A 4D printing polymer composite with light-controlled modulus transition and a preparation method thereof

Abstract

The application discloses a kind of light control modulus transition 4D printing polymer composite material and preparation method thereof, it is related to material technical field, the application is aimed at the problem that structure modulus is difficult to accurately control and lacks function in 4D printing structure, by being compounded photo-thermal nano material to ATHP system, NIR is used to realize the accurate control of printing structure modulus, trace WO 3‑x The existence of NPs helps to realize the controllable photo-thermal characteristics of the printed nanocomposite material, therefore, the ATHP NC system can realize the arbitrary combination of soft and hard regions of the printed structure under the radiation of NIR, compared with multi-material printing, the application reduces the cumbersome steps of changing printing materials, and avoids the interface bonding problem that may be generated during printing, the material preparation process described in the application is simple, the reaction is controllable and can be industrialized production, the cost is low, and only through simple NIR radiation, the in-situ adjustment of the sensitivity of the flexible sensor and the in-situ strengthening of the microstructure of the finger sensor can be realized, which widens the design space of the printed device.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a 4D-printed polymer composite material with light-controlled modulus transformation and its preparation method. Background Technology

[0002] Functionally graded materials (FGMs) have shown great potential for engineering applications in fields such as bioengineering, optoelectronic devices, and soft robotics. FGMs are characterized by a gradual change in composition and structure with volume, leading to corresponding changes in material properties. Their multifunctionality stems from the smooth transition of their constituent phases. They can be designed and manufactured for specific functions and applications. However, because FGMs require continuous spatial variation of mechanical properties, their manufacturing process has always been a major challenge hindering their widespread engineering application. But with advancements in fabrication processes, photopolymerization 4D printing, combining high precision and rapid prototyping capabilities, offers new opportunities—the digital fabrication of FGMs to create complex three-dimensional structures with graded functional properties.

[0003] In 4D printing, research on mechanically gradient shape memory polymer materials is increasing. For example, by simply limiting the light irradiation dose, the degree of reaction conversion in acrylate photopolymers can be easily controlled, thereby controlling the modulus. Additionally, significant modulus differences can be generated by copolymerizing monomer mixtures containing multiple synthetic pathways. Examples include homopolymerization of acrylates and epoxy resins; addition of mercapto-acrylates and homopolymerization of acrylates; optional coumarin cycloaddition reactions; homopolymerization of acrylates with acrylate-amine and epoxy-amine additions; homopolymerization of acrylates with polyurethane condensation; or utilizing the stereochemical differences in photo[trans] and catalytic[cis] polymerization processes involving cis-cyclooctyl. However, many of these chemicals can lead to long-term use problems for the materials. Specifically, the "soft" regions in such systems are intentionally "underpolymerized" to minimize the crosslinking density of the polymer backbone. After printing, these structures contain unreacted acrylates or epoxides, which continue to crosslink and harden when exposed to ambient light or heat. Post-processing can remove unpolymerized material from the polymer network, but the corresponding mass changes can lead to alterations in the structure's shape or stiffness. Besides poor long-term stability, these partially solidified networks are typically non-stretchable (maximum elongation at break less than 40%), making them unsuitable for use in elastomer devices. It can be seen that existing modulus transformation control for FGMs is difficult to achieve and has low performance. Photocontrol, with its high precision, holds promise as an ideal method for controlling the modulus transformation of FGMs. Furthermore, most pure polymer products currently manufactured through 4D printing lack functionality and cannot be used as fully functional parts, hindering the widespread industrial application of 4D-printed polymers. 4D printing of polymer composites can address these issues by combining a polymer matrix with nanofillers to obtain systems with more useful structural or functional properties, such as photothermal, optoelectronic, and magnetic properties—properties that cannot be achieved by any single component alone.

[0004] Therefore, how to provide a 4D printing polymer composite material with light-controlled modulus transformation and its preparation method has become the focus of current research. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a 4D-printed polymer composite material with light-controlled modulus transformation and its preparation method. This invention has stable and excellent photothermal properties, can print high-precision structures through DLP 4D printing, and utilizes near-infrared laser (NIR) to achieve precise control of the modulus transformation of the printed structure.

[0006] To achieve the aforementioned inventive objectives, the present invention employs the following technical solution:

[0007] A photosensitive modulus-transformation 4D printing polymer composite material, comprising an ATHP resin solution and photothermal nanomaterial WO3. 3-x Two components, one of which is photothermal nanomaterial WO 3-x It accounts for 0.8 to 2.2 wt.‰ of the total weight of the ATHP resin solution.

[0008] A method for preparing a 4D-printed polymer composite material with light-controlled modulus transformation, wherein the preparation method involves mixing an ATHP resin solution with photothermal nanomaterial WO3. 3-x The process of obtaining a nanocomposite polymer system (ATHP NC system) involves the following steps:

[0009] Step 1: Preparation of photothermal nanomaterial WO 3-x :

[0010] The photothermal nanomaterial WO3 was obtained by using a mixture of tungsten chloride, acetic acid, and ultrapure water as reactants via a hydrothermal reaction. 3-x ;

[0011] Step 2: Prepare ATHP resin solution:

[0012] First, a photocurable resin is prepared by mixing acrylic monomers. Then, a photothermal dual-curable resin is prepared by mixing acrylic monomers with isocyanate groups. After mixing the photocurable resin and the photothermal dual-curable resin and stirring for 8-12 minutes, an ATHP resin solution is obtained.

[0013] Step 3: Preparation of ATHP NC material:

[0014] The ATHP resin solution prepared in step 2 and the photothermal nanomaterial WO obtained in step 1 are combined. 3-x The composite material was prepared by mixing the components in a specified ratio.

[0015] Step 4, DLP printing:

[0016] The structure was printed at room temperature using a DLP printer. Based on the curing characteristics of the ATHP NC material, the appropriate slice thickness and exposure time were selected. After printing, the surface of the obtained three-dimensional structure was cleaned with anhydrous ethanol to remove the incompletely cured parts.

[0017] Step 5: Photothermal and mechanical property transformation tests of ATHP NC materials:

[0018] The structural samples printed by the DLP printer were irradiated with NIR, and the temperature changes at the irradiated points were observed in real time using a near-infrared camera to test their photothermal properties. The test samples of the mechanical properties of the ATHP NC material were placed in an electric heating oven to ensure that the material reacts completely at different curing stages, so as to ensure the reliability of the test data.

[0019] The method for preparing 4D printed polymer composite materials with light-controlled modulus transformation includes step 1, in which photothermal nanomaterial WO3 is prepared. 3-x First, 150–260 mg of tungsten chloride (WCl6) is dissolved in 80–120 mL of ethanol (EtOH) in an Erlenmeyer flask. After the tungsten chloride (WCl6) is completely dissolved, 1–3 mL of acetic acid and 4–8 mL of ultrapure water (DI water) are added to the Erlenmeyer flask, and stirring is continued for 1–3 minutes. Then, 80–100 mL of the solution is poured into the lining of a high-temperature reactor. The reactor is then tightened and placed in an electric heating blast oven. The temperature of the blast oven is set to 100–150 °C, and the reactor is heated for 7–10 hours. After that, the reactor is cooled to room temperature along with the blast oven. Then, it is removed from the oven, and the supernatant in the reactor is discarded, leaving the nanoparticles at the bottom. The nanoparticles are washed with ethanol (EtOH) 2–4 times. Finally, the obtained nanoparticles are dried at 30–40 °C for 6–10 hours for later use.

[0020] The method for preparing the light-controlled modulus transformation 4D printing polymer composite material, wherein in step 2, when preparing the photocurable resin, 25-35g of aliphatic polyurethane diacrylate (AUD) is used as a crosslinking agent, 15-25g of isobornyl acrylate (IBOA) and 45-55g of benzyl acrylate (BA) are used as reactant monomers, and 0.8-1.2g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) is used as a photoinitiator.

[0021] In the method for preparing the light-controlled modulus transformation 4D printing polymer composite material, in step 2, when preparing the photothermal dual-curing resin, 1.2–1.5 g of TDI-HPA (TDI-HPA is an addition product of toluene diisocyanate (TDI) and hydroxypropyl acrylate (HPA), 0.6–0.8 g of 1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione (1,3,5-Tris(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione, HDI) and 0.12–0.3 g of polyethylene glycol (PEG400) are mixed.

[0022] The method for preparing 4D printed polymer composite materials with light-controlled modulus transformation, wherein in step 3, when preparing the ATHP NC material, the prepared photothermal nanomaterial WO is used. 3-x The nanocomposite system (ATHP NC) can be obtained by mixing with ATHP resin solution. The mixing process requires mechanical stirring for 15–25 minutes followed by ultrasonic dispersion for 15–25 minutes to ensure the stability of the photothermal nanomaterials. 3-x WO photothermal nanomaterials can be uniformly dispersed in ATHP resin solution. 3-x The net content in the ATHP resin solution is 0.8–2.2 wt.‰.

[0023] The method for preparing the 4D printed polymer composite material with light-controlled modulus transformation includes step 4, in which the DLP printer is used to print the structure at room temperature, the thickness of each layer is set to 90-110 μm, and the exposure time is from 1.1 s to 2.0 s. After printing, the surface of the obtained three-dimensional structure is cleaned with anhydrous ethanol to remove incompletely cured parts. Finally, the printed structure is post-cured in an ultraviolet curing chamber for 25-35 min. After ultraviolet post-curing, the printed structure is placed in an electric heating oven and heated and cured at 85-95℃ and 190-210℃ respectively, for curing times of 2-4 h and 0.5-1.5 h respectively.

[0024] In the method for preparing the 4D printed polymer composite material with light-controlled modulus transformation, in step 5, when testing the photothermal and mechanical property transformation of the ATHP NC material, the structural sample printed by the DLP printer is obtained by UV curing the ATHP NC material for 4-6 minutes to obtain the corresponding test sample.

[0025] In the method for preparing the 4D printing polymer composite material with light-controlled modulus transformation, in step 5, when testing the mechanical property transformation of the ATHP NC material, the test samples for the mechanical properties of the ATHP NC material are obtained by UV curing the ATHP NC system for different times in a UV curing chamber, namely 180s, 240s and 300s. After curing, corresponding standard tensile samples are obtained. Then, the UV-cured samples are subjected to thermocuring at temperatures of 90℃ and 200℃ for different times.

[0026] The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation, wherein the ultraviolet curing chamber is manufactured by Formlabs, USA, with a wavelength of 365nm and a light intensity of 7mW / cm². -2 .

[0027] By employing the technical solution described above, the present invention has the following advantages:

[0028] This invention addresses the challenges of precisely controlling structural modulus and lacking functionality in 4D printed structures by incorporating photothermal nanomaterials (WO3) into the ATHP system. 3-x NIR was used to achieve precise control of the modulus of the printed structure, among which the micro-photothermal nanomaterial WO 3-x The presence of ATHP NC facilitates the realization of controllable photothermal properties in printed nanocomposite materials. Therefore, the ATHP NC system can achieve arbitrary combinations of soft and hard regions in the printed structure under NIR radiation. Compared with multi-material printing, this invention reduces the cumbersome steps of changing printing materials and avoids interface bonding problems that may occur during printing. Furthermore, the material preparation process described in this invention is simple, the reaction is controllable and can be industrialized, and the cost is low. Moreover, in-situ adjustment of the sensitivity of flexible sensors and in-situ reinforcement of finger sensor microstructures can be achieved simply through NIR radiation. The ATHP NC material system proposed in this invention provides rich mechanical property diversity for DLP4D printed structures, broadens the design space of printed devices, and is suitable for widespread promotion and application. Attached Figure Description

[0029] Figure 1 The photothermal nanomaterial WO in the embodiments of the present invention 3-x Stability demonstration in the ATHP system;

[0030] Figure 2 ATHP and photothermal nanomaterial WO are examples of the embodiments of the present invention. 3-x (2wt.‰) SEM images and EDS elemental scans of the cross-section of the sample after composite preparation;

[0031] Figure 3The ATHP NC system and photothermal nanomaterial WO in the embodiments of the present invention 3-x Viscosity test before and after mixing (2wt.‰);

[0032] Figure 4 Different photothermal nanomaterials WO in the embodiments of the present invention 3-x The temperature and penetration depth that nanocomposite samples with composite concentrations (0.8–1.4 wt.‰) can reach within 15 seconds under NIR irradiation of different intensities (arrows indicate the direction of thermal radiation).

[0033] Figure 5 Different photothermal nanomaterials WO in the embodiments of the present invention 3-x The temperature and penetration depth that nanocomposite samples with composite concentrations (1.6–2 wt.‰) can reach within 15 seconds under NIR irradiation of different intensities (arrows indicate the direction of thermal radiation).

[0034] Figure 6 This is a stress-strain test of the ATHP and ATHP NC systems after UV curing in the embodiments of the present invention;

[0035] Figure 7 This is a stress-strain test of the ATHP and ATHP NC systems after curing at 90°C in the embodiments of the present invention;

[0036] Figure 8 This is a stress-strain test of the ATHP and ATHP NC systems after curing at 200°C in the embodiments of the present invention;

[0037] Figure 9 Design and printing of the intelligent motion sensor in this embodiment of the invention: (a) macroscopic photograph and SEM image of the finger sensor structure; (b) NIR “reinforced” structural connection and corresponding bending ΔR / R0 response; all scales are 10mm. Detailed Implementation

[0038] The present invention can be explained in more detail through the following embodiments, but the present invention is not limited to the following embodiments;

[0039] This invention addresses the problems of precise control over the modulus transformation and lack of functionality in current photopolymer 4D printing structures. The invention addresses these issues by incorporating photothermal nanomaterials (WO3) into the ATHP system. 3-x The method described above prepared composite materials whose printed structural modulus could be precisely controlled via NIR. Among them, the micro-photothermal nanomaterial WO3... 3-xThe presence of (2wt.‰) facilitates the controllable photothermal properties of printed nanocomposite materials. Therefore, the ATHP NC system can achieve arbitrary combinations of soft and hard regions in the printed structure under NIR irradiation, avoiding interface bonding problems that may arise during multi-material printing. Furthermore, the application demonstrations of tensile sensor and finger motion sensor structures formed by DLP4D printing technology using the ATHP NC system show that NIR photocontrol technology can achieve in-situ adjustment of the sensitivity of flexible sensors and in-situ reinforcement of the finger sensor microstructure. The ATHP NC system proposed in this invention offers a rich diversity of mechanical properties, greatly expanding the design space of DLP4D printed devices.

[0040] Combined with appendix Figures 1-9 The present invention discloses a 4D printing polymer composite material with light-controlled modulus transformation, wherein the 4D printing polymer composite material comprises ATHP resin solution and photothermal nanomaterial WO3. 3-x Two components, one of which is photothermal nanomaterial WO 3-x The amount of photothermal nanomaterial WO3 accounts for 0.8–2.2 wt.‰ of the total weight of the ATHP resin solution. During implementation, the photothermal nanomaterial WO3... 3-x The preferred percentage by weight of the ATHP resin solution is 2 wt.‰.

[0041] A method for preparing a 4D-printed polymer composite material with light-controlled modulus transformation, wherein the preparation method involves mixing an ATHP resin solution with photothermal nanomaterial WO3. 3-x The process of obtaining a nanocomposite polymer system (ATHP NC system) involves the following steps:

[0042] Step 1: Preparation of photothermal nanomaterial WO 3-x :

[0043] The photothermal nanomaterial WO3 was obtained by using a mixture of tungsten chloride, acetic acid, and ultrapure water as reactants via a hydrothermal reaction. 3-x ;

[0044] During implementation, photothermal nanomaterial WO3 is prepared. 3-xFirst, 150–260 mg of tungsten chloride (WCl6) is dissolved in 80–120 mL of ethanol (EtOH) in an Erlenmeyer flask. After the tungsten chloride (WCl6) is completely dissolved, 1–3 mL of acetic acid and 4–8 mL of ultrapure water (DI water) are added to the Erlenmeyer flask. The mixture is stirred for 1–3 minutes. Then, 80–100 mL of the solution is poured into the lining of a high-temperature reactor. The reactor is then tightened and placed in an electric heating blast oven. The temperature of the blast oven is set to 100–150 °C. After heating for 7–10 hours, the reactor is cooled to room temperature along with the blast oven. The reactor is then removed from the oven, and the supernatant in the reactor is discarded, leaving the nanoparticles at the bottom. The nanoparticles are washed with ethanol (EtOH) 2–4 times. Finally, the obtained nanoparticles are dried at 30–40 °C for 6–10 hours for later use.

[0045] Step 2: Prepare ATHP resin solution:

[0046] First, a photocurable resin is prepared by mixing acrylic monomers. Then, a photothermal dual-curable resin is prepared by mixing acrylic monomers with isocyanate groups. After mixing the photocurable resin and the photothermal dual-curable resin and stirring for 8-12 minutes, an ATHP resin solution is obtained.

[0047] In practice, when preparing the photocurable resin, 25-35g of aliphatic polyurethane diacrylate (AUD) is used as a crosslinking agent, 15-25g of isobornyl acrylate (IBOA) and 45-55g of benzyl acrylate (BA) are used as reactant monomers, and 0.8-1.2g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) is used as a photoinitiator.

[0048] Furthermore, in preparing the photothermal dual-curing resin, 1.2–1.5 g of TDI-HPA (TDI-HPA is the addition product of toluene diisocyanate (TDI) and hydroxypropyl acrylate (HPA), used in this invention to achieve ATHP) is used. The secondary and tertiary curing of the NC system mainly involves combining with monomers such as polyethylene glycol (PEG400) and 1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione (HDI) to generate polyurethane-polyacrylate composite materials with physical and chemical crosslinking effects. This involves mixing 0.6–0.8 g of 1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione (HDI) and 0.12–0.3 g of polyethylene glycol (PEG400).

[0049] Step 3: Preparation of ATHP NC material:

[0050] The ATHP resin solution prepared in step 2 and the photothermal nanomaterial WO obtained in step 1 are combined. 3-x The composite material was prepared by mixing the components in a specified ratio.

[0051] During implementation, when preparing ATHP NC materials, the prepared photothermal nanomaterial WO 3-x The nanocomposite system (ATHP NC) can be obtained by mixing with ATHP resin solution. The mixing process requires mechanical stirring for 15–25 minutes followed by ultrasonic dispersion for 15–25 minutes to ensure the stability of the photothermal nanomaterials. 3-x WO photothermal nanomaterials can be uniformly dispersed in ATHP resin solution. 3-x The net content in the ATHP resin solution is 0.8–2.2 wt.‰. In specific applications, the photothermal nanomaterial WO... 3-x The preferred net content in the ATHP resin solution is 2 wt.‰;

[0052] Step 4, DLP printing:

[0053] The structure was printed at room temperature using a DLP printer. Based on the curing characteristics of the ATHP NC material, the appropriate slice thickness and exposure time were selected. After printing, the surface of the obtained three-dimensional structure was cleaned with anhydrous ethanol to remove the incompletely cured parts.

[0054] During implementation, the DLP printer was used to print the structure at room temperature, with each layer thickness set to 90–110 μm and an exposure time of 1.1–2.0 s. After printing, the surface of the obtained three-dimensional structure was cleaned with anhydrous ethanol to remove any incompletely cured parts. Finally, the printed structure was post-cured in a UV curing chamber for 25–35 min. After UV post-curing, the printed structure was placed in an electric heating oven and heated to cure at 85–95 °C and 190–210 °C, respectively, for 2–4 h and 0.5–1.5 h, respectively.

[0055] In practical implementation, a DLP 3D printer can be selected as the DLP printer. DLP stands for Digital Light Processing, which is a photopolymer 3D printing technology. The corresponding equipment can be purchased directly from the market. When 4D printing is required, a response stimulus process can be added to the 3D printing process. That is, 4D printing adds a time dimension to 3D printing. This is common knowledge technology in this field.

[0056] Step 5: Photothermal and mechanical property transformation tests of ATHP NC materials:

[0057] The structural samples printed by the DLP printer were irradiated with NIR, and the temperature changes at the irradiated points were observed in real time using a near-infrared camera to test their photothermal properties. The test samples of the mechanical properties of the ATHP NC material were placed in an electric heating oven to ensure that the material reacts completely at different curing stages, so as to ensure the reliability of the test data.

[0058] During implementation, when testing the photothermal and mechanical property transformation of ATHP NC material, the structural sample printed by the DLP printer was a UV-cured ATHP NC material with a curing time of 4 to 6 minutes, resulting in the corresponding test sample.

[0059] Furthermore, during the mechanical property transformation test of ATHP NC material, the test samples of ATHP NC material were obtained by UV curing the ATHP NC system for different times in a UV curing oven, namely 180s, 240s and 300s. After curing, the corresponding standard tensile samples were obtained. Then, the UV-cured samples were subjected to heat curing at temperatures of 90℃ and 200℃ for different times.

[0060] Furthermore, in the method for preparing the light-controlled modulus transformation 4D printing polymer composite material, the ultraviolet curing chamber is manufactured by Formlabs, USA, with a wavelength of 365nm and a light intensity of 7mW / cm². -2 .

[0061] In practical applications, the specific implementation methods of each step of this invention are as follows:

[0062] Step 1, Photothermal Nanomaterials WO 3-x During the preparation of WO3 photothermal nanomaterials, the following steps are taken: 3-x The reagent components and specific contents are shown in Table 1. In a typical synthesis procedure, WCl6 (200 mg) was first dissolved in 100 mL of ethanol in an Erlenmeyer flask. After the WCl6 was completely dissolved, 2 mL of acetic acid and 6 mL of ultrapure water were added to the Erlenmeyer flask, and stirring was continued for 1 min. Then, 90 mL of the solution was poured into the lining of a 100 mL high-temperature reactor. The reactor was then tightened and placed in an electric heating blast oven. The temperature of the blast oven was set to 120 °C (reaction temperature). After heating for a certain period of time, the reactor was cooled to room temperature along with the blast oven. Then, it was removed from the oven, the supernatant in the reactor was discarded, and the nanoparticles at the bottom were left. The nanoparticles were washed three times with ethanol. Finally, the obtained nanoparticles were dried at 35 °C for 8 h for later use.

[0063] Table 1: Additions to photothermal nanomaterials WO 3-x Dosage of each component in the solution

[0064]

[0065] Step 2, Preparation of ATHP Resin Solution: The ATHP resin solution consists of two parts: one part is a photocurable resin (1.73g, Table 2); the photocurable resin part is prepared by mixing aliphatic polyurethane diacrylate (AUD) as a crosslinking agent, isobornyl acrylate (IBOA) and benzyl acrylate (BA) as reactant monomers, and diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as a photoinitiator. The other part is a photothermal dual-curing resin, which is a mixture of TDI-HPA, 1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazine-2,4,6-trione (HDI), and polyethylene glycol (PEG400) (Table 3, SMP2). The photocurable resin is mixed with SMP1 (1.73 g) and the photothermal dual-curing SMP2, and stirred for 10 min to obtain the ATHP resin solution. To prepare the relevant test samples, the solution is poured into a Teflon mold, covered with a layer of transparent glass, and cured in a UV curing chamber (Formlabs, USA, wavelength 365 nm, light intensity 7 mW / cm²). -2 The sample was irradiated for 5 minutes to obtain a UV-cured sample. The sample was then heated at 90℃ and 200℃ for 180 minutes and 60 minutes respectively to ensure that the system reacted fully in each stage of the three-stage curing process.

[0066] Table 2: Composition Ratio of Photocurable SMP1

[0067]

[0068] Table 3: Distribution ratio of each group in photothermal dual-curing SMP2

[0069]

[0070] Step 3, during the preparation and dispersibility testing of ATHP NC materials, the prepared photothermal nanomaterial WO... 3-x The nanocomposite system (ATHP NC) can be obtained by mixing with the ATHP system. The two should be mechanically stirred for 20 minutes first, followed by ultrasonic dispersion for about 20 minutes to ensure the WO content of the photothermal nanomaterials. 3-x It can be uniformly dispersed in the ATHP system. Photothermal nanomaterials WO 3-xThe net contents in the ATHP NC system were 0.8 wt.‰, 1.0 wt.‰, 1.2 wt.‰, 1.4 wt.‰, 1.6 wt.‰, 1.8 wt.‰, and 2.0 wt.‰, respectively. Figure 1 As shown, in all ATHP NC precursor solutions, the photothermal nanomaterial WO 3-x The stable dispersion time exceeded 60 minutes, and no obvious macroscopic precipitation was observed during the test, demonstrating excellent dispersion stability. Figure 2 As shown, considering that the higher the concentration of nanoparticles, the greater the possibility of aggregation and sedimentation, we did not continue to increase the composite concentration of nanoparticles, and preferentially selected 2.0 wt.‰ of the photothermal nanomaterial WO3. 3-x The composite concentration was used as the experimental composite concentration and energy dispersive spectroscopy (EDS) was performed. The test results showed that the photothermal nanomaterial WO 3-x It is uniformly dispersed in the polymer matrix.

[0071] Step 4, during DLP printing, such as Figure 3 As shown, the test results show that the maximum viscosity of the ATHP NC system is only 740 mPa·s. According to literature reports, resin solutions with a viscosity higher than 3 Pa·s are not suitable for DLP 3D printing. Therefore, the ATHP NC system is suitable for DLP 4D printing.

[0072] The structure was printed at room temperature using a DLP 3D printer (405nm, 19.85mWcm). -2 The thickness of each layer was set to 100 μm, and the exposure time varied from 1.1 s to 2.0 s. After printing, the surface of the obtained three-dimensional structure was cleaned with anhydrous ethanol to remove any incompletely cured parts. Finally, the printed structure was post-cured in a UV curing chamber for 30 minutes. After UV post-curing, the printed structure was placed in an electric heating oven and cured at 90℃ and 120℃ respectively, for 3 hours and 1 hour respectively.

[0073] Step 5: When testing the photothermal properties of ATHP NC material, the ATHP NC material is first subjected to UV curing (curing time is 5 min) to obtain the corresponding test sample. The sample contains the photothermal nanomaterial WO3. 3-x The net contents were 0.8wt.‰, 1.0wt.‰, 1.2wt.‰, 1.4wt.‰, 1.6wt.‰, 1.8wt.‰, and 2.0wt.‰, respectively. The test sample size was 15mm × 8mm (diameter × thickness). The power of the 808nm NIR (MDL-N-808-10W, Changchun New Industries Optoelectronics Technology Co., Ltd.) was set to 10Wcm. -2 12Wcm -2 14Wcm -216Wcm -2 and 18Wcm -2 The radiation time was uniformly set to 15 seconds. The radiation point was selected at the edge of the test sample to facilitate observation and imaging of the test sample using an infrared camera. The radiation range in the XY and Z directions after being irradiated by NIR was then used to determine the accuracy of NIR radiation on the ATHP NC sample.

[0074] Specific test data such as Figure 4 , Figure 5 As shown, all test data are derived from top and side views of the real-time temperature of the test samples taken by a near-infrared camera (FOTRIC, 323Q, Shanghai Thermal Imaging Technology Co., Ltd.). Figure 4 , Figure 5 The infrared imaging data shown in the image was processed using specialized software (AnalyzIR) to obtain the WO3 of different photothermal nanomaterials. 3-x Real-time temperature changes in the XY and Z directions of ATHP NC samples under the same irradiation time and with different NIR radiation intensities and composite concentrations. Strictly fixed infrared camera and different photothermal nanomaterials (WO3) were required during the experiment. 3-x The relative positions of the test samples with composite concentrations and the NIR laser are used to reduce experimental errors and ensure rigorous comparability of near-infrared data from different test samples.

[0075] like Figure 4 , Figure 5 As shown in the top view of the infrared thermal image of the test sample, it can be seen that within a 15s radiation time, the photothermal nanomaterial WO in the nanocomposite sample... 3-x With the gradual increase of recombination concentration and NIR power, the highest temperature achievable at the radiation point increased from 72.7℃ to 268.5℃ (NIR power increased from 10W / cm²). -2 Increased to 18Wcm -2 Furthermore, it can be seen that the NIR radiation accuracy in the XY direction remains around 2 mm. Additionally, the side view of the infrared thermal image of the test sample clearly shows that the photothermal nanomaterial WO... 3-x Net content is 0.8 wt.‰, NIR power is 18 W / cm². -2 Under these conditions, the temperature at the top radiation point of the test sample was 76.7℃, while the temperature at the bottom was 55.1℃, a difference of only 21.6℃ between the top and bottom of the radiation point. However, in the photothermal nanomaterial WO... 3-x The net content increased to 2 wt.‰, and the NIR power was 18 W / cm². -2Under these conditions, the temperature at the top of the radiation point of the test sample can rise to 261.6℃, while the temperature at the bottom is only 51.1℃, with a temperature difference of 210.5℃ between the top and bottom of the radiation point. This result indicates that, under constant NIR power, the photothermal nanomaterial WO 3-x The increased net content ensures a rapid rise in the radiation point temperature while effectively reducing the penetration depth of NIR, which is highly advantageous for using NIR to precisely control the local modulus transformation of ATHP NC samples. Furthermore, the side view of the infrared thermographic image of the test sample shows that the NIR radiation accuracy in the Z direction remains around 2 mm. The radiation accuracy mentioned above refers to the NIR radiation range after the radiation point reaches the target reaction temperature.

[0076] Based on the above test results of the temperature radiation accuracy of the NIR-controlled nanocomposite system, the following conclusions can be drawn: The photothermal nanomaterial WO 3-x In the nanocomposite system, not only did it exhibit excellent photothermal properties, but it also showed promising potential applications in precisely controlling the temperature of the ATHP NC system using NIR to achieve precise control of the structural modulus.

[0077] Furthermore, during the mechanical property transformation test of ATHP NC materials, the mechanical property test was conducted using a universal tensile testing machine (2kN, Instron 3344) at a speed of 10.0 mm / min. -1 The tensile test was conducted at a specific speed. The Young's modulus (E) of the specimen was calculated based on the Hooke's zone of the tensile curve. All test specimens were 12 mm × 2 mm × 1 mm in size (the length of the tensile portion was 10 mm). The ATHP NC system was cured using a UV curing oven for different times: 180 s, 240 s, and 300 s. After curing, corresponding standard tensile specimens were obtained. These UV-cured specimens were then subjected to thermosetting at 90 °C and 200 °C for different times. To ensure the accuracy of the experimental results, three tensile tests were performed on each prepared tensile specimen under each experimental condition.

[0078] like Figure 6 As shown, processing the stress-strain curves reveals the modulus and tensile strain of the ATHP NC system. It can be seen that the strain of the ATHP NC system after UV curing reaches approximately 172%, and the modulus is approximately 2.34 MPa. Figure 7 As shown, under reaction conditions of 90℃, the tensile test results indicate that with the extension of heating time, the strain of the sample gradually decreases from 172% to approximately 88%, while the corresponding modulus gradually increases from 2.34 MPa to approximately 158.12 MPa. Figure 8As shown, under high-temperature reaction conditions of 200℃, the heating times of the test samples were set to 0.5, 1, 1.5, 2, and 2.5 h, respectively. The tensile test results show that as the heating time increased, the strain of the sample gradually decreased from 88% to approximately 52%, but the corresponding modulus increased sharply from 158.12 MPa to approximately 1242.46 MPa. Compared to the uncomposite photothermal nanomaterial WO4, this represents a significant increase. 3-x The polymer matrix has similar mechanical properties, indicating that the photothermal nanomaterial WO 3-x The composite did not have a significant impact on the polymer matrix.

[0079] The applications of the ATHP NC material sensor prepared by this invention are shown below:

[0080] Based on the mechanical property test results in step 5, DLP4D printing using ATHP NC material has advantages in manufacturing custom sensors, which enables the further fabrication of wearable electronic devices for smart monitoring. Figure 9 This demonstrates a DLP-printed finger motion sensor for human-machine interfaces using ATHP NC material. To increase friction, spherical protrusions with slightly curved tops are printed on the inner surface of the sensor. Additionally, NIR radiation connection points reinforce the connection between the ring and the sensor body. It can be seen that only 3 minutes of radiation is required to maintain a stable connection during large deformations, enhancing the sensor's operational stability. Furthermore, it can be observed that the resistance changes during finger flexion, enabling real-time monitoring of finger movement. Similar sensors can be easily designed to suit different users or joints. In summary, this example showcases the potential applications of ATHP NC in smart sensors. The resistance data demonstrated in this application uses a Keithley 2450 digital source meter. During testing, a tight connection between the sample, leads, and digital source meter must be maintained.

[0081] The parts of this invention not described in detail are prior art.

[0082] The embodiments selected herein for the purpose of disclosing the inventive objectives are currently considered suitable; however, it should be understood that the invention is intended to include all variations and modifications of the embodiments that fall within the scope of this concept and invention.

Claims

1. A method for preparing a 4D printing polymer composite material with light-controllable modulus transition, characterized by comprising the following steps: Step 1, preparing a light-cured resin: first, preparing the light-cured resin using a mixture of acrylic monomers; then, preparing a light-heat dual-cured resin using a mixture of acrylic monomers with isocyanate groups; and then, mixing the light-cured resin and the light-heat dual-cured resin, stirring for 8-12 min to obtain the ATHP resin solution; Step 2, preparing the ATHP NC material: Step 3, DLP printing: printing a structure at room temperature using a DLP printer, selecting a suitable slice thickness and exposure time according to the curing characteristics of the ATHP NC material, and then cleaning the surface of the obtained three-dimensional structure with anhydrous ethanol to remove the incompletely cured parts; Step 4, testing the light-heat performance and mechanical performance transition of the ATHP NC material: irradiating the structure sample printed by the DLP printer using NIR, and observing the temperature change of the irradiated point in real time using a near-infrared camera to test the light-heat performance of the ATHP NC material, and placing the test sample of the mechanical performance of the ATHP NC material into an electric heating air oven to heat, so as to ensure that the material is fully reacted at different curing stages and to ensure the reliability of the test data. The 4D printing polymer composite comprises an ATHP resin solution and a photo-thermal nanomaterial WO 3-x Two components, wherein the photo-thermal nanomaterial WO 3-x 0.8-2.2 wt.‰, based on the total weight of the ATHP resin solution; The preparation method is to obtain a nanocomposite polymer system by compounding an ATHP resin solution with a photothermal nanomaterial WO 3-x The composite is obtained by compounding an ATHP resin solution with a photothermal nanomaterial WO 3-x The composite is obtained by compounding an ATHP resin solution with a photothermal nanomaterial WO 3-x The composite is obtained by Step 1, Preparation of photothermal nanomaterials WO 3-x : The photo-thermal nanomaterial WO is obtained by hydrothermal reaction using tungsten chloride, acetic acid and ultrapure water as reactants 3-x ; In the step 2, when preparing the light-cured resin, 25-35 g of aliphatic polyurethane diacrylate is used as a crosslinking agent, 15-25 g of isobornyl acrylate and 45-55 g of benzyl acrylate are used as reaction monomers, and 0.8-1.2 g of diphenyl phosphine oxide is used as a photoinitiator. In the step 4, when printing using the DLP printer, the DLP printer is used to print a structure at room temperature, the thickness of each layer is set to 90-110 mm, the exposure time is 1.1 s-2.0 s, after printing, the surface of the obtained three-dimensional structure is cleaned with anhydrous ethanol to remove the incompletely cured parts, and finally, the printed structure is subjected to post-curing in a ultraviolet curing oven for 25-35 min, and then the printed structure is placed into an electric heating air oven and heated at 85-95℃ and 190-210℃, respectively, for 2-4 h and 0.5-1.5 h, respectively. In the step 5, when testing the light-heat performance and mechanical performance transition of the ATHP NC material, the structure sample printed by the DLP printer is subjected to ultraviolet curing, and the curing time is 4-6 min to obtain the corresponding test sample. ​ The ATHP resin solution prepared in step 2 and the photo-thermal nanomaterial WO 3-x The composite material was prepared by mixing in proportion; ​ ​ ​ ​ 2. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 1, characterized in that: The step 1 in preparation of photo-thermal nanomaterials WO 3-x When, first in the conical flask 150-260 mg of tungsten chloride is dissolved in 80-120 mL of ethanol, after tungsten chloride is completely dissolved, 1-3 mL of acetic acid and 4-8 mL of ultrapure water is added to the conical flask, continue to stir 1-3 min, then 80-100 mL of solution is poured into the high temperature reaction kettle lining, immediately the reaction kettle is tightened and put into the electric heating oven, the temperature of the oven is set to 100-150℃, after heating for 7-10 h, the reaction kettle is cooled to room temperature with the oven, then it is taken out of the oven, the supernatant in the reaction kettle is poured off, the nanoparticles at the bottom are left, the nanoparticles are washed with ethanol for 2-4 times, finally the obtained nanoparticles are dried at a temperature of 30-40℃ for 6-10 h and ready for use.

3. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 1, characterized in that: ​ 4. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 1, characterized in that: In step 3, when preparing the ATHP NC material, the prepared photothermal nanomaterial WO 3-x The nanocomposite system can be obtained by mixing with ATHP resin solution. The mixture should first be mechanically stirred for 15–25 minutes, followed by ultrasonic dispersion for 15–25 minutes to ensure the WO3 content of the photothermal nanomaterials. 3-x WO photothermal nanomaterials can be uniformly dispersed in ATHP resin solution. 3-x The net content in the ATHP resin solution is 0.8–2.2 wt.‰.

5. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 1, characterized in that: ​ 6. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 1, characterized in that: ​ 7. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 1, characterized in that: In the mechanical property transformation test of the ATHP NC material in step 5, the test sample of the mechanical property of the ATHP NC material is obtained by ultraviolet curing of the ATHP NC system in an ultraviolet curing box for different times, i.e. 180 s, 240 s and 300 s, and the corresponding standard tensile sample is obtained after curing, and then the sample after ultraviolet curing is subjected to heat curing at 90 DEG C and 200 DEG C for different times.

8. The method for preparing the 4D printing polymer composite material with light-controlled modulus transformation according to claim 7, characterized in that: The wavelength of the UV curing box is 365 nm, and the light intensity is 7 mWcm -2 .

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