface morphology of four membrane samples. The dispersion of CNC in PDMS is dependent on the concentration of CNC added. CNC particles are relatively small and distributed randomly in PDMS when 2% of CNC was added. In contrast, when the concentration of CNC was increased to 4% and 6%, the CNC aggregation became more significantly distinctive. In addition, these SEM images show the PDMS and CNC/PDMS membranes are dense membranes, and no pores or defects are observed at this level of magnification. AFM images (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e) were used to estimate the 3D shape and dimensions of CNC nanoparticles agglomerations. Most of the CNC particles have a height in the range of 10 nm to 100 nm. The maximum height of agglomerated CNC particles could reach over 100 nm. More high peaks are observed with the increase in CNC concentration.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.2 ATR - FTIR analysis\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows the FTIR spectra of an air-dried CNC film (Control-1), pure PDMS sample (Control-2), and CNC/PDMS samples with CNC concentrations of 2%, 4%, and 6%. For Control-1 CNC film, a strong O-H stretching vibration at 3332 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and bending band of H-O-H bond at 1638cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are observed [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. For Control-2 PDMS membrane, the featured peaks of PDMS include 2960 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for CH\u003csub\u003e3\u003c/sub\u003e group vibration, 1257 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the symmetric deformation of the CH\u003csub\u003e3\u003c/sub\u003e group, 887 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Si-C vibration, and 790 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Si-O vibration [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. When low concentrations of CNCs were blended in PDMS, the spectra of CNC/PDMS samples show that peaks at 3332 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1638cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e almost disappeared but the peak at 1057 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e representing the stretching vibrations of C-O in CNC became slightly distinctive [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The results reveal that the addition of CNC from 2\u0026ndash;6% did not change the general spectra pattern of CNC/PDMS samples. Therefore, the performance of CNC/PDMS membrane is mainly governed by the PDMS.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Permeability of water vapor\u003c/h2\u003e \u003cp\u003eThe values of water vapor permeability (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003e) increased with the CNC concentration from 0% (pure PDMS) to 2% and then decreased. The mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD values of water vapor permeability at 25\u0026deg;C for Pure PDM, 2% CNC/PDMS, 4% CNC/PDMS, and 6% CNC/PDMS were 30,683.6\u0026thinsp;\u0026plusmn;\u0026thinsp;615.9, 38,295.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1,070.9, 35,883.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1,248.8, and 35,846.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1,338.3 Barrer, respectively. The addition of 2% CNC resulted in an increase of 24.8%, 30.9%, and 11.2% at 25\u0026deg;C, 50\u0026deg;C, and 80\u0026deg;C, respectively. Higher concentrations of CNC (4% and 6%) show a slightly decreasing trend for water vapor permeability, while the permeability values remained higher than those for pure PDMS membranes. This trend is the same in all three temperatures except for 80\u0026deg;C. When the temperature increased from 25\u0026deg;C to 80\u0026deg;C, the permeability of water vapor decreased dramatically.\u003c/p\u003e \u003cp\u003eTwo-way ANOVA results reveal that the effects of CNC concentration, temperature and their interaction on water permeability were statistically significant (Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003eA.1\u003c/span\u003e Supplementary document). Furthermore, the comparison between different CNC concentrations shows that the 2% CNC/PDMS is significantly different from other samples, but there is not any significant difference between pure PDMS (0% CNC), 4% CNC/PDMS, and 6% CNC/PDMS samples (Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003eA.2\u003c/span\u003e). Therefore, 2% CNC is the optimal concentration in terms of water vapor permeability.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Permeability of nitrogen gas\u003c/h2\u003e \u003cp\u003eThe values of Nitrogen gas permeability (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e) increased with the CNC concentration from 0% (pure PDMS) to 2% and then slightly decreased. The mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD values of Nitrogen gas permeability at 25\u0026deg;C for Pure PDM, 2% CNC/PDMS, 4% CNC/PDMS, and 6% CNC/PDMS were 263.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6, 324.9\u0026thinsp;\u0026plusmn;\u0026thinsp;18.7, 310.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4, and 310.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.3 Barrer, respectively.\u003c/p\u003e \u003cp\u003eThe nitrogen gas permeability (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e) was increased by 23.2%, 27.8%, and 16.0% at three temperatures when adding 2% CNC to the PDMS membrane. Similarly, higher concentrations of CNC (4% and 6%) show a slightly decreasing trend for nitrogen permeability compared with 2% CNC. The nitrogen permeability increased as the temperature was elevated from 25\u0026deg;C to 80\u0026deg;C.\u003c/p\u003e \u003cp\u003eTwo-way ANOVA results show the effect of CNC concentration on nitrogen permeability was not statistically significant but the effect of temperature on permeability was statistically significant (Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003eA.3\u003c/span\u003e). The interaction between temperature and concentration was not statistically significant either. Furthermore, the comparison between different CNC concentrations reveals that there was not a statistically significant difference between 2%, 4%, and 6% CNC/PDMS membranes but all the CNC/PDMS were significantly different from the Pure PDMS (Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003eA.4\u003c/span\u003e). Therefore, 2% CNC is the optimal concentration in terms of nitrogen gas permeability.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Selectivity of water vapor and nitrogen\u003c/h2\u003e \u003cp\u003eThe selectivity of water vapor over nitrogen (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003e) at 25\u0026deg;C of pure PDMS, 2%CNC/PDMS, 4%CNC/PDMS, and 6%CNC/PDMS were 116.3, 117.9, 115.7, and 115.5, respectively. A slight increase of about 3.1% was observed at 2% CNC addition, followed by a slight decrease when increasing the concentration of CNC at three temperatures. Two-way ANOVA results (Table \u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003eA.5\u003c/span\u003e) show that the effect of CNC concentration on selectivity was not statistically significant but the effect of temperature on selectivity was statistically significant. The interaction between temperature and concentration was not statistically significant for selectivity.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Coefficient of thermal expansion (CTE) of membranes\u003c/h2\u003e \u003cp\u003eThe dimensional stability of CNC/PDMS membranes influences how well the membrane operates at elevated temperatures. It was evaluated in terms of the coefficients of thermal expansion (CTE) of pure PDMS and CNC/PDMS membranes (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e10\u003c/span\u003e). The mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD of CTE for pure PDMS, from room temperature up to 100\u0026deg;C, was 301.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6 \u0026micro;m/m.\u0026deg;C. This measured value is in good agreement with the published values for CTE of PDMS which is 309 ppm/\u0026deg;C [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. After adding 2% CNC, the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD of CTE was reduced to 274.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5 \u0026micro;m/m.\u0026deg;C, which is about 12% lower than that of pure PDMS. This decrease in CTE was expected because CNC has a very low CTE of 9 \u0026micro;m/m.\u0026deg;C [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]and it helps to restrain the expansion of PDMS at elevated temperatures when CNCs are dispersed in PDMS [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. However, the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD of CTE of 4% CNC/PDMS and 6% CNC/PDMS was 269.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.2 and 264.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6, respectively. Increasing the CNC concentration to 4% and 6% did not further decrease the CTE greatly. One-way ANOVA results (Table \u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003eA.6\u003c/span\u003e) show that the decrease in the CTE between pure PDMS sample and 2% CNC/PDMS sample was statistically significant. Also, the comparison between different CNC concentrations (Table \u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003eA.7\u003c/span\u003e) shows that there is not a significant difference between 2%, 4% and 6% CNC/PDMS samples and all these samples are significantly different from Pure PDMS. Once again, 2% CNC is the optimal concentration in terms of CTE.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Influence of CNC agglomeration on membrane appearance and properties\u003c/h2\u003e \u003cp\u003eWhen CNC suspension was mechanically mixed with the PDMS prepolymer and curing agent solution and then dried until fully cured, CNC agglomeration occurred due to the poor compatibility of hydrophilic CNC and hydrophobic PDMS. When more agglomerated CNC particles were formed as the increase of CNC concentration, the membrane transparency decreased ascribed to the mismatch of refractive indexes between CNC and PDMS. Combined SEM and AFM images, the CNC particles are present on the membrane surface with needle-like shapes.\u003c/p\u003e \u003cp\u003eThe water vapor and nitrogen gas permeability, and CTE results of CNC/PDMS membrane samples show that 2% CNC was the optimal concentration. Increasing the CNC concentration were not further enhancing the membrane performance. The reason is also explained by the poor compatibility. The compatibility of CNC and PDMS might be improved by modifying the CNC, such as the silylation of CNC [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Effects of temperature on permeability of water vapor and nitrogen gas\u003c/h2\u003e \u003cp\u003eGas transport through dense polymeric membranes is governed by the solution-diffusion mechanism. Therefore, the effects of temperature on both solution and diffusion processes should be considered. The influence of temperature on solubility has been well addressed in terms of the van't Hoff relationship. Gas solubility correlates with its condensability. For less condensable gases (e.g., N\u003csub\u003e2\u003c/sub\u003e and O\u003csub\u003e2\u003c/sub\u003e) that often have lower critical temperatures (Table\u0026nbsp;1), gas solubility increases with an increase in the temperature. However, for condensable gases and vapors (e.g., water vapor) solubility decreases with increasing temperature [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The diffusion of gas molecules in a dense membrane is a thermally activated process and increases as the temperature increases, which is well described by the Arrhenius equation [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] However, for water vapor permeability, sorption is the preponderant factor [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], Which means the magnitude of solubility change is greater than that of diffusivity change (because of high condensability which correlates with the high critical temperature as shown in Table. 1), thereby resulting in a decrease in permeability. This explains why water vapor permeability decreases, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003e, when the temperature increases from 25\u0026deg;C to 80\u0026deg;C.\u003c/p\u003e \u003cp\u003eHowever, for the N\u003csub\u003e2\u003c/sub\u003e and O\u003csub\u003e2\u003c/sub\u003e molecules which are larger in kinetic diameter and less condensable, while increasing the temperature, there is increase in both the diffusivity and the solubility. This leads to an increase in permeability [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] This phenomenon is evident in the increased nitrogen gas permeability when the temperature rises from 25\u0026deg;C to 80\u0026deg;C, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Effectiveness of CNC as a nanofiller on water vapor and nitrogen gas permeability\u003c/h2\u003e \u003cp\u003eIn this study, a bio-based material CNC was used as a nano filler in the PDMS matrix to improve the PDMS membrane performance for air dehydration, to the best of our knowledge, which is the first time to report this type of application of CNC. CNC\u0026rsquo;s renewable and sustainable features make it possible as alternatives to non-renewable nanofillers, like zeolites (ZIF), silicon dioxide (SiO\u003csub\u003e2\u003c/sub\u003e), and titanate nanotubes (TNTs), reported in the previous studies [\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. While in most of the other studies regarding mixed matrix membranes, the nano filler they used in PDMS is not bio based and not renewable. The CNC used in this study is renewable and can be produced from sustainable sources, two features that make it superior to other nano particles such as zeolites (ZIF). On the other hand, to the best of our knowledge, this is the first time to make a mixed matrix membrane with PDMS for improving water vapor permeability of PDMS. Our study revealed that the water vapor permeability and nitrogen permeability of PDMS membrane at room temperature were found to be 3,683 Barrer and 263 Barrer, respectively, consistent with previous studies [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e], [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. After adding the optimal concentration of 2% CNC, the water vapor and nitrogen gas permeability at room temperature were increased by 24.8% and 23.5 %, respectively. I the study conducted by Mao et al. (2012), the addition of approximately 30 wt.% of ZIF-L to PDMS led to a significant 8.0% increase in water vapor permeability at 40\u0026deg;C [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Similarly, Sahin et al. (2020) conducted another study where they added 20 wt.% of ZIF-71 to PDMS and observed a significant enhancement of around 34% in the permeability of nitrogen gas at 35\u0026deg;C [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. CNCs have demonstrated several benefits in comparison to ZIF nanoparticles. For instance, they require a significantly lower weight ratio to achieve a similar improvement in water vapor and nitrogen gas permeability.\u003c/p\u003e \u003cp\u003eBeltran et al. reported an increase in the gas permeability of PDMS after adding modified SiO\u003csub\u003e2\u003c/sub\u003e, due to the increase in the free volume of the membrane [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Such an increase in free volume led to an increase in the diffusion coefficient. These findings suggested that PDMS, a rubbery polymer, may exhibit an increase in free volume upon the incorporation of nonporous fillers of SiO\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Li et al. (2010) found that adding TNTs into the PDMS matrix resulted in a significant enlargement of the fractional free volume (FFV)[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The enlargement of the FFV created more diffusion paths for small penetrants, and consequently, increased the gas permeability of the nanocomposite membranes. In this study, the effectiveness of CNC on the enhancement of water vapor and nitrogen gas permeability could be also explained by the modified FFV.\u003c/p\u003e \u003c/div\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eIn this study, CNC/PDMS membranes with the CNC weight concentrations of 0%, 2%, 4%, and 6% were successfully synthesized. The samples were defect-free and contained no observable pores under microscopic imaging because of the degassing step during preparation. The SEM images and AFM results revealed the CNC nanoparticles were dispersed in the PDMS matrix either randomly or in small agglomerations depending on CNC concentrations. The FTIR spectra confirmed the existence of CNCs in the CNC/PDMS samples. The addition of CNC alters the permeability and selectivity of the membranes. The optimal CNC concentration was 2% with enhanced water vapor permeability at all temperatures up to 24.8% while increasing the selectivity slightly up to 3.1%. In addition, the 2% CNC/PDMS samples showed an 8.9% lower value for CTE which results in higher thermal dimensional stability of the sample. The future work would be the modification of CNCs, e.g., silylation, to increase the compatibility between CNCs and PDMS polymer and increase the dispersion of CNCs in the PDMS matrix.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement:\u0026nbsp;\u003c/strong\u003eThis project was supported by the USDA National Institute of Food and Agriculture, McIntire-Stennis (Project number ME0-42205) through the Maine Agricultural \u0026amp; Forest Experiment Station; the U.S. Department of Agriculture\u0026rsquo;s Agricultural Research Service (USDA ARS Agreement No. 58-0204-6-003 \u0026amp; No. 58-0204-9-166); the US Forest Service and US Endowment for Forestry and Communities-P3Nano Advancing Commercialization of Cellulose Nanomaterials (Agreement 21-00166).\u003c/p\u003e\n\u003cp\u003eIn addition, authors would like to thank Dr. Elliot Sanders for help with the AFM testing and iLab UMaine for help to prepare SEM images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis project was supported by the USDA National Institute of Food and Agriculture, McIntire-Stennis (Project number ME0-42205) through the Maine Agricultural \u0026amp; Forest Experiment Station; the U.S. Department of Agriculture\u0026rsquo;s Agricultural Research Service (USDA ARS Agreement No. 58-0204-6-003 \u0026amp; No. 58-0204-9-166); the US Forest Service and US Endowment for Forestry and Communities-P3Nano Advancing Commercialization of Cellulose Nanomaterials (Agreement 21-00166).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest/Competing interests\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis work has no conflicts of interest to disclose.\u003cbr\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. This study did not involve human or animal subjects.\u003cbr\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the images and tables presented in this work are original results. Content adopted from other works has been cited carefully.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e \u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll research data is included in the article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthorship Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNasim Alikhani:\u0026nbsp;Methodology, Running tests, Visualization, Writing original draft.\u003c/p\u003e\n\u003cp\u003eLing Li: resources, writing \u0026ndash; review and editing, and funding acquisition.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eJinwu Wang: resources, writing \u0026ndash; review and editing, and funding acquisition.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eS. 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In this study a casting method was used to fabricate CNC/PDMS membranes. The water vapor permeability of the membrane samples was measured with a Payne diffusion cell (dry cup method) coupled with a Dynamic Vapor Sorption (DVS) instrument, while the nitrogen gas permeability was measured with a gas permeation cell. The results showed that the optimal CNC concentration of 2%, enhanced water vapor permeability at all temperatures up to 24.8% while increasing the selectivity slightly up to 3.1%. The membranes were characterized using AFM, FTIR, SEM, and TMA. measured the CTE of the prepared samples to study the dimensional stability as a function of temperature change. The optimized membranes showed an 8.9% lower value for CTE which results in higher thermal dimensional stability of the sample. The results have demonstrated that CNC-reinforced PDMS has potential to be used as selective membranes to remove water vapor from exhaust warm air such that the air recovers its drying capability and can be recirculated as the working medium in drying systems.\u003c/p\u003e","manuscriptTitle":"Cellulose Nanocrystal/Polydimethylsiloxane hybrid membranes for air dehydration at elevated temperatures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-30 17:04:31","doi":"10.21203/rs.3.rs-4716356/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-10-11T17:26:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-10-11T17:23:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-09-24T09:34:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Cellulose","date":"2024-07-10T07:36:26+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":"1503ccad-e3cd-4367-a958-7b9c9b34fa21","owner":[],"postedDate":"October 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-08-25T16:37:43+00:00","versionOfRecord":{"articleIdentity":"rs-4716356","link":"https://doi.org/10.1007/s10570-025-06707-4","journal":{"identity":"cellulose","isVorOnly":false,"title":"Cellulose"},"publishedOn":"2025-08-20 16:29:43","publishedOnDateReadable":"August 20th, 2025"},"versionCreatedAt":"2024-10-30 17:04:31","video":"","vorDoi":"10.1007/s10570-025-06707-4","vorDoiUrl":"https://doi.org/10.1007/s10570-025-06707-4","workflowStages":[]},"version":"v1","identity":"rs-4716356","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4716356","identity":"rs-4716356","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}