Sustainable intelligent plastic with shape memory and light management functions and preparation method and application thereof

Abstract

The invention discloses sustainable intelligent plastic with shape memory and light management functions and a preparation method and application thereof, and belongs to the technical field of intelligent high polymer materials, the sustainable intelligent plastic is formed by self-assembly of montmorillonite, gelatin and tannic acid through vacuum filtration, and a composite film with an ordered layered structure is formed. The sustainable intelligent plastic provided by the invention has the characteristic of converting ultraviolet light into visible light. Through integration of the characteristics, the sustainable intelligent plastic with the shape memory and light management functions prepared by the invention is particularly suitable for constructing an agricultural greenhouse intelligent actuator, can automatically adjust illumination uniformity according to weather (sunny / rainy days) and promote photosynthesis of plants, and meanwhile, the material can be quickly biodegraded in a natural environment, so that the plastic is environment-friendly and pollution-free. And the method has obvious sustainability and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of intelligent polymer materials technology, and in particular relates to a sustainable intelligent plastic with shape memory and light management functions, its preparation method and application. Background Technology

[0002] Plastics are inexpensive, lightweight, and durable materials that play a vital role in societal development. Among all types of plastics, functional plastics with reversible light management are particularly popular because they can be easily processed and molded into a variety of products for use in agriculture, industry, solar energy, and environmental science. Currently, most of these functional plastics are derived from gasoline and cannot be biodegradable, posing a significant threat to the environment.

[0003] Researchers are increasingly focusing on producing biodegradable and sustainable plastics from renewable resources, such as woody components (cellulose, hemicellulose, and lignin), marine polymers (chitin, chitosan), starch, proteins, gelatin, DNA, and carbon dioxide. In addition to sustainable sources, there is also an emphasis on developing energy-efficient and environmentally friendly processing methods. In recent years, researchers have reported a hydrogenation-curing method for cellulose-based plastics. These plastics can be molded with the aid of water, without the need for heating or other energy-intensive methods, representing a future trend. Nevertheless, bioplastics from sustainable sources processed in a green manner still lack reversible light management properties. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a sustainable smart plastic with shape memory and light management functions, along with its preparation method and applications. This invention utilizes a supramolecular composite of montmorillonite (MMT), gelatin, and tannic acid (TA) to synergistically integrate mechanical reinforcement and dynamic optical management properties into a single bioplastic. This provides a high-performance smart bioplastic with integrated reversible optical control, capable of converting harmful or poorly utilized ultraviolet light into visible light beneficial for photosynthesis, thereby comprehensively improving photosynthetic efficiency and addressing the urgent need for adaptive, multifunctional materials in modern agriculture and other fields.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a sustainable smart plastic with shape memory and light management functions, which is prepared by self-assembly of montmorillonite, gelatin and tannic acid through vacuum filtration.

[0006] Furthermore, the sustainable smart plastic has an ordered layered structure.

[0007] Secondly, the present invention provides a method for preparing the above-mentioned sustainable smart plastic with shape memory and light management functions, comprising the following steps: mixing montmorillonite suspension and gelatin aqueous solution to obtain a composite solution, vacuum filtering the composite solution to form a gel film on the filter membrane, then pouring in tannic acid aqueous solution and supplementing with vacuum filtration, drying and peeling to prepare the sustainable smart plastic with shape memory and light management functions.

[0008] In this invention, montmorillonite is used as a nanofiller to improve the mechanical properties of bioplastics. Gelatin exhibits solubility and switchable "clear-haze" properties, attributed to its variable β-sheet content in organic and aqueous solutions. The supramolecular interactions between tannic acid and gelatin are altered in aqueous and organic solvents, giving the bioplastics clear processability. These reversible photosensitivity and solvent-based processing properties, coupled with inherent fluorescence, make bioplastics intelligent light-conversion actuators that facilitate natural photosynthesis.

[0009] Further, the concentration of the montmorillonite suspension is 1 wt.%; the concentration of the gelatin aqueous solution is 0.5%; the mass concentration of the tannic acid aqueous solution is 0.04%; and the volume ratio of the montmorillonite suspension, gelatin aqueous solution, and tannic acid aqueous solution is 1:1:2.

[0010] Gelatin serves as both the matrix and framework. Gelatin molecules unfurl in water, forming a three-dimensional network through hydrogen bonds and hydrophobic interactions, providing the basis for flexibility and shape memory. Excessive gelatin leads to excessively high system viscosity and dilutes the effective concentration of the reinforcing phase (MMT) and crosslinking agent (TA). This results in a relative insufficiency of the reinforcing MMT sheets and the strong crosslinking TA per unit volume, leading to a softer material with lower strength, reduced modulus, slow drying, and a tendency to wrinkle.

[0011] Montmorillonite is a reinforcing filler used to provide physical crosslinking points. MMT consists of nanoscale sheets with extremely high specific surface area and rigidity. It can interact with gelatin molecules, significantly improving the material's mechanical strength, thermal stability, and barrier properties. Simultaneously, its sheet structure hinders molecular chain slippage, assisting in shape fixation. Excessive MMT can disrupt the network structure of the gelatin continuous phase. Nanosheets are prone to aggregation, forming stress concentration points, leading to brittle, easily fractured materials with poor film-forming properties and interfacial aggregation.

[0012] Tannic acid is a highly efficient chemical crosslinking agent, but excessive TA can cause two problems: first, the crosslinking is too high; second, TA itself, as a small molecule, may have a plasticizing or destructive effect, leading to the material being too brittle and the network being unbalanced.

[0013] Furthermore, the montmorillonite in the montmorillonite suspension is sodium-based montmorillonite.

[0014] Furthermore, the preparation method of the montmorillonite suspension includes the following steps: dispersing montmorillonite in water to obtain a suspension, stirring at room temperature to obtain a dispersion, centrifuging the dispersion, and obtaining the supernatant as the montmorillonite suspension.

[0015] Furthermore, the filter membrane has a specification of 0.22 µm.

[0016] Thirdly, the present invention provides an application of the above-mentioned sustainable smart plastic with shape memory and light management functions in smart agricultural greenhouse materials.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a sustainable smart plastic (S-plastic) with shape memory and light management functions, which is self-assembled from montmorillonite, gelatin, and tannic acid through vacuum filtration to form a composite film with an ordered layered structure. Its core innovation lies in utilizing a solvent (ethanol / water) to trigger reversible changes in the conformational transformation of the gelatin and supramolecular interactions within the material, thereby achieving three major functions: First, it can achieve ultra-rapid solvent fixation in ethanol and maintain the long-term stability of complex three-dimensional shapes; second, it can trigger shape recovery in water, exhibiting excellent shape memory effects; third, its optical properties can reversibly switch between high transparency and high haze under ethanol and water treatment. Furthermore, the material possesses the ability to convert ultraviolet light into visible light. The integration of these properties makes the sustainable smart plastic prepared by this invention particularly suitable for constructing intelligent actuators in agricultural greenhouses, promoting plant photosynthesis. Simultaneously, the material can rapidly biodegrade in the natural environment, demonstrating significant sustainability and application prospects. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Stress-strain curves of the gel films (3M / 7G film, 5M / 5G film, 7M / 3G film, 9M / 1G film) prepared in Example 1; Figure 2 Stress-strain curves of sustainable smart plastics (TA 0.04%, TA 0.08%, and TA 0.12%) with shape memory and light management functions prepared for Example 1; Figure 3 Reversible optical comparison images of S-plastic (TA 0.04%) prepared in Example 1; Figure 4 The experimental process and product morphology diagram of processing and shaping of S-plastic (TA 0.04%) prepared in Example 1; Figure 5 The fluorescence emission spectrum of Treated S-plastic under ultraviolet excitation and the absorption spectrum of natural chloroplasts; Figure 6 The graph shows the biodegradability of S-plastic (TA 0.04%), commercial PE, and PVC prepared in Example 1. Figure 7 Tensile test diagrams of S-plastic (TA 0.04%) prepared in Example 1 and S-plastic-NM prepared in Comparative Example 1; Figure 8 Tensile test results for S-plastic (TA 0.04%) and Treated S-plastic prepared in Example 1; Figure 9 SEM image of S-plastic (TA 0.04%) prepared in Example 1. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] This invention provides a sustainable smart plastic with shape memory and light management functions, which is prepared by self-assembly of montmorillonite, gelatin and tannic acid through vacuum filtration; the sustainable smart plastic has an ordered layered structure.

[0026] This invention also provides a method for preparing a sustainable smart plastic with shape memory and light management functions. This invention utilizes supramolecular assembly of montmorillonite, gelatin, and tannic acid, and through a simple vacuum filtration process, successfully prepares a smart polymer plastic with a smart light conversion actuator structure that converts ultraviolet light into visible light to promote plant photosynthesis. The preparation process is simple and the performance is excellent. Specifically, it includes the following steps: (1) Prepare tannic acid (TA) aqueous solution by direct dissolution method: Add tannic acid and deionized water to a beaker and stir continuously with a magnetic stirrer to ensure that the tannic acid is fully dissolved and finally obtain a clear TA solution; (2) Prepare gelatin aqueous solution by heating and dissolving method: Add gelatin (Gelatin, Gel) and deionized water into a beaker, stir continuously with a magnetic stirrer, and heat in a water bath to ensure that the gelatin is completely dissolved, and finally obtain a clear gel solution; (3) Preparation of sodium-based montmorillonite (Na-MMT) suspension by centrifugal purification method: First, sodium-based montmorillonite is dispersed in deionized water to prepare a suspension. The suspension is continuously stirred by a magnetic stirrer to ensure that it is fully hydrated and dispersed. Then, the resulting suspension is centrifuged to remove the precipitate that has not been fully separated. The supernatant is collected, which is the Na-MMT suspension. (4) Preparation of MMT / Gel solution: The Na-MMT suspension prepared in step (3) and the Gel solution prepared in step (2) are mixed in equal volumes under magnetic stirring and stirred continuously so that the gelatin is fully adsorbed on the MMT nanosheets through physical interaction, thereby forming a uniform composite solution, which is called MMT / Gel solution. (5) Vacuum filter the MMT / Gel solution prepared in step (4) using a filter membrane to form a gel film on the filter membrane; (6) Using the gel film prepared in step (5) as a precursor, the TA solution prepared in step (1) was poured in and vacuum filtered to successfully achieve self-assembly and obtain bioplastic (S-plastic), which was then peeled off after drying.

[0027] In some preferred embodiments of the present invention, in step (1), the mass fraction of the TA aqueous solution is 0.04%; the magnetic stirrer continuously stirs at room temperature for 30 min; In some preferred embodiments of the present invention, in step (2), the mass fraction of the gelatin aqueous solution is 0.5%; the water bath heating temperature is 60 °C, and the stirring time is 30 min; In some preferred embodiments of the present invention, in step (3), the sodium montmorillonite is dispersed in deionized water to prepare a suspension with a mass fraction of 1%; the stirring temperature is room temperature, the stirring time is 7 days, the centrifugation speed is 3500 rpm, and the time is 15 min.

[0028] In some preferred embodiments of the present invention, in step (4), the temperature of the continuous stirring is room temperature and the time is 12h; In some preferred embodiments of the present invention, the filter membrane has a specification of 0.22 µm.

[0029] This invention also provides an application of the above-mentioned sustainable smart plastic with shape memory and light management functions in smart agricultural greenhouse materials.

[0030] The room temperature in this invention refers to 25±2℃.

[0031] All raw materials used in this invention were purchased from the market.

[0032] In the embodiments of this invention, the ethanol solvent refers to anhydrous ethanol.

[0033] Example 1 S1. Preparation of tannic acid (TA) aqueous solution by direct dissolution method: Add different masses of tannic acid and deionized water to a 250 mL beaker, place it on a magnetic stirrer, and stir continuously for 30 min at room temperature to ensure that the tannic acid is fully dissolved, and prepare TA aqueous solutions of 0.04 wt.%, 0.08 wt% and 0.12 wt%; S2. Prepare a 0.5% gelatin aqueous solution by heating and dissolving: Add 0.5 g gelatin and 99.5 g deionized water to a 250 mL beaker, place it on a magnetic stirrer, and stir continuously for 30 min in a 60 ℃ water bath to ensure that the gelatin is completely dissolved, and finally obtain a clear gel solution. S3. Preparation of sodium-based montmorillonite suspension by centrifugal purification method: Sodium-based montmorillonite was dispersed in deionized water to prepare a suspension with a mass fraction of 1%. The suspension was stirred continuously at room temperature for 7 days to ensure full hydration and dispersion. The resulting dispersion was then centrifuged at 3500 rpm for 15 min to separate and remove the precipitate that was not fully stripped. The supernatant collected at the end was the required Na-MMT suspension. S4. At room temperature, the Na-MMT suspension prepared in step S3 and the Gel solution prepared in step S2 are mixed at volume ratios of 3:7, 5:5, 7:3 and 9:1, respectively, and mixed under magnetic stirring for 12 h, so that the gelatin is fully adsorbed on the MMT nanosheets through physical interaction, thereby forming 4 uniform composite solutions, denoted as MMT / Gel solutions. S5. The four MMT / Gel solutions prepared in step S4 are vacuum filtered through a 0.22 µm filter membrane to form gel films on the filter membrane, which are respectively denoted as 3M / 7G film, 5M / 5G film, 7M / 3G film and 9M / 1G film.

[0034] Figure 1 The stress-strain curves of the gel films (3M / 7G film, 5M / 5G film, 7M / 3G film, 9M / 1G film) prepared in Example 1 are shown below. Figure 1 It can be seen that the 5M / 5G film exhibits the strongest mechanical properties, reaching 14.5 MPa. Increasing the volume of the gelatin solution (3M / 7G film) leads to excessively high system viscosity, which in turn affects the uniform dispersion of the MMT sheets. Simultaneously, the relatively insufficient content of the reinforcing phase (MMT) per unit volume may weaken the interfacial bonding between gelatin and MMT, ultimately resulting in a softer film material and reduced strength. Therefore, this invention determines that the Na-MMT suspension prepared in step S3 and the gel solution prepared in step S2 should be mixed in an equal volume ratio during the preparation of the gel film.

[0035] S6. Prepare three 5M / 5G films according to step S5, and use them as precursors. Pour them into the TA solution prepared in S1 (concentrations of 0.04 wt.%, 0.08 wt%, and 0.12 wt%, respectively), and perform vacuum filtration. The volume ratio of Na-MMT suspension, gel solution, and TA solution is 1:1:2. Bioplastics are obtained through self-assembly. After drying, they are peeled off to obtain sustainable smart plastics (S-plastic) with shape memory and light management functions, which are denoted as TA0.04%, TA0.08%, and TA0.12%, respectively.

[0036] Figure 2 The stress-strain curves of the sustainable smart plastics (TA 0.04%, TA 0.08%, and TA 0.12%) with shape memory and light management functions prepared in Example 1 are shown below. Figure 2 As can be seen, when the TA solution concentration is 0.04%, the tensile strength of the prepared sustainable smart plastic reaches a maximum of 24 MPa. When the tannic acid concentration further increases to 0.08%, the strain properties of the material decrease; when the tannic acid concentration further increases to 0.12%, both the stress and strain properties of the material decrease. This may be because excessive tannic acid leads to excessively high crosslinking density, making the material brittle, and may also cause uneven distribution of the crosslinking network or generate agglomeration defects, thereby impairing mechanical properties. Therefore, this invention determines the concentration of the TA solution to be 0.04 wt.%.

[0037] Figure 9 SEM image of S-plastic (TA 0.04%) prepared in Example 1, from... Figure 9 As can be seen from the present invention, the sustainable smart plastic with shape memory and light management functions has an ordered layered structure.

[0038] Comparative Example 1 S1. Prepare a 0.5% gelatin aqueous solution by heating and dissolving: Add 0.5 g gelatin and 99.5 g deionized water to a 250 mL beaker, place it on a magnetic stirrer, and stir continuously for 30 min under a 60℃ water bath to ensure that the gelatin is completely dissolved, and finally obtain a clear gel solution. S2. Add 0.04g of tannic acid to the gel solution prepared in step S1, pour the resulting solution into a plastic mold (10cm×10cm), and evaporate at room temperature for 3 days to obtain S-plastic-NM material.

[0039] Performance testing 1. Reversible optical performance testing The S-plastic (TA 0.04%) prepared in Example 1 was soaked in ethanol solvent for 1 min to obtain Treated S-plastic, which was white. Then, the Treated S-plastic was soaked in water for 1 min to become transparent. After that, it was soaked in ethanol solvent for 1 min. This process was repeated multiple times, and the transparency was observed under visible light after each treatment.

[0040] Figure 3The images shown are reversible optical comparison test images of the S-plastic (TA 0.04%) prepared in Example 1. The S-plastic material prepared in this invention exhibits high optical transparency in its natural state. However, when treated with ethanol solvent, its transparency significantly decreases, and the material's appearance transforms into an opaque white state. If the ethanol-treated S-plastic material (Treated S-plastic) is transferred to a high-humidity environment or directly exposed to water, its optical state can be restored to high transparency. This "transparent-haze-transparent" transformation process can be repeated, demonstrating excellent reversibility and environmental responsiveness. The underlying mechanism of this optical behavior lies in the fact that the molecular conformation of the key component, gelatin, can undergo reversible changes depending on the polarity of the solvent. In an aqueous environment, gelatin molecules adopt a loose, random coil conformation with weak intermolecular forces, forming a relatively uniform and disordered macroscopic structure, resulting in high transmittance in the visible light range. However, in low-polarity organic solvents such as ethanol, gelatin molecules transform into a highly ordered β-sheet conformation, with tighter chain arrangement and directional aggregation. This leads to the formation of nano- to micro-scale phase-separated regions within the material. The significant differences in refractive index between these micro-regions induce strong scattering effects when light passes through, significantly increasing the material's haze and decreasing its transparency. This invention achieves reversible switching between the random coil and β-sheet conformations of gelatin molecules in S-plastic through alternating treatment with water and ethanol, thereby controlling the overall optical properties of the material. The process exhibits good repeatability, rapid response, and excellent material stability, enabling the creation of a smart material with reversible transparency and haze conversion, possessing promising application prospects and industrialization potential.

[0041] 2. Processing and shaping test The S-plastic (TA 0.04%) prepared in Example 1 was made into elongated strips (four parallel preparations) and treated at 90% relative humidity (25°C, 90%RH for 10 min in a constant temperature and humidity chamber) to obtain moist S-plastic. Using a cylindrical template, the elongated and moist S-plastic were respectively made into spiral, pentagonal, and ring shapes, and then quickly immersed in ethanol solvent for about 30 seconds for fixation. After removal, they were dried in air for 1-2 minutes and then placed at room temperature for 30 days. Figure 4 The experimental process and product morphology diagram for processing and shaping of S-plastic (TA 0.04%) prepared in Example 1 are shown below. Figure 4As can be seen, the S-plastic material prepared in this invention can stably maintain its temporary shape after treatment with ethanol. The fundamental reason for this unique property lies in the fact that ethanol can induce a significant conformational change in the gelatin molecular chains and greatly enhance the interaction between gelatin molecules. Specifically, when S-plastic is immersed in ethanol, the molecular conformation of gelatin changes from a loose, random coil state to an ordered β-sheet. This change makes the molecular chain arrangement more compact and orderly. More importantly, in the ethanol environment, the interaction energy between gelatin molecules is significantly enhanced, far exceeding its interaction energy in water, and also far greater than the interaction force between gelatin and tannic acid at this time. This dominant and strong intermolecular interaction forms a stable, new cross-linked network, thereby firmly locking the temporary shape of the material after deformation. S-plastic can be rapidly shaped and fixed in ethanol conditions. This process is mainly attributed to the structural changes of gelatin in ethanol, the enhancement of intermolecular interactions, and the rapid volatility of ethanol itself. Specifically, gelatin transforms from a randomly coiled structure to a more ordered β-sheet structure in ethanol. This structural change significantly enhances the hydrogen bonds and van der Waals forces between gelatin molecules, enabling the plastic to quickly solidify its shape. Simultaneously, ethanol, as an organic solvent, exhibits rapid evaporation, further promoting the rapid curing process of the plastic. Furthermore, the synergistic effects between other components of S-plastic, such as montmorillonite and tannic acid, and gelatin also change significantly in ethanol, further enhancing the mechanical properties of the plastic. These factors work together to enable S-plastic to be rapidly molded in ethanol and maintain a stable shape over a long period.

[0042] 3. Ultraviolet-Visible Light Absorption Performance Test The S-plastic (TA 0.04%) prepared in Example 1 was immersed in ethanol solvent for 1 min to obtain Treated S-plastic.

[0043] Purchase fresh spinach for extracting intact chloroplasts. All operations should be performed in the dark at 0-4℃ to avoid chloroplast degradation and light damage. The specific steps include: Take approximately 10 g (about 6-7 leaves) of spinach leaves, wash them, and cut them into small pieces of approximately 1.5 cm × 1.5 cm. Prepare a sucrose buffer solution with a pH of 7.3 by weighing 0.4 M sucrose, 0.02 M KH₂PO₄, 0.03 M Na₂HPO₄, and 0.01 M KCl, and adding deionized water to a final volume of 10 mL. The chopped spinach leaves were placed in a mortar containing the above-mentioned sucrose buffer and ground thoroughly to release chloroplasts from the cells. The ground mixture was filtered through four layers of cotton gauze to remove larger cell debris and impurities. The filtrate was centrifuged at 1000 rpm for 3 min and the supernatant was collected. The supernatant was then centrifuged at 3000 rpm for 3 min and the precipitate was collected to obtain chloroplasts. Finally, the chloroplast precipitate was resuspended in the same sucrose buffer to prepare a chloroplast suspension (10 μg / mL).

[0044] The absorption spectra of the above-mentioned treated S-plastic in the 200-800 nm range were tested with a step size of 0.5 nm. The absorption spectra of the above-mentioned chloroplast suspension in the 200-800 nm range were also tested with a step size of 0.5 nm. The results are as follows: Figure 5 As shown, the key to the preparation method of S-plastic material provided by this invention lies in constructing a supramolecular composite system using montmorillonite (MMT), gelatin, and tannic acid. This structure can serve as a highly efficient light conversion platform. Its mechanism of action is as follows: S-plastic material can absorb ultraviolet light that is harmful to plants and cannot be utilized, and through intermolecular energy transfer processes, convert it into visible light that chloroplasts can effectively absorb. The emission spectrum of treated treated S-plastic under ultraviolet light excitation is highly consistent with the absorption spectrum of natural chloroplasts, which directly confirms the "ultraviolet to visible light" conversion mechanism, that is, the material can "upgrade" harmful ultraviolet radiation into effective energy that can be used for photosynthesis.

[0045] 4. Degradability test The S-plastic (TA 0.04%) prepared in Example 1 was cut into squares (1cm × 1cm). The resulting square S-plastics, along with polyethylene (PE) and polyvinyl chloride (PVC) of the same size, were buried in the soil, and the degradation was recorded after 5 days, 16 days, and 22 days, respectively.

[0046] Figure 6 This is a graph recording the biodegradability of S-plastic, commercial PE, and PVC prepared in Example 1. Figure 6The S-plastic prepared by this invention exhibits excellent biodegradability in soil burial experiments, showing significant degradation in just 22 days, a stark contrast to traditional non-degradable polyethylene (PE) and polyvinyl chloride (PVC). Its degradation mechanism is primarily attributed to its natural components and unique structure: the core components of S-plastic, gelatin (protein) and tannic acid (polyphenol), are easily recognizable natural substrates for microorganisms and can be hydrolyzed by microbial enzymes; simultaneously, the multilayered structure of the material facilitates the penetration of water and microorganisms, thereby accelerating the disintegration of the entire material structure from the inside out, ultimately achieving rapid and thorough environmental return.

[0047] 5. Mechanical property testing Strength tests were performed on the S-plastic (TA 0.04%) prepared in Example 1, the S-plastic-NM prepared in Comparative Example 1, and the Treated S-plastic. Figure 7 Tensile test results for S-plastic (TA 0.04%) prepared in Example 1 and S-plastic-NM prepared in Comparative Example 1 are shown below. Figure 7 As shown, the tensile strength of the S-plastic prepared in this invention is 24 MPa. As a control, the tensile strength of S-plastic-NM without MMT is 12 MPa. The tensile strength of S-plastic is twice that of the control group S-plastic-NM without montmorillonite (MMT), mainly because MMT plays a crucial reinforcing role as a nanofiller. The MMT nanosheets are uniformly dispersed in a matrix composed of gelatin and tannic acid, forming a nanocomposite structure. This not only enhances the overall integrity of the material through interfacial interactions (such as hydrogen bonds), but its rigid sheets also effectively restrict the movement of gelatin molecular chains, transmit and disperse stress, thereby significantly improving the mechanical strength and modulus of the material.

[0048] Figure 8 Tensile test results for S-plastic (TA 0.04%) and Treated S-plastic prepared in Example 1 are shown below. Figure 8 As shown, the tensile strength of S-plastic is significantly improved after ethanol treatment. The fundamental reason for this is that ethanol induces a conformational change in gelatin molecules from random coil to β-sheet, forming a more ordered and dense secondary structure. This conformational change enhances the interaction forces between gelatin molecules and makes the lamellar structure inside the material more compact and more oriented, thus jointly leading to the enhancement of the material's mechanical properties.

[0049] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A sustainable smart plastic with shape memory and light management functions, characterized in that, It was prepared by self-assembly of montmorillonite, gelatin and tannic acid through vacuum filtration.

2. The sustainable smart plastic with shape memory and light management functions according to claim 1, characterized in that, The sustainable smart plastic has an ordered layered structure.

3. A method for preparing a sustainable smart plastic with shape memory and light management functions as described in claim 1 or 2, characterized in that, Includes the following steps: A composite solution was prepared by mixing a montmorillonite suspension with a gelatin aqueous solution. The composite solution was then vacuum filtered to form a gel film on the filter membrane. A tannic acid aqueous solution was then poured in and vacuum filtered again. After drying, the mixture was peeled off to prepare the sustainable smart plastic with shape memory and light management functions.

4. The method for preparing sustainable smart plastics with shape memory and light management functions according to claim 3, characterized in that, The concentration of the montmorillonite suspension is 1 wt.%; the concentration of the gelatin aqueous solution is 0.5%; the mass concentration of the tannic acid aqueous solution is 0.04%; and the volume ratio of the montmorillonite suspension, gelatin aqueous solution, and tannic acid aqueous solution is 1:1:

2.

5. The method for preparing sustainable smart plastics with shape memory and light management functions according to claim 3, characterized in that, The montmorillonite in the montmorillonite suspension is sodium-based montmorillonite.

6. The method for preparing sustainable smart plastics with shape memory and light management functions according to claim 3, characterized in that, The preparation method of the montmorillonite suspension includes the following steps: dispersing montmorillonite in water to obtain a suspension, stirring at room temperature to obtain a dispersion, centrifuging the dispersion, and obtaining the supernatant as the montmorillonite suspension.

7. The method for preparing sustainable smart plastic with shape memory and light management functions according to claim 3, wherein the filter membrane has a specification of 0.22 µm.

8. The application of a sustainable smart plastic with shape memory and light management functions as described in claim 1 or 2 in smart agricultural greenhouse materials.

Images