Environmentally Friendly Shape Memory Smart Composite Material with Multiple Response Modes

Environmentally Friendly Shape Memory Smart Composite Material with Multiple Response Modes | 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 Environmentally Friendly Shape Memory Smart Composite Material with Multiple Response Modes Fang Suo, Zhongyang Bai, Xiangwei Ma, Yongtao Yao, Yanju Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5034691/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Apr, 2025 Read the published version in Wood Science and Technology → Version 1 posted 11 You are reading this latest preprint version Abstract Cellulose and lignin offer advantages of low cost and environmental friendliness. In this study, a multi-responsive shape memory smart composite material was proposed based on carboxymethyl cellulose and lignin. Lignin imparts photothermal responsiveness to the composite, while cellulose provides water responsiveness. A bio-inspired structure that mimicking the water transport mechanism of plant leaves was developed to improve the water responsive functionalities of composite material (shape recovery within 30 seconds). A self-driven device that mimics the blooming of a flower was successfully fabricated using this composite material. The shape memory smart composite material exhibits a high degree of design flexibility. Based on the mechanisms of water response, a simple structure programming method was proposed, enabling the design of programmable structures with smart and controllable features. This study provides a new approach to the design of multifunctional smart materials, enhancing the application potential of shape memory materials under multiple environmental factors. Carboxymethyl Cellulose Lignin Water response Shape memory polymer Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1 Introduction Soft robots are a class of robots primarily composed of flexible materials, capable of interacting with environmental factors and exhibiting corresponding responsive behaviors. Soft robots can be composed of structures driven by flexible joints actuating rigid materials, or they can be entirely manufactured from flexible materials. Soft robots made from flexible materials are not constrained by the physical space limitations of their working environment, allowing for arbitrary changes in shape and structure to accomplish their task objectives[ 1 , 2 ]. The advancement of disciplines such as bionics, materials science, and mechanics has led to the extensive application of soft robots and flexible actuation systems in fields including biomedical engineering, civil infrastructure, environmental exploration, and aerospace. As the demand for such devices increases, soft robots must evolve to meet various application requirements. Developing multifunctional, multi-purpose soft robots with enhanced adaptability to complex environments has become a current challenge. Smart materials serve as the driving core of soft robots, responsible for converting external environmental energy into kinetic or other forms of energy, enabling complex shape changes or functional expressions. Due to the driving action of intelligent materials, soft robots can exhibit functionalities such as positional changes, object manipulation, and shape modulation under external environmental stimuli[ 3 , 4 ]. With the advancement of intelligent material technology, including the emergence of novel intelligent materials such as smart responsive hydrogels[ 5 ], shape memory polymers[ 6 ], and shape memory alloys[ 7 ], the diversity of driving mechanisms and response conditions for soft robots has increased. The response mode of the driving mechanism is crucial for energy conversion in soft robots, and it can determine their application environment and functional selection. Currently, the majority of driving modes include thermal[ 8 ], optical[ 9 ], humidity[ 10 ], and magnetic driving[ 11 , 12 ]. For current research and applications, designing multifunctional smart materials can maximize the potential of soft robots. Smart composite materials designed with various responsive materials can offer multifunctional advantages, thereby enhancing their application value. Additionally, these smart composites should also possess environmentally friendly and biodegradable properties to broaden their range of applications. Cellulose is a kind of forestry product extracted from wood with environmentally friendly characteristics[ 13 , 14 ]. Carboxymethyl cellulose (CMC) molecules contain a large number of carboxyl and hydroxyl groups, exhibiting excellent hydrophilicity and water absorption properties[ 15 , 16 ]. Thus, it can serve as a viable option for hydrophilic shape memory material raw materials. Additionally, it boasts advantages of low cost and good biodegradability[ 17 ]. Lignin is a complex polymer extracted from wood cell walls also with environmentally friendly characteristics[ 18 ]. Lignin molecules contain numerous conjugated functional groups, showcasing excellent photo-thermal performance and thus can serve as filler for photo-response functionalities. Lignin possesses characteristics such as high yield, environmental friendliness, and significant potential for application[ 19 ]. Polycaprolactone (PCL) is a widely used polymer in the field of biomedicine, characterized by excellent biocompatibility, often employed in medical device packaging and medical equipment manufacturing. Furthermore, due to its low melting point, PCL exhibits temperature-sensitive characteristic which makes it suitable as a switch for thermal response driving modes[ 20 , 21 ]. Thermoplastic polyurethane (TPU) is a commonly used elastomeric material at present, applicable in aerospace, medical devices, 3D printing, among other fields. TPU demonstrates good thermal stability and stable mechanical properties. As TPU is an amorphous polymer that lack of crystalline structure, it possesses higher toughness and elongation compared to commonly used materials such as PE, PP, and PVC, rendering it more suitable as a framework material for shape memory smart composite[ 22 , 23 ]. As shown in Fig. 1 , this study presents the design of a shape memory smart composite device for operation in wet and aquatic environments, featuring water, light, and thermal response modes. Inspired by capillary phenomena in plant leaf veins and transpiration, a CMC water transport network (CWTN) was fabricated using CMC as the raw material. This network possesses a structure characterized by loose porosity, allowing rapid absorption of moisture in humid environments and subsequent release in dry conditions, thereby achieving water-responsive functionality. In contrast to traditional water-responsive driving materials relying on hydrophilic functional groups such as polyvinyl alcohol and polyethylene glycol, the CWTN exhibits abundant hydrophilic functional groups at the microscopic level, endowing the material with hydrophilicity. Moreover, the physical effects generated at the macroscopic level facilitate accelerated water transport, potentially enhancing the responsiveness of water-responsive driving devices. Shape memory polymer (SMP) exhibits structural stability under normal conditions. Utilizing TPU, PCL, and lignin, SMP with dual light and thermal response functionalities were manufactured. These materials demonstrate excellent light and thermal response shape memory behavior. By integrating SMP with the CWTN, a smart composite with three response modes was fabricated. Finally, an environmentally friendly self-driven device with three response modes was successfully developed using this material design. 2 Experiment 2.1 Materials CMC was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd. Ferric chloride was obtained from Tianjin Hengxing Chemical Preparation Co., Ltd. Citric acid (CA) was acquired from Tianjin Dongli District Tianda Chemical Reagent Factory. TPU (1185A) was procured from BASF, Germany, and PCL (CapaTM 6800) was sourced from Perstorp, Sweden. Lignin, with a molecular weight of 3000–5000 g/mol, was purchased from Lingyu Chemical Co., Ltd. (China). Dimethylformamide (DMF) was obtained from Tianjin Yongda Chemical Reagent Co., Ltd. The polytetrafluoroethylene (PTFE) film was purchased from Dongguan Youka Plastic Co., Ltd. 2.2 Methods 2.2.1 Preparation of CWTN films Add 3g of CMC to a beaker containing 100ml of deionized water, and stir the mixture using a magnetic stirrer in a water bath at 80°C for 2 hours until the CMC is completely dissolved. Dissolve 2.7g of ferric chloride and 1.05g of CA in a beaker containing 100ml of deionized water to prepare the ferric ion/CA cross-linking agent (Fe/CA). Ultrasonicate the prepared CMC solution for 30 minutes to remove air bubbles, then pour it into a silicone mold with dimensions of 50mm in length, 50mm in width, and 5mm in depth. Place the mold in an electric blast drying oven (Shanghai Yiheng Scientific Instrument Co., Ltd) and dry at 80°C for 40 minutes. After drying, cool the mold containing the CMC gel to room temperature and pour in the Fe/CA cross-linking agent, allowing it to stand for 1 hour. Remove the cross-linked film from the mold and place it in a freeze dryer (Ningbo Xinzhi Biotechnology Co., Ltd) to dry thoroughly for 24 hours to obtain the CWTN film. 2.2.2 Preparation of T-P-L composite material and 3D printing filament Based on our previous research, the optimal ratio of the composite material was selected. TPU, PCL, and lignin were dried for one day and then uniformly mixed in a ratio of 12:8:5. The mixture was fed into a twin-screw extruder (SJSH-30, Nanjing Rubber and Plastics Machinery Plant Co., Ltd., China) for thorough mixing to obtain the T-P-L composite material. The extruder temperatures were set at 160°C, 175°C, 180°C, 185°C, 180°C, and 175°C. The T-P-L composite material was then fed into a crusher (SMP-200, Zhangjiagang Songben Plastic Machinery Co., Ltd., Zhangjiagang, China) to obtain composite material pellets. The composite material pellets were fed into a single-screw extruder filament machine (SHSJ25, Dongguan Songhu Plastic Machinery Co., Ltd, China). The temperature zones were set at 175°C, 185°C, and 150°C. The screw speed was set at 30 rpm, and the traction speed was controlled within the range of 10 rpm to 15 rpm to maintain a filament diameter of 1.75 ± 0.1 mm. The filament was collected using a spool for future use. A commercial 3D printer (Changsha Fuzhi Technology Co., Ltd) was used for 3D printing, with the printing parameters provided in Table S1 . 2.2.3 Preparation of shape memory smart composite films Place the CWTN film and the printed film-like structure separately on two iron plates covered with polytetrafluoroethylene (PTFE) film. Using a dropper, apply a certain amount of dimethylformamide solution onto the CWTN film. Once the CWTN film has fully absorbed the dimethylformamide solution, press the 3D-printed film onto the CWTN film to bond the two layers together. Then, fully dry the bilayer film structure at 40°C to remove the dimethylformamide solution, resulting in a shape memory smart composite film with a bilayer film structure. 2.3 Characterization Methods 2.3.1 Water absorption rate of CWTN films Measure the initial weight of the CWTN film using an electronic balance. Hold one end of the CWTN film with tweezers and immerse the other end in water dyed red with ink. Observe the height of the water rise every 1 minute and measure the weight of the film in this state. 2.3.2 Fourier transform infrared spectroscopy (FTIR) To investigate the promoting effect of internal polymer functional groups on water molecule absorption, Fourier Transform Infrared Spectroscopy (FTIR) (Shimadzu, Japan) was used to test CMC, CA, and CWTN films at room temperature. The testing range was from 500 cm⁻¹ to 4000 cm⁻¹. 2.3.3 Morphological observation The morphology of the CWTN films was observed using a polarizing microscope (MODEL BXSSMTRF-S, Olympus Corporation, Japan). The shape memory smart composite film was gold-sputtered and observed using a scanning electron microscope (SEM; Apreo S HiVac, Thermo Scientific, USA) at a voltage of 20 kV to observe the morphology of both surfaces and the interface of the middle layer of the shape memory smart composite films. 2.3.4 Hydrophilic-hydrophobic effect testing of shape memory smart composite films The static contact angle was measured at room temperature using a fully automated video contact angle measurement instrument (OCA20, DataPhysics Instruments, Germany). The test liquid used was water. 2.3.5 Mechanical properties The tensile properties of the composite films were tested using a universal testing machine (CMT5504, MTS Systems China Co., Ltd., China) at a testing speed of 10 mm/s. With the CWTN film thickness fixed at 0.4mm, T-P-L films of varying thicknesses (0.2mm, 0.3mm, 0.4mm, 0.5mm, and 0.6mm) were selected to create samples. These samples were cut into rectangular shapes measuring 50mm in length and 10mm in width for mechanical property measurements. 2.3.6 Optical properties and photothermal energy conversion performance The optical absorption properties of both surfaces of the composite films were tested using an ultraviolet-visible spectrophotometer (CARY100; Agilent Technologies Inc., USA). The testing range was from 200 nm to 800 nm, and the test samples were prepared as 20 mm diameter discs. The photothermal energy conversion performance of both surfaces of the composite films was tested using a xenon lamp light source system (CEL-HXF300, Beijing China Education Au-light Co., Ltd., China). A light power meter (CEL-FZ-A; Beijing China Education Au-light Co., Ltd., China) was used to adjust the light intensity to 200 mW/cm². An infrared camera (T1, Zhejiang Dali Technology Co., Ltd., Zhejiang, China) was used to observe the temperature increase of both surfaces of the composite films under illumination. Temperature measurements were recorded by every 5 seconds. 2.3.7 Thermal responsive shape memory performance Cut the composite film into rectangular specimens with dimensions of 30 mm in length and 15 mm in width. Place the specimens in an electric blast drying oven and heat to 60°C. Once the specimens have softened, bend them into a U-shape and fix them in this position. Cool the specimens to room temperature and record the bending angle, which is the shape fixation angle. Then, place the specimens back into the blast drying oven and allow them to complete the shape recovery process. Remove the specimens and cool them to room temperature. Record the angle of the specimens at this point as the shape recovery angle. Calculate the shape fixation rate (R f ) and shape recovery rate ( R r ) of the shape memory smart composite films using the following formulas: Where θ₀ is the initial angle, θ is the shape fixation angle, and θ' is the shape recovery angle. 2.3.8 Light responsive shape memory performance Place rectangular specimens with dimensions of 30 mm in length and 15 mm in width into an electric blast drying oven set at 60°C. Once the specimens have softened, bend them into a U-shape. Fix the specimens and cool them to room temperature, then measure the bending angle, which is the shape fixation angle. Place the U-shaped specimens on a horizontal plane with the U-connection facing upwards. Use a xenon lamp light source system to irradiate the U-shaped specimens from top to bottom, and record the light-responsive shape recovery process using a digital camera. Use Photoshop (Adobe Systems Software Ireland Ltd., USA) software on a computer to calculate the shape recovery angle at 10-second intervals. The formulas for calculating the shape fixation rate and shape recovery rate are given by equations ( 1.1 ) and ( 1.2 ). 2.3.9 Water responsive shape memory performance Soak the rectangular specimens in deionized water for 30 minutes. Then, remove the specimens and allow them to air dry, during which the specimens will bend. Measure the bending angle of the specimens as shape fixation rate at 1-minute intervals for a total duration of 5 minutes. Subsequently, immerse the specimens in water and use a digital camera to record the water-responsive shape recovery process. Use Photoshop software to measure the shape recovery angle of the specimens on a computer at 5-second intervals. The formulas for calculating the shape fixation rate and shape recovery rate are given by equations ( 1.1 ) and ( 1.2 ). 3. Results and Discussion 3.1 Response characteristics of shape memory smart composite material films The shape memory smart composite films with water-responsive functionality require a module that responds to water. Inspired by the principles of water transport and transpiration in plant leaves, designed and fabricated the CWTN water-responsive module, which possesses both water transport and water dispersal capabilities. This module is made using CMC, a material rich in hydrophilic functional groups[ 24 ]. Figure 2 a illustrates the water absorption effect of the CWTN water-responsive module, where water is transported upward from the bottom of the CWTN film, overcoming gravity. In just 4 minutes, the weight of the CWTN film increases by 600%, demonstrating that the water-responsive module exhibits excellent hydrophilicity and a rapid response rate to water transport. To further analyze the water-responsive mechanism of the CWTN water-responsive module, we investigated the hydrophilic mechanism of CWTN from both macroscopic and microscopic perspectives. Figure 2 b presents the FTIR spectra of CWTN and CMC. The spectrum of CMC shows distinct characteristic peaks of COO- at 1416 cm − 1 and 1592 cm − 1 . Additionally, a broad peak for -OH appears between 3000 cm − 1 and 3650 cm − 1 . These hydrophilic functional groups are crucial for the hydrophilicity of CMC[ 25 ]. The spectrum of CWTN exhibits the characteristic peaks of COO- at 1416 cm − 1 and 1592 cm − 1 . Due to the presence of CA as the chelating agent add to the system, a vibration peak for carboxylic acid C = O appears at 1728 cm − 1 (Fig. S1 ). A broad peak for -OH is also observed between 3000 cm − 1 and 3650 cm − 1 . This indicates that CWTN retains most of the hydrophilic functional groups of CMC at the microscopic level, thus endowing the CWTN film with excellent hydrophilicity. This is a significant reason for the rapid water-responsive functionality of the CWTN film. Figure 2 c(Ⅰ) shows the surface imaging of CWTN observed using a microscope. It can be seen that CWTN exhibits a macroscopic crosslinked network structure with large pores. This phenomenon is due to the complexation reaction of Fe³⁺ with CMC and CA, resulting in the formation of a three-dimensional channel network cross-linked structure, the reaction mechanism was shown in Fig. S2. These structures are preserved during the freeze-drying process, resulting in formations similar to the vascular channels and stomata in plant leaves. Upon contact with water, surface tension facilitates the filling of these channels with water. The crosslinked porous structure ensures uniform contact between water and the CWTN surface, thereby increasing the contact area with water. The combined effect of numerous hydrophilic functional groups and the crosslinked porous structure endows the CWTN film with strong water-responsive functionality. Figure 2 c(Ⅱ) shows the SEM image of the interlayer connection in the bilayer film structure, observing that the two layers are tightly bonded together. This is due to the dissolution of the TPU and PCL on the surface layer of the T-P-L film by DMF, which increases the fluidity of the dissolved polymers, allowing them to penetrate into the surface layer of the CWTN film. This phenomenon is intensified under pressure. Upon drying, the polymers that have penetrated into the CWTN film precipitate due to the evaporation of the solvent and bond with the T-P-L composite film, resulting in the CWTN film and T-P-L film adhering to each other, thereby forming a stable bilayer film structure. To investigate the hydrophilic anisotropy of the shape memory smart composite films, studied the hydrophilic and hydrophobic properties of the CWTN layer and the T-P-L layer, respectively. Figure 2 c(Ⅲ) shows the CWTN surface as observed under a SEM. After the CWTN film was adhered to the T-P-L composite film, the crosslinked porous structure was still retained, giving one side of the composite film excellent hydrophilic properties. The static contact angle test results show that the water contact angle of the CWTN surface is only 19°. Figure 2 c(Ⅳ) shows the SEM imaging of the T-P-L composite surface. The surface exhibits protrusions caused by lignin agglomerating and exposing on the polymer surface. The static contact angle test results show that the water contact angle of the T-P-L composite surface reaches 80°, significantly different from the CWTN surface. This is because TPU and PCL are hydrophobic materials[ 26 , 27 ]. This result demonstrates that the shape memory smart composite film exhibits obvious hydrophilic anisotropy on its two sides. The T-P-L composite film has good stability in water environments, thus when the CWTN film absorbs water and expands or loses water and contracts, it provides the bending and recovery force for the composite film. This is the fundamental mechanism enabling the water-responsive mode of the shape memory smart composite film. The shape memory smart composite film exhibits different environmental response modes. According to our previous research, T-P-L is a composite material with excellent thermos-responsive and light-responsive shape memory properties, having a relatively low shape memory transition temperature (T tran ), at 53°C[ 28 ]. Consequently, the shape memory smart composite film also possesses corresponding thermos-responsive and light-responsive functionalities. Since heat acts on the film through conduction, the composite film exhibits shape memory properties similar to SMP with no anisotropic characteristics in response to heat. Here, we focus on investigating the light-responsive properties of the composite film. Figure 2 d shows the absorbance of both sides of the composite film. As illustrated, the T-P-L layer exhibits good absorption in both the ultraviolet and visible light ranges. This is due to the conjugated functional group structures within lignin that convert light energy into thermal energy[ 29 ]. Consistent with previous analysis, the T-P-L composite film surface has many exposed lignin agglomerates, resulting in excellent light absorption. The CWTN layer shows relatively low absorbance in the visible light range, indicating that the CWTN layer does not have significant light-responsive properties, and the response to light is uneven between the two sides of the composite film. Figure 2 e depicts the temperature increase on both sides of the composite film under xenon lamp illumination. The T-P-L layer demonstrates a good photothermal conversion effect, capable of converting light energy into heat energy within a short time, reaching the T tran in about 33 seconds. In contrast, the CWTN layer does not reach the transition temperature within 60 seconds. Therefore, it can be concluded that the photosensitive layer of the composite film is the T-P-L layer, which is significant for the structural design of self-actuating device. 3.2 Response modes of shape memory smart composite films As shown in Fig. 3 , the shape memory smart composite film has three independent responsive actuation modes to meet the demands of different usage environments: thermal responsive mode, light responsive mode, and water responsive mode. The shape memory smart composite film is composed of a CWTN water-responsive film and a T-P-L film made of shape memory polymers. The thermal and light responsive actuation modes rely on the shape memory effect of the T-P-L film. These two responsive actuation modes are similar to the shape memory effect of shape memory polymers. After the shape is programmed and fixed by external force, the material undergoes a shape recovery process. The water-responsive mode is achieved through the dry-shrink and wet-swell properties of the CWTN film, it is a commonly observed water response driving pattern[ 30 , 31 ]. This phenomenon occurs on only one side of the composite film, while the other side remains stable in the water environment. When the CWTN film loses water, one side of the composite film contracts, causing the composite film to bend. When the CWTN film reabsorbs water, the composite film returns to its original shape. This process can be entirely controlled by water, eliminating the traditional need for external force programming in responsive actuators. Figure 4 a and Fig. 4 b shows the thermal responsive actuation performance of the shape memory smart composite film. Since the thermal responsive actuation performance of the shape memory smart composite film originates from the thermal responsive shape memory performance of the T-P-L composite material, and CWTN itself does not have thermal responsive actuation capabilities. Therefore, when the T-P-L layer is relatively thin, the shape fixation ability of the composite film is poor. As the thickness of the T-P-L layer increases, the shape fixation rate increases. When the thickness of the T-P-L layer reaches 0.5 mm, the shape fixation rate exceeds 85%. The shape recovery ability of the shape memory smart composite films was shown in the relationship of recovery rate and thickness. It can be seen that regardless of the thickness of the T-P-L layer, the composite film exhibits excellent shape recovery ability, with shape recovery rates above 90%. During the actuation process of the composite film, the shape recovery ability of T-P-L is primarily utilized. The shape memory smart composite film demonstrates good thermal responsive actuation performance. Based on comprehensive comparison, when the T-P-L thickness reaches or exceeds 0.5 mm, the shape memory smart composite film exhibits optimal thermal responsive actuation performance. The water responsive actuation mode is driven by the CWTN water actuation module. Figure 3 c shows the relationship between the fixation rate of the composite film and time as the film is exposed to air and the water evaporates naturally. Due to the abundance of pore-like structures similar to plant leaf stomata on the surface of the CWTN film, water easily dissipates into the air. As the water dissipates, the pore structure within the CWTN layer contracts and undergoes volumetric shrinkage, leading to the bending of the composite film. The composite film can achieve 100% bending rate within four minutes. At this point, a certain amount of elastic potential energy is stored within the T-P-L layer, and the bending process stops once the stress between the T-P-L layer and the CWTN layer reaches equilibrium. As the thickness of the T-P-L layer increases, the bending speed slows down because the T-P-L layer gradually dominates the overall performance of the composite film. However, when the thickness of the T-P-L layer reaches 0.6 mm, the composite film can still complete the bending process within five minutes. Figure 3 d shows the relationship between the shape recovery rate of the composite film in water and time. It can be seen that the composite film has a very rapid water-driven shape recovery process. When the composite film is immersed in water, the water enters the internal structure along the pores on the surface of the CWTN layer, causing the pores within the CWTN layer to absorb water and expand. At this point, the T-P-L layer also releases the stored elastic potential energy, assisting the composite film in returning to its original shape. As the thickness of the T-P-L layer increases, the water-driven shape recovery ability of the composite film also increases. Therefore, it can be concluded that the water-responsive bending process of the composite film is determined by the CWTN layer, while the shape recovery process is the result of the combined action of both the CWTN layer and the T-P-L layer. Compared to previous studies, this shape memory material demonstrates a remarkably rapid water-responsive recovery process[ 32 – 34 ]. This can be attributed to the excellent hydrophilic properties of the CWTN, allowing the shape memory smart composite film to complete the water-responsive recovery process in almost 30 seconds. The light responsive actuation mode relies on the photothermal conversion ability of the T-P-L layer, so the light responsive actuation process of the composite film is similar to the light responsive shape recovery process of shape memory polymers. Figure 3 e shows the light responsive actuation process of the composite film. It can be seen that the thickness of the T-P-L layer is not related to the light responsive actuation performance. Previous studies have confirmed that the light responsive shape memory ability of T-P-L composites is related to the lignin content in the composite material[ 28 ]. Therefore, with the same proportion of lignin, all samples exhibit similar light responsive actuation performance. Additionally, the actuation process can be completed within 60 seconds, with a shape recovery rate of up to 88%. Consequently, the composite film demonstrates a rapid responsive light responsive actuation characteristic. Mechanical performance is fundamental to the operation of shape memory performance, as they must possess sufficient mechanical properties to maintain shape stability and operational stability during use. Figure 3 f shows the tensile strength of the composite films. Since ionic bonds are weak coordination types of chemical bonds, the CWTN film itself does not possess good mechanical properties[ 35 ]. Therefore, as the thickness of the T-P-L film increases, the tensile strength gradually increases. The composite film achieves the highest tensile strength when the T-P-L film thickness reaches 0.5 mm. When the thickness of the T-P-L film exceeds 0.5 mm, the tensile strength decreases. This is due to the fact that the raw material of the CWTN film is cellulose, whose internal molecular chains are arranged in a fibrous manner. During the adhesion process of the two films, the two materials wrap around each other at the contact surface. Previous studies have demonstrated that fibrous fillers can increase the mechanical properties of polymers to a certain extent, and proper proportion adjustment can achieve optimal mechanical performance[ 36 , 37 ]. Therefore, the samples with different ratios of CWTN to T-P-L exhibit varying mechanical properties. When the thickness of the T-P-L film exceeds 0.5 mm, the excessive polymer composite material begins to dominate the mechanical properties of the film, leading to a decrease in tensile strength. Therefore, the optimal mechanical performance is achieved with a CWTN film thickness of 0.4 mm and a T-P-L film thickness of 0.5 mm. After comprehensive consideration, the optimal ratio was determined to be a T-P-L layer thickness of 0.5 mm and a CWTN layer thickness of 0.4 mm. This ratio was then used to design and manufacture self-actuating device with three response modes. 3.3 Flexible self-actuating device with three actuation modes Shape memory smart composite films can be used to create self-actuating devices that respond to different environmental stimuli. By adjusting the structural distribution of the CWTN layer and the T-P-L layer, self-actuating devices can be designed to perform specific functions. In this study, a flexible self-actuating device with three actuation modes, thermal, light, and water, which was fabricated using shape memory smart composite films. As shown in Fig. 5 a, the structure of the T-P-L layer was designed and fabricated using a commercial 3D printer. A petal structure with five blades, with a diameter of 50 mm and a thickness of 0.5 mm, was printed using T-P-L composite filament. The CWTN film was cut into a petal structure similar to that of the printed T-P-L layer. The assembly scheme of the self-actuating device is shown in Fig. 5 b. Each petal is controlled by a shape memory smart composite film composed of two layers, mimicking the opening of a flower. Previous studies have demonstrated the poor photothermal energy conversion of the CWTN layer. To ensure that light irradiation from the CWTN layer side can still achieve light responsiveness, the petal ends of the CWTN layer were removed and adhered to the T-P-L layer, exposing a portion of the T-P-L film. The CWTN layer serves as the water-responsive sensing layer, while the exposed T-P-L layer acts as the light-responsive region. This design allows the petals of the self-actuating device to bend in the same direction under all three actuation modes, achieving consistent responsive behavior. As shown in Fig. 5 c, the self-actuating device successfully achieved three actuation modes. These three actuation modes operate independently. By heating the self-actuating device to T tran , the T-P-L layer softens, making the device easy to deform. Under the action of external force, each petal of the flower is fixed in an upright shape, mimicking an unbloomed bud. The bud shape serves as the initial shape for the thermal and light responsive actuation modes. When the device is reheated to Ttran, the petals soften and automatically display a blooming process due to the shape recovery performance of the T-P-L layer. Subsequently, the petals can be fixed in an upright shape and cooled, allowing the self-actuating device to return to its initial bud shape. The light responsive actuation mode is similar to the thermal responsive mode. A xenon lamp is used to vertically irradiate the self-actuating device in its bud shape. Each of the five petals has an exposed T-P-L layer that serves as the photosensitive area. These photosensitive areas convert light energy into thermal energy and conduct it to the petals. When the heat in the petals raises the temperature to Ttran, the flower opens. The device completes the process of mimicking flower blooming under the influence of light. Subsequently, external force is used to return the flower to its initial shape, and it is cooled and fixed to complete one actuation cycle. The cycle of the water responsive actuation mode can be entirely controlled by water. The self-actuating device is soaked in water for 30 minutes. Then, the device is placed in the air to dry naturally. Due to the evaporation of water, the device bends towards the CWTN layer side, ultimately reaching the initial shape of the water responsive mode. When the device is re-immersed in water, the CWTN layer absorbs water molecules and expands, causing the self-actuating device to complete the blooming process. Then, when the device is exposed to air again, the pores in the CWTN layer release water molecules into the air, causing the CWTN layer to contract. The already open flower reverts to a bud. The water responsive mode eliminates the need for external force to fix the shape, making it convenient to use in water environments. Finally, based on the characteristics of the water response model, a controllable programming strategy is proposed. As shown in Fig. S3, in this structure, CWTN is arranged on both sides of T-P-L. Specific CWTN modules can be activated at designated locations as needed to trigger their water responsive functions, allowing for predetermined shape changes. Moreover, all shape transformations in this structure can be repeatedly cycled without external force. The combination strategy of CWTN and T-P-L enables the development of various cyclic driving modes, providing a solution for expanding the application space of flexible actuators and enhancing environmental adaptability. 4. Conclusions In this study, a feasible method was developed for making environmentally friendly shape memory smart composite film with three responsive modes. The composite film mainly consists of a bilayer structure composed of a CWTN water-responsive layer and a T-P-L polymer layer. The results indicate that CWTN exhibits excellent water conduction properties. When the CWTN layer is combined with the T-P-L layer, the composite film demonstrates sensitivity to thermal, light and water. The thermal response shape fixation rate and shape recovery rate of the composite film both exceed 85%. The light-responsive shape mode can complete the shape recovery process within one minute. The water-responsive actuation mode of the composite film operates rapidly, completing the water-responsive shape recovery process within 30 seconds. CWTN resolve the issue of slow response speed in traditional water-driven systems. Based on these principles, a flexible self-actuating device simulating the blooming of a bud was fabricated using the shape memory smart composite film. This device also possesses three response modes, each capable of fully simulating the process of flower blooming. Finally, a cyclic programming method was proposed based on the designability of the shape memory smart composite material, enabling it to transform into various shapes according to predefined patterns. This research can be applied in fields such as soft robotics, flexible actuating joints, and decorative settings, providing a new design approach for flexible actuators, and expend the application space of CMC and lignin. Declarations Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution Fang Suo: Writing -original draft, Writing - review & editing, Methodology, Conceptualization, Investigation, Data curation, Visualization, Validation, Software; Zhongyang bai: Data curation, Formal analysis, Visualization, Validation; Xiangwei Ma: Data curation, Visualization, Investigation; Yongtao Yao: Writing - review & editing, Supervision, Methodology, Conceptualization, Formal analysis, Project administration; Yanju liu: Writing - review & editing, Methodology, Visualization. Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant No. 12272112). Data availability The authors do not have permission to share data. References Yasa O, Toshimitsu Y, Michelis MY, Jones LS, Filippi M, Buchner T, Katzschmann RK (2023) An Overview of Soft Robotics. Annual Rev Control Rob Auton Syst 6(1):1–29 Laschi C, Mazzolai B, Cianchetti M (2016) Soft robotics: Technologies and systems pushing the boundaries of robot abilities. 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Wood Sci Technol 54(4):787–820 Li J, Liu W, Qiu X, Zhao X, Chen Z, Yan M, Fang Z, Li Z, Tu Z, Huang J (2022) Lignin: a sustainable photothermal block for smart elastomers. Green Chemistry: Int J Green Chem Resource : GC 24(2):823–836 Sessini V, Navarro-Baena I, Arrieta MP, Dominici F, López D, Torre L, Kenny JM, Dubois P, Raquez J, Peponi L (2018) Effect of the addition of polyester-grafted-cellulose nanocrystals on the shape memory properties of biodegradable PLA/PCL nanocomposites. Polym Degrad Stabil 152:126–138 Joo Y, Cha J, Gong M (2018) Biodegradable shape-memory polymers using polycaprolactone and isosorbide based polyurethane blends. Mater Sci Engineering: C 91:426–435 Hohimer CJ, Petrossian G, Ameli A, Mo C (2020) Pötschke, 3D printed conductive thermoplastic polyurethane/carbon nanotube composites for capacitive and piezoresistive sensing in soft pneumatic actuators. 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Nano Today 38:101202 Wong YS, Salvekar AV, Zhuang KD, Liu H, Birch WR, Tay KH, Huang WM, Venkatraman SS (2016) Bioabsorbable radiopaque water-responsive shape memory embolization plug for temporary vascular occlusion. Biomaterials 102:98–106 Shuai C, Wang Z, Peng S, Shuai Y, Chen Y, Zeng D, Feng P (2022) Water-responsive shape memory thermoplastic polyurethane scaffolds triggered at body temperature for bone defect repair. Mater Chem Front 11:1456–1469 Fang Z, Kuang Y, Zhou P, Ming S, Zhu P, Liu Y, Ning H, Chen G (2017) Poly(vinyl alcohol) by Wettability Contrast Strategy, ACS Appl. Mater Interfaces 9(6):5495–5502Programmable Shape Recovery Process of Water-Responsive Shape-Memory Salvekar AV, Huang WM, Xiao R, Wong YS, Venkatraman SS, Tay KH, Shen ZX (2017) Water-Responsive Shape Recovery Induced Buckling in Biodegradable Photo-Cross-Linked Poly(ethylene glycol) (PEG) Hydrogel, Acc. Chem Res 50(2):141–150 Bernsdorf A, Brand H, Hellmann R, Köckerling M, Schulz A, Villinger A, Voss K (2009) Synthesis, Structure, and Bonding of Weakly Coordinating Anions Based on CN Adducts. J Am Chem Soc 131(25):8958–8970 Zhang W, Zhang X, Liang M, Lu C (2008) Mechanochemical preparation of surface-acetylated cellulose powder to enhance mechanical properties of cellulose-filler-reinforced NR vulcanizates. Compos Sci Technol 68(12):2479–2484 Tian M, Qu L, Zhang X, Zhang K, Zhu S, Guo X, Han G, Tang X, Sun Y (2014) Enhanced mechanical and thermal properties of regenerated cellulose/graphene composite fibers. Carbohydr Polym 111:456–462 Additional Declarations No competing interests reported. Supplementary Files SupplementaryInformation.docx Cite Share Download PDF Status: Published Journal Publication published 28 Apr, 2025 Read the published version in Wood Science and Technology → Version 1 posted Editorial decision: Revision requested 21 Jan, 2025 Reviews received at journal 12 Nov, 2024 Reviews received at journal 28 Oct, 2024 Reviewers agreed at journal 23 Oct, 2024 Reviews received at journal 21 Oct, 2024 Reviewers agreed at journal 20 Oct, 2024 Reviewers agreed at journal 29 Sep, 2024 Reviewers invited by journal 25 Sep, 2024 Editor assigned by journal 22 Sep, 2024 Submission checks completed at journal 05 Sep, 2024 First submitted to journal 04 Sep, 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. 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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-5034691","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":360368998,"identity":"dd99e15a-4b47-4f00-9710-306e16269396","order_by":0,"name":"Fang Suo","email":"","orcid":"","institution":"Harbin Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Fang","middleName":"","lastName":"Suo","suffix":""},{"id":360368999,"identity":"0f6c5393-6072-487c-9cb9-e696b856f7b2","order_by":1,"name":"Zhongyang Bai","email":"","orcid":"","institution":"Northeast Forestry 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1","display":"","copyAsset":false,"role":"figure","size":235489,"visible":true,"origin":"","legend":"\u003cp\u003eThe synthesis process of the shape memory smart composite.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/7995a3db28fb375f1803cc95.png"},{"id":66166845,"identity":"d69c885b-cd2a-4132-894b-61ef4a0f98c3","added_by":"auto","created_at":"2024-10-08 10:02:23","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":193764,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The water absorption properties of CWTN films, (b) FTIR analysis of CMC and CWTN, (c) optical microscopy imaging of CWTN(Ⅰ), SEM of interlayer connection(Ⅱ), SEM and water contact angle of CWTN(Ⅲ), T-P-L(Ⅳ), (d) absorbance of CWTN and T-P-L, (e) heating rate of CWTN and T-P-L under illumination.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/8b6e72a232ce31767db5049e.png"},{"id":66166842,"identity":"8b1c0991-8775-4310-953b-3d8f882fed43","added_by":"auto","created_at":"2024-10-08 10:02:23","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":120559,"visible":true,"origin":"","legend":"\u003cp\u003eThree response modes of the shape memory smart composite film.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/ce20287fe91fc292da21d14b.png"},{"id":66166841,"identity":"12e8b790-ba66-4762-b8b7-97f2b92a3f02","added_by":"auto","created_at":"2024-10-08 10:02:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":123760,"visible":true,"origin":"","legend":"\u003cp\u003eThe thermal response (a) shape fixation rate and (b)shape recovery rate of the shape memory smart composite film, (c) the relationship between fixation rate and time, and (d) shape recovery rate in the water-responsive mode, (e) light-responsive shape recovery rate, (f) the mechanical properties of the shape memory smart composite film.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/222a861e25ae383a3a96d7e3.png"},{"id":66166843,"identity":"002fc498-8ca2-4fb2-a554-165e530a9dd3","added_by":"auto","created_at":"2024-10-08 10:02:23","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":194294,"visible":true,"origin":"","legend":"\u003cp\u003e(a) 3D printing process, (b) the structure of the self-actuating device, (c) three response modes of the self-actuating device.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/240d3765c5083dbd55d5d0f3.png"},{"id":81988201,"identity":"71518380-21de-4c25-9c08-e67ac1351c46","added_by":"auto","created_at":"2025-05-05 16:08:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1717787,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/d7a5969f-90fa-47cd-8159-ad6c63c866be.pdf"},{"id":66166846,"identity":"a104c217-1b10-4025-b715-e314c98c26f6","added_by":"auto","created_at":"2024-10-08 10:02:23","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":367854,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-5034691/v1/1ee17382dd9cc98a02adbd1d.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Environmentally Friendly Shape Memory Smart Composite Material with Multiple Response Modes","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eSoft robots are a class of robots primarily composed of flexible materials, capable of interacting with environmental factors and exhibiting corresponding responsive behaviors. Soft robots can be composed of structures driven by flexible joints actuating rigid materials, or they can be entirely manufactured from flexible materials. Soft robots made from flexible materials are not constrained by the physical space limitations of their working environment, allowing for arbitrary changes in shape and structure to accomplish their task objectives[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The advancement of disciplines such as bionics, materials science, and mechanics has led to the extensive application of soft robots and flexible actuation systems in fields including biomedical engineering, civil infrastructure, environmental exploration, and aerospace. As the demand for such devices increases, soft robots must evolve to meet various application requirements. Developing multifunctional, multi-purpose soft robots with enhanced adaptability to complex environments has become a current challenge.\u003c/p\u003e \u003cp\u003eSmart materials serve as the driving core of soft robots, responsible for converting external environmental energy into kinetic or other forms of energy, enabling complex shape changes or functional expressions. Due to the driving action of intelligent materials, soft robots can exhibit functionalities such as positional changes, object manipulation, and shape modulation under external environmental stimuli[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. With the advancement of intelligent material technology, including the emergence of novel intelligent materials such as smart responsive hydrogels[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], shape memory polymers[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], and shape memory alloys[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], the diversity of driving mechanisms and response conditions for soft robots has increased. The response mode of the driving mechanism is crucial for energy conversion in soft robots, and it can determine their application environment and functional selection. Currently, the majority of driving modes include thermal[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], optical[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], humidity[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], and magnetic driving[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. For current research and applications, designing multifunctional smart materials can maximize the potential of soft robots. Smart composite materials designed with various responsive materials can offer multifunctional advantages, thereby enhancing their application value. Additionally, these smart composites should also possess environmentally friendly and biodegradable properties to broaden their range of applications.\u003c/p\u003e \u003cp\u003eCellulose is a kind of forestry product extracted from wood with environmentally friendly characteristics[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Carboxymethyl cellulose (CMC) molecules contain a large number of carboxyl and hydroxyl groups, exhibiting excellent hydrophilicity and water absorption properties[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Thus, it can serve as a viable option for hydrophilic shape memory material raw materials. Additionally, it boasts advantages of low cost and good biodegradability[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Lignin is a complex polymer extracted from wood cell walls also with environmentally friendly characteristics[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Lignin molecules contain numerous conjugated functional groups, showcasing excellent photo-thermal performance and thus can serve as filler for photo-response functionalities. Lignin possesses characteristics such as high yield, environmental friendliness, and significant potential for application[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Polycaprolactone (PCL) is a widely used polymer in the field of biomedicine, characterized by excellent biocompatibility, often employed in medical device packaging and medical equipment manufacturing. Furthermore, due to its low melting point, PCL exhibits temperature-sensitive characteristic which makes it suitable as a switch for thermal response driving modes[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Thermoplastic polyurethane (TPU) is a commonly used elastomeric material at present, applicable in aerospace, medical devices, 3D printing, among other fields. TPU demonstrates good thermal stability and stable mechanical properties. As TPU is an amorphous polymer that lack of crystalline structure, it possesses higher toughness and elongation compared to commonly used materials such as PE, PP, and PVC, rendering it more suitable as a framework material for shape memory smart composite[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, this study presents the design of a shape memory smart composite device for operation in wet and aquatic environments, featuring water, light, and thermal response modes. Inspired by capillary phenomena in plant leaf veins and transpiration, a CMC water transport network (CWTN) was fabricated using CMC as the raw material. This network possesses a structure characterized by loose porosity, allowing rapid absorption of moisture in humid environments and subsequent release in dry conditions, thereby achieving water-responsive functionality. In contrast to traditional water-responsive driving materials relying on hydrophilic functional groups such as polyvinyl alcohol and polyethylene glycol, the CWTN exhibits abundant hydrophilic functional groups at the microscopic level, endowing the material with hydrophilicity. Moreover, the physical effects generated at the macroscopic level facilitate accelerated water transport, potentially enhancing the responsiveness of water-responsive driving devices. Shape memory polymer (SMP) exhibits structural stability under normal conditions. Utilizing TPU, PCL, and lignin, SMP with dual light and thermal response functionalities were manufactured. These materials demonstrate excellent light and thermal response shape memory behavior. By integrating SMP with the CWTN, a smart composite with three response modes was fabricated. Finally, an environmentally friendly self-driven device with three response modes was successfully developed using this material design.\u003c/p\u003e"},{"header":"2 Experiment","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eCMC was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd. Ferric chloride was obtained from Tianjin Hengxing Chemical Preparation Co., Ltd. Citric acid (CA) was acquired from Tianjin Dongli District Tianda Chemical Reagent Factory. TPU (1185A) was procured from BASF, Germany, and PCL (CapaTM 6800) was sourced from Perstorp, Sweden. Lignin, with a molecular weight of 3000\u0026ndash;5000 g/mol, was purchased from Lingyu Chemical Co., Ltd. (China). Dimethylformamide (DMF) was obtained from Tianjin Yongda Chemical Reagent Co., Ltd. The polytetrafluoroethylene (PTFE) film was purchased from Dongguan Youka Plastic Co., Ltd.\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 Preparation of CWTN films\u003c/h2\u003e \u003cp\u003eAdd 3g of CMC to a beaker containing 100ml of deionized water, and stir the mixture using a magnetic stirrer in a water bath at 80\u0026deg;C for 2 hours until the CMC is completely dissolved. Dissolve 2.7g of ferric chloride and 1.05g of CA in a beaker containing 100ml of deionized water to prepare the ferric ion/CA cross-linking agent (Fe/CA). Ultrasonicate the prepared CMC solution for 30 minutes to remove air bubbles, then pour it into a silicone mold with dimensions of 50mm in length, 50mm in width, and 5mm in depth. Place the mold in an electric blast drying oven (Shanghai Yiheng Scientific Instrument Co., Ltd) and dry at 80\u0026deg;C for 40 minutes. After drying, cool the mold containing the CMC gel to room temperature and pour in the Fe/CA cross-linking agent, allowing it to stand for 1 hour. Remove the cross-linked film from the mold and place it in a freeze dryer (Ningbo Xinzhi Biotechnology Co., Ltd) to dry thoroughly for 24 hours to obtain the CWTN film.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Preparation of T-P-L composite material and 3D printing filament\u003c/h2\u003e \u003cp\u003eBased on our previous research, the optimal ratio of the composite material was selected. TPU, PCL, and lignin were dried for one day and then uniformly mixed in a ratio of 12:8:5. The mixture was fed into a twin-screw extruder (SJSH-30, Nanjing Rubber and Plastics Machinery Plant Co., Ltd., China) for thorough mixing to obtain the T-P-L composite material. The extruder temperatures were set at 160\u0026deg;C, 175\u0026deg;C, 180\u0026deg;C, 185\u0026deg;C, 180\u0026deg;C, and 175\u0026deg;C. The T-P-L composite material was then fed into a crusher (SMP-200, Zhangjiagang Songben Plastic Machinery Co., Ltd., Zhangjiagang, China) to obtain composite material pellets.\u003c/p\u003e \u003cp\u003eThe composite material pellets were fed into a single-screw extruder filament machine (SHSJ25, Dongguan Songhu Plastic Machinery Co., Ltd, China). The temperature zones were set at 175\u0026deg;C, 185\u0026deg;C, and 150\u0026deg;C. The screw speed was set at 30 rpm, and the traction speed was controlled within the range of 10 rpm to 15 rpm to maintain a filament diameter of 1.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1 mm. The filament was collected using a spool for future use. A commercial 3D printer (Changsha Fuzhi Technology Co., Ltd) was used for 3D printing, with the printing parameters provided in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Preparation of shape memory smart composite films\u003c/h2\u003e \u003cp\u003ePlace the CWTN film and the printed film-like structure separately on two iron plates covered with polytetrafluoroethylene (PTFE) film. Using a dropper, apply a certain amount of dimethylformamide solution onto the CWTN film. Once the CWTN film has fully absorbed the dimethylformamide solution, press the 3D-printed film onto the CWTN film to bond the two layers together. Then, fully dry the bilayer film structure at 40\u0026deg;C to remove the dimethylformamide solution, resulting in a shape memory smart composite film with a bilayer film structure.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Characterization Methods\u003c/h2\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Water absorption rate of CWTN films\u003c/h2\u003e \u003cp\u003eMeasure the initial weight of the CWTN film using an electronic balance. Hold one end of the CWTN film with tweezers and immerse the other end in water dyed red with ink. Observe the height of the water rise every 1 minute and measure the weight of the film in this state.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Fourier transform infrared spectroscopy (FTIR)\u003c/h2\u003e \u003cp\u003eTo investigate the promoting effect of internal polymer functional groups on water molecule absorption, Fourier Transform Infrared Spectroscopy (FTIR) (Shimadzu, Japan) was used to test CMC, CA, and CWTN films at room temperature. The testing range was from 500 cm⁻\u0026sup1; to 4000 cm⁻\u0026sup1;.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.3.3 Morphological observation\u003c/h2\u003e \u003cp\u003eThe morphology of the CWTN films was observed using a polarizing microscope (MODEL BXSSMTRF-S, Olympus Corporation, Japan). The shape memory smart composite film was gold-sputtered and observed using a scanning electron microscope (SEM; Apreo S HiVac, Thermo Scientific, USA) at a voltage of 20 kV to observe the morphology of both surfaces and the interface of the middle layer of the shape memory smart composite films.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.3.4 Hydrophilic-hydrophobic effect testing of shape memory smart composite films\u003c/h2\u003e \u003cp\u003eThe static contact angle was measured at room temperature using a fully automated video contact angle measurement instrument (OCA20, DataPhysics Instruments, Germany). The test liquid used was water.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e2.3.5 Mechanical properties\u003c/h2\u003e \u003cp\u003eThe tensile properties of the composite films were tested using a universal testing machine (CMT5504, MTS Systems China Co., Ltd., China) at a testing speed of 10 mm/s. With the CWTN film thickness fixed at 0.4mm, T-P-L films of varying thicknesses (0.2mm, 0.3mm, 0.4mm, 0.5mm, and 0.6mm) were selected to create samples. These samples were cut into rectangular shapes measuring 50mm in length and 10mm in width for mechanical property measurements.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e2.3.6 Optical properties and photothermal energy conversion performance\u003c/h2\u003e \u003cp\u003eThe optical absorption properties of both surfaces of the composite films were tested using an ultraviolet-visible spectrophotometer (CARY100; Agilent Technologies Inc., USA). The testing range was from 200 nm to 800 nm, and the test samples were prepared as 20 mm diameter discs.\u003c/p\u003e \u003cp\u003eThe photothermal energy conversion performance of both surfaces of the composite films was tested using a xenon lamp light source system (CEL-HXF300, Beijing China Education Au-light Co., Ltd., China). A light power meter (CEL-FZ-A; Beijing China Education Au-light Co., Ltd., China) was used to adjust the light intensity to 200 mW/cm\u0026sup2;. An infrared camera (T1, Zhejiang Dali Technology Co., Ltd., Zhejiang, China) was used to observe the temperature increase of both surfaces of the composite films under illumination. Temperature measurements were recorded by every 5 seconds.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e2.3.7 Thermal responsive shape memory performance\u003c/h2\u003e \u003cp\u003eCut the composite film into rectangular specimens with dimensions of 30 mm in length and 15 mm in width. Place the specimens in an electric blast drying oven and heat to 60\u0026deg;C. Once the specimens have softened, bend them into a U-shape and fix them in this position. Cool the specimens to room temperature and record the bending angle, which is the shape fixation angle. Then, place the specimens back into the blast drying oven and allow them to complete the shape recovery process. Remove the specimens and cool them to room temperature. Record the angle of the specimens at this point as the shape recovery angle. Calculate the shape fixation rate \u003cem\u003e(R\u003c/em\u003e\u003csub\u003e\u003cem\u003ef\u003c/em\u003e\u003c/sub\u003e) and shape recovery rate (\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e) of the shape memory smart composite films using the following formulas:\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"388\" height=\"127\"\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eθ₀\u003c/em\u003e is the initial angle, θ is the shape fixation angle, and \u003cem\u003eθ'\u003c/em\u003e is the shape recovery angle.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e2.3.8 Light responsive shape memory performance\u003c/h2\u003e \u003cp\u003ePlace rectangular specimens with dimensions of 30 mm in length and 15 mm in width into an electric blast drying oven set at 60\u0026deg;C. Once the specimens have softened, bend them into a U-shape. Fix the specimens and cool them to room temperature, then measure the bending angle, which is the shape fixation angle. Place the U-shaped specimens on a horizontal plane with the U-connection facing upwards. Use a xenon lamp light source system to irradiate the U-shaped specimens from top to bottom, and record the light-responsive shape recovery process using a digital camera. Use Photoshop (Adobe Systems Software Ireland Ltd., USA) software on a computer to calculate the shape recovery angle at 10-second intervals. The formulas for calculating the shape fixation rate and shape recovery rate are given by equations (\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1.1\u003c/span\u003e) and (\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e1.2\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e2.3.9 Water responsive shape memory performance\u003c/h2\u003e \u003cp\u003eSoak the rectangular specimens in deionized water for 30 minutes. Then, remove the specimens and allow them to air dry, during which the specimens will bend. Measure the bending angle of the specimens as shape fixation rate at 1-minute intervals for a total duration of 5 minutes. Subsequently, immerse the specimens in water and use a digital camera to record the water-responsive shape recovery process. Use Photoshop software to measure the shape recovery angle of the specimens on a computer at 5-second intervals. The formulas for calculating the shape fixation rate and shape recovery rate are given by equations (\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1.1\u003c/span\u003e) and (\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e1.2\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Response characteristics of shape memory smart composite material films\u003c/h2\u003e \u003cp\u003eThe shape memory smart composite films with water-responsive functionality require a module that responds to water. Inspired by the principles of water transport and transpiration in plant leaves, designed and fabricated the CWTN water-responsive module, which possesses both water transport and water dispersal capabilities. This module is made using CMC, a material rich in hydrophilic functional groups[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea illustrates the water absorption effect of the CWTN water-responsive module, where water is transported upward from the bottom of the CWTN film, overcoming gravity. In just 4 minutes, the weight of the CWTN film increases by 600%, demonstrating that the water-responsive module exhibits excellent hydrophilicity and a rapid response rate to water transport.\u003c/p\u003e \u003cp\u003eTo further analyze the water-responsive mechanism of the CWTN water-responsive module, we investigated the hydrophilic mechanism of CWTN from both macroscopic and microscopic perspectives. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb presents the FTIR spectra of CWTN and CMC. The spectrum of CMC shows distinct characteristic peaks of COO- at 1416 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1592 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Additionally, a broad peak for -OH appears between 3000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 3650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. These hydrophilic functional groups are crucial for the hydrophilicity of CMC[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The spectrum of CWTN exhibits the characteristic peaks of COO- at 1416 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1592 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Due to the presence of CA as the chelating agent add to the system, a vibration peak for carboxylic acid C\u0026thinsp;=\u0026thinsp;O appears at 1728 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e(Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). A broad peak for -OH is also observed between 3000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 3650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. This indicates that CWTN retains most of the hydrophilic functional groups of CMC at the microscopic level, thus endowing the CWTN film with excellent hydrophilicity. This is a significant reason for the rapid water-responsive functionality of the CWTN film.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec(Ⅰ) shows the surface imaging of CWTN observed using a microscope. It can be seen that CWTN exhibits a macroscopic crosslinked network structure with large pores. This phenomenon is due to the complexation reaction of Fe\u0026sup3;⁺ with CMC and CA, resulting in the formation of a three-dimensional channel network cross-linked structure, the reaction mechanism was shown in Fig. S2. These structures are preserved during the freeze-drying process, resulting in formations similar to the vascular channels and stomata in plant leaves. Upon contact with water, surface tension facilitates the filling of these channels with water. The crosslinked porous structure ensures uniform contact between water and the CWTN surface, thereby increasing the contact area with water. The combined effect of numerous hydrophilic functional groups and the crosslinked porous structure endows the CWTN film with strong water-responsive functionality.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec(Ⅱ) shows the SEM image of the interlayer connection in the bilayer film structure, observing that the two layers are tightly bonded together. This is due to the dissolution of the TPU and PCL on the surface layer of the T-P-L film by DMF, which increases the fluidity of the dissolved polymers, allowing them to penetrate into the surface layer of the CWTN film. This phenomenon is intensified under pressure. Upon drying, the polymers that have penetrated into the CWTN film precipitate due to the evaporation of the solvent and bond with the T-P-L composite film, resulting in the CWTN film and T-P-L film adhering to each other, thereby forming a stable bilayer film structure.\u003c/p\u003e \u003cp\u003eTo investigate the hydrophilic anisotropy of the shape memory smart composite films, studied the hydrophilic and hydrophobic properties of the CWTN layer and the T-P-L layer, respectively. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec(Ⅲ) shows the CWTN surface as observed under a SEM. After the CWTN film was adhered to the T-P-L composite film, the crosslinked porous structure was still retained, giving one side of the composite film excellent hydrophilic properties. The static contact angle test results show that the water contact angle of the CWTN surface is only 19\u0026deg;. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec(Ⅳ) shows the SEM imaging of the T-P-L composite surface. The surface exhibits protrusions caused by lignin agglomerating and exposing on the polymer surface. The static contact angle test results show that the water contact angle of the T-P-L composite surface reaches 80\u0026deg;, significantly different from the CWTN surface. This is because TPU and PCL are hydrophobic materials[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This result demonstrates that the shape memory smart composite film exhibits obvious hydrophilic anisotropy on its two sides. The T-P-L composite film has good stability in water environments, thus when the CWTN film absorbs water and expands or loses water and contracts, it provides the bending and recovery force for the composite film. This is the fundamental mechanism enabling the water-responsive mode of the shape memory smart composite film.\u003c/p\u003e \u003cp\u003eThe shape memory smart composite film exhibits different environmental response modes. According to our previous research, T-P-L is a composite material with excellent thermos-responsive and light-responsive shape memory properties, having a relatively low shape memory transition temperature (T\u003csub\u003etran\u003c/sub\u003e), at 53\u0026deg;C[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Consequently, the shape memory smart composite film also possesses corresponding thermos-responsive and light-responsive functionalities. Since heat acts on the film through conduction, the composite film exhibits shape memory properties similar to SMP with no anisotropic characteristics in response to heat. Here, we focus on investigating the light-responsive properties of the composite film.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed shows the absorbance of both sides of the composite film. As illustrated, the T-P-L layer exhibits good absorption in both the ultraviolet and visible light ranges. This is due to the conjugated functional group structures within lignin that convert light energy into thermal energy[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Consistent with previous analysis, the T-P-L composite film surface has many exposed lignin agglomerates, resulting in excellent light absorption. The CWTN layer shows relatively low absorbance in the visible light range, indicating that the CWTN layer does not have significant light-responsive properties, and the response to light is uneven between the two sides of the composite film.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee depicts the temperature increase on both sides of the composite film under xenon lamp illumination. The T-P-L layer demonstrates a good photothermal conversion effect, capable of converting light energy into heat energy within a short time, reaching the T\u003csub\u003etran\u003c/sub\u003e in about 33 seconds. In contrast, the CWTN layer does not reach the transition temperature within 60 seconds. Therefore, it can be concluded that the photosensitive layer of the composite film is the T-P-L layer, which is significant for the structural design of self-actuating device.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Response modes of shape memory smart composite films\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the shape memory smart composite film has three independent responsive actuation modes to meet the demands of different usage environments: thermal responsive mode, light responsive mode, and water responsive mode. The shape memory smart composite film is composed of a CWTN water-responsive film and a T-P-L film made of shape memory polymers. The thermal and light responsive actuation modes rely on the shape memory effect of the T-P-L film. These two responsive actuation modes are similar to the shape memory effect of shape memory polymers. After the shape is programmed and fixed by external force, the material undergoes a shape recovery process. The water-responsive mode is achieved through the dry-shrink and wet-swell properties of the CWTN film, it is a commonly observed water response driving pattern[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. This phenomenon occurs on only one side of the composite film, while the other side remains stable in the water environment. When the CWTN film loses water, one side of the composite film contracts, causing the composite film to bend. When the CWTN film reabsorbs water, the composite film returns to its original shape. This process can be entirely controlled by water, eliminating the traditional need for external force programming in responsive actuators.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea and Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb shows the thermal responsive actuation performance of the shape memory smart composite film. Since the thermal responsive actuation performance of the shape memory smart composite film originates from the thermal responsive shape memory performance of the T-P-L composite material, and CWTN itself does not have thermal responsive actuation capabilities. Therefore, when the T-P-L layer is relatively thin, the shape fixation ability of the composite film is poor. As the thickness of the T-P-L layer increases, the shape fixation rate increases. When the thickness of the T-P-L layer reaches 0.5 mm, the shape fixation rate exceeds 85%. The shape recovery ability of the shape memory smart composite films was shown in the relationship of recovery rate and thickness. It can be seen that regardless of the thickness of the T-P-L layer, the composite film exhibits excellent shape recovery ability, with shape recovery rates above 90%. During the actuation process of the composite film, the shape recovery ability of T-P-L is primarily utilized. The shape memory smart composite film demonstrates good thermal responsive actuation performance. Based on comprehensive comparison, when the T-P-L thickness reaches or exceeds 0.5 mm, the shape memory smart composite film exhibits optimal thermal responsive actuation performance.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe water responsive actuation mode is driven by the CWTN water actuation module. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec shows the relationship between the fixation rate of the composite film and time as the film is exposed to air and the water evaporates naturally. Due to the abundance of pore-like structures similar to plant leaf stomata on the surface of the CWTN film, water easily dissipates into the air. As the water dissipates, the pore structure within the CWTN layer contracts and undergoes volumetric shrinkage, leading to the bending of the composite film. The composite film can achieve 100% bending rate within four minutes. At this point, a certain amount of elastic potential energy is stored within the T-P-L layer, and the bending process stops once the stress between the T-P-L layer and the CWTN layer reaches equilibrium. As the thickness of the T-P-L layer increases, the bending speed slows down because the T-P-L layer gradually dominates the overall performance of the composite film. However, when the thickness of the T-P-L layer reaches 0.6 mm, the composite film can still complete the bending process within five minutes.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed shows the relationship between the shape recovery rate of the composite film in water and time. It can be seen that the composite film has a very rapid water-driven shape recovery process. When the composite film is immersed in water, the water enters the internal structure along the pores on the surface of the CWTN layer, causing the pores within the CWTN layer to absorb water and expand. At this point, the T-P-L layer also releases the stored elastic potential energy, assisting the composite film in returning to its original shape. As the thickness of the T-P-L layer increases, the water-driven shape recovery ability of the composite film also increases. Therefore, it can be concluded that the water-responsive bending process of the composite film is determined by the CWTN layer, while the shape recovery process is the result of the combined action of both the CWTN layer and the T-P-L layer. Compared to previous studies, this shape memory material demonstrates a remarkably rapid water-responsive recovery process[\u003cspan additionalcitationids=\"CR33\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. This can be attributed to the excellent hydrophilic properties of the CWTN, allowing the shape memory smart composite film to complete the water-responsive recovery process in almost 30 seconds.\u003c/p\u003e \u003cp\u003eThe light responsive actuation mode relies on the photothermal conversion ability of the T-P-L layer, so the light responsive actuation process of the composite film is similar to the light responsive shape recovery process of shape memory polymers. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee shows the light responsive actuation process of the composite film. It can be seen that the thickness of the T-P-L layer is not related to the light responsive actuation performance. Previous studies have confirmed that the light responsive shape memory ability of T-P-L composites is related to the lignin content in the composite material[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Therefore, with the same proportion of lignin, all samples exhibit similar light responsive actuation performance. Additionally, the actuation process can be completed within 60 seconds, with a shape recovery rate of up to 88%. Consequently, the composite film demonstrates a rapid responsive light responsive actuation characteristic.\u003c/p\u003e \u003cp\u003eMechanical performance is fundamental to the operation of shape memory performance, as they must possess sufficient mechanical properties to maintain shape stability and operational stability during use. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef shows the tensile strength of the composite films. Since ionic bonds are weak coordination types of chemical bonds, the CWTN film itself does not possess good mechanical properties[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Therefore, as the thickness of the T-P-L film increases, the tensile strength gradually increases. The composite film achieves the highest tensile strength when the T-P-L film thickness reaches 0.5 mm. When the thickness of the T-P-L film exceeds 0.5 mm, the tensile strength decreases. This is due to the fact that the raw material of the CWTN film is cellulose, whose internal molecular chains are arranged in a fibrous manner. During the adhesion process of the two films, the two materials wrap around each other at the contact surface. Previous studies have demonstrated that fibrous fillers can increase the mechanical properties of polymers to a certain extent, and proper proportion adjustment can achieve optimal mechanical performance[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Therefore, the samples with different ratios of CWTN to T-P-L exhibit varying mechanical properties. When the thickness of the T-P-L film exceeds 0.5 mm, the excessive polymer composite material begins to dominate the mechanical properties of the film, leading to a decrease in tensile strength. Therefore, the optimal mechanical performance is achieved with a CWTN film thickness of 0.4 mm and a T-P-L film thickness of 0.5 mm.\u003c/p\u003e \u003cp\u003eAfter comprehensive consideration, the optimal ratio was determined to be a T-P-L layer thickness of 0.5 mm and a CWTN layer thickness of 0.4 mm. This ratio was then used to design and manufacture self-actuating device with three response modes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Flexible self-actuating device with three actuation modes\u003c/h2\u003e \u003cp\u003eShape memory smart composite films can be used to create self-actuating devices that respond to different environmental stimuli. By adjusting the structural distribution of the CWTN layer and the T-P-L layer, self-actuating devices can be designed to perform specific functions. In this study, a flexible self-actuating device with three actuation modes, thermal, light, and water, which was fabricated using shape memory smart composite films. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, the structure of the T-P-L layer was designed and fabricated using a commercial 3D printer. A petal structure with five blades, with a diameter of 50 mm and a thickness of 0.5 mm, was printed using T-P-L composite filament. The CWTN film was cut into a petal structure similar to that of the printed T-P-L layer. The assembly scheme of the self-actuating device is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb. Each petal is controlled by a shape memory smart composite film composed of two layers, mimicking the opening of a flower. Previous studies have demonstrated the poor photothermal energy conversion of the CWTN layer. To ensure that light irradiation from the CWTN layer side can still achieve light responsiveness, the petal ends of the CWTN layer were removed and adhered to the T-P-L layer, exposing a portion of the T-P-L film. The CWTN layer serves as the water-responsive sensing layer, while the exposed T-P-L layer acts as the light-responsive region. This design allows the petals of the self-actuating device to bend in the same direction under all three actuation modes, achieving consistent responsive behavior.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, the self-actuating device successfully achieved three actuation modes. These three actuation modes operate independently. By heating the self-actuating device to T\u003csub\u003etran\u003c/sub\u003e, the T-P-L layer softens, making the device easy to deform. Under the action of external force, each petal of the flower is fixed in an upright shape, mimicking an unbloomed bud. The bud shape serves as the initial shape for the thermal and light responsive actuation modes. When the device is reheated to Ttran, the petals soften and automatically display a blooming process due to the shape recovery performance of the T-P-L layer. Subsequently, the petals can be fixed in an upright shape and cooled, allowing the self-actuating device to return to its initial bud shape.\u003c/p\u003e \u003cp\u003eThe light responsive actuation mode is similar to the thermal responsive mode. A xenon lamp is used to vertically irradiate the self-actuating device in its bud shape. Each of the five petals has an exposed T-P-L layer that serves as the photosensitive area. These photosensitive areas convert light energy into thermal energy and conduct it to the petals. When the heat in the petals raises the temperature to Ttran, the flower opens. The device completes the process of mimicking flower blooming under the influence of light. Subsequently, external force is used to return the flower to its initial shape, and it is cooled and fixed to complete one actuation cycle.\u003c/p\u003e \u003cp\u003eThe cycle of the water responsive actuation mode can be entirely controlled by water. The self-actuating device is soaked in water for 30 minutes. Then, the device is placed in the air to dry naturally. Due to the evaporation of water, the device bends towards the CWTN layer side, ultimately reaching the initial shape of the water responsive mode. When the device is re-immersed in water, the CWTN layer absorbs water molecules and expands, causing the self-actuating device to complete the blooming process. Then, when the device is exposed to air again, the pores in the CWTN layer release water molecules into the air, causing the CWTN layer to contract. The already open flower reverts to a bud. The water responsive mode eliminates the need for external force to fix the shape, making it convenient to use in water environments.\u003c/p\u003e \u003cp\u003eFinally, based on the characteristics of the water response model, a controllable programming strategy is proposed. As shown in Fig. S3, in this structure, CWTN is arranged on both sides of T-P-L. Specific CWTN modules can be activated at designated locations as needed to trigger their water responsive functions, allowing for predetermined shape changes. Moreover, all shape transformations in this structure can be repeatedly cycled without external force. The combination strategy of CWTN and T-P-L enables the development of various cyclic driving modes, providing a solution for expanding the application space of flexible actuators and enhancing environmental adaptability.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn this study, a feasible method was developed for making environmentally friendly shape memory smart composite film with three responsive modes. The composite film mainly consists of a bilayer structure composed of a CWTN water-responsive layer and a T-P-L polymer layer. The results indicate that CWTN exhibits excellent water conduction properties. When the CWTN layer is combined with the T-P-L layer, the composite film demonstrates sensitivity to thermal, light and water. The thermal response shape fixation rate and shape recovery rate of the composite film both exceed 85%. The light-responsive shape mode can complete the shape recovery process within one minute. The water-responsive actuation mode of the composite film operates rapidly, completing the water-responsive shape recovery process within 30 seconds. CWTN resolve the issue of slow response speed in traditional water-driven systems. Based on these principles, a flexible self-actuating device simulating the blooming of a bud was fabricated using the shape memory smart composite film. This device also possesses three response modes, each capable of fully simulating the process of flower blooming. Finally, a cyclic programming method was proposed based on the designability of the shape memory smart composite material, enabling it to transform into various shapes according to predefined patterns. This research can be applied in fields such as soft robotics, flexible actuating joints, and decorative settings, providing a new design approach for flexible actuators, and expend the application space of CMC and lignin.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eDeclaration of competing interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eFang Suo: Writing -original draft, Writing - review \u0026amp; editing, Methodology, Conceptualization, Investigation, Data curation, Visualization, Validation, Software; Zhongyang bai: Data curation, Formal analysis, Visualization, Validation; Xiangwei Ma: Data curation, Visualization, Investigation; Yongtao Yao: Writing - review \u0026amp; editing, Supervision, Methodology, Conceptualization, Formal analysis, Project administration; Yanju liu: Writing - review \u0026amp; editing, Methodology, Visualization.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis work was supported by the National Natural Science Foundation of China (Grant No. 12272112).\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe authors do not have permission to share data.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eYasa O, Toshimitsu Y, Michelis MY, Jones LS, Filippi M, Buchner T, Katzschmann RK (2023) An Overview of Soft Robotics. 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Carbohydr Polym 111:456\u0026ndash;462\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"wood-science-and-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wsat","sideBox":"Learn more about [Wood Science and Technology](http://link.springer.com/journal/226)","snPcode":"226","submissionUrl":"https://submission.nature.com/new-submission/226/3","title":"Wood Science and Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Carboxymethyl Cellulose, Lignin, Water response, Shape memory polymer","lastPublishedDoi":"10.21203/rs.3.rs-5034691/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5034691/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCellulose and lignin offer advantages of low cost and environmental friendliness. In this study, a multi-responsive shape memory smart composite material was proposed based on carboxymethyl cellulose and lignin. Lignin imparts photothermal responsiveness to the composite, while cellulose provides water responsiveness. A bio-inspired structure that mimicking the water transport mechanism of plant leaves was developed to improve the water responsive functionalities of composite material (shape recovery within 30 seconds). A self-driven device that mimics the blooming of a flower was successfully fabricated using this composite material. The shape memory smart composite material exhibits a high degree of design flexibility. Based on the mechanisms of water response, a simple structure programming method was proposed, enabling the design of programmable structures with smart and controllable features. This study provides a new approach to the design of multifunctional smart materials, enhancing the application potential of shape memory materials under multiple environmental factors.\u003c/p\u003e","manuscriptTitle":"Environmentally Friendly Shape Memory Smart Composite Material with Multiple Response Modes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-08 10:02:18","doi":"10.21203/rs.3.rs-5034691/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-21T15:10:14+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-12T16:41:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-28T23:20:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"32000509589246985332787314373167493116","date":"2024-10-23T13:37:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-21T14:47:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"297560799818824106055665328404775317628","date":"2024-10-20T22:04:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"245845336401310680363842299984843669581","date":"2024-09-30T02:21:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-09-25T15:50:08+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-09-22T14:54:32+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-09-05T12:21:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Wood Science and Technology","date":"2024-09-05T02:40:55+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"wood-science-and-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wsat","sideBox":"Learn more about [Wood Science and Technology](http://link.springer.com/journal/226)","snPcode":"226","submissionUrl":"https://submission.nature.com/new-submission/226/3","title":"Wood Science and Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"eb0d8a8e-87e2-45db-8636-37957e6d8c23","owner":[],"postedDate":"October 8th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-05T16:07:09+00:00","versionOfRecord":{"articleIdentity":"rs-5034691","link":"https://doi.org/10.1007/s00226-025-01662-6","journal":{"identity":"wood-science-and-technology","isVorOnly":false,"title":"Wood Science and Technology"},"publishedOn":"2025-04-28 15:57:41","publishedOnDateReadable":"April 28th, 2025"},"versionCreatedAt":"2024-10-08 10:02:18","video":"","vorDoi":"10.1007/s00226-025-01662-6","vorDoiUrl":"https://doi.org/10.1007/s00226-025-01662-6","workflowStages":[]},"version":"v1","identity":"rs-5034691","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5034691","identity":"rs-5034691","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}