Innovative preparation method of environment-friendly degradable acrylic plate

Abstract

The invention relates to the technical field of high polymer materials, and discloses an innovative preparation method of an environment-friendly degradable acrylic sheet material, the sheet material is prepared from methyl methacrylate, 2-hydroxyethyl methacrylate, autocatalytic precursor functionalized furfural derivative lactone, an enzyme response type diene cross-linking agent, 1, 4-benzene diboronic acid and other raw materials. The preparation method comprises three steps of prepolymer syrup preparation, pouring and dynamic network construction, and final curing and annealing treatment, and an acetal structure sensitive to acid and a peptide bond structure sensitive to biological enzyme are introduced into a polymer network, so that the material has dual controllable degradation characteristics of autocatalytic chemical degradation and biological enzyme degradation at the same time; and by constructing a dynamic reversible boric acid ester cross-linked network, the material is endowed with excellent thermal remodeling and damage self-repairing capabilities. The board prepared by the invention solves the problem that the traditional acrylic material is difficult to degrade and cannot be repaired and reused after being discarded on the basis of retaining good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to an innovative preparation method for environmentally friendly biodegradable acrylic sheets. Background Technology

[0002] Polymethyl methacrylate (PMMA) sheets, commonly known as acrylic sheets or plexiglass, are widely used in many fields such as architectural decoration, advertising light boxes, transportation vehicles, and optical instruments due to their excellent optical transparency, good weather resistance, stable chemical properties, and outstanding machinability.

[0003] However, while traditional acrylic sheets are widely used, they also have inherent technical drawbacks. Firstly, their polymer backbone is composed of stable carbon-carbon single bonds. For high-performance sheets, they typically also contain a permanent cross-linked network of covalent bonds. This chemical structure endows the material with high stability, but also makes it extremely difficult to degrade in the natural environment. Discarded acrylic products persist in the environment for a long time, occupying significant amounts of land resources and potentially forming microplastics, posing a continuous and potential threat to the ecological environment.

[0004] Secondly, the aforementioned permanent cross-linked network structure means that once the material has solidified, its internal topology is fixed. When the sheet material suffers mechanical damage such as scratches, impacts, or cracks during use, it cannot be repaired by simple physical or chemical methods, shortening the product's lifespan. Simultaneously, this thermosetting network structure also prevents the material from being recycled and reused like thermoplastics through heating and melting. Its recycling typically relies on complex chemical depolymerization processes, which are costly and inefficient, resulting in significant resource waste. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an innovative preparation method for environmentally friendly biodegradable acrylic sheets. Traditional acrylic sheets are difficult to degrade after disposal and cannot be repaired and reused after damage during use, resulting in environmental pollution and resource waste.

[0006] To achieve the above objectives, the present invention provides a method for preparing an environmentally friendly biodegradable acrylic sheet.

[0007] The first aspect of this invention provides a method for preparing an environmentally friendly biodegradable acrylic sheet, the method comprising the following steps: (a) Preparation of prepolymer syrup: The raw material components are mixed evenly and prepolymerized under light to obtain a prepolymer syrup with a viscosity of 800-1200 mPa·s; the raw material components, by weight, include: 70-80 parts of methyl methacrylate; 15-25 parts of autocatalytic precursor functionalized furfural-derived lactone; 1-3 parts of 2-hydroxyethyl methacrylate; 1-3 parts of enzyme-responsive diene crosslinking agent; and 0.2-0.5 parts of photoinitiator.

[0008] (b) Casting and dynamic network construction: 1,4-phenylenediboric acid is added to the prepolymer syrup, mixed evenly, and then cast into a mold and heated at 80-95°C for 2.5-3.5 hours to form a dynamic and reversible borate ester crosslinking network.

[0009] (c) Final curing and annealing: The product obtained in step (b) is cured by light, then demolded and annealed to obtain the environmentally friendly biodegradable acrylic sheet.

[0010] In this technical solution, by introducing two functional monomers with specific structures and constructing a dynamic cross-linking network, the biodegradability and remodelability of acrylic sheets are achieved. The technical mechanism is as follows: The introduction of a dual degradation mechanism: The molecular structure of the autocatalytic precursor functionalized furfural-derived lactone contains an acid-sensitive acetal structure. In acidic aqueous solutions, this structure can break down and release acidic small molecules, thereby accelerating the chain-breaking degradation of the material itself. Simultaneously, the molecular structure of the enzyme-responsive diene crosslinking agent contains peptide bonds, which can break down under the action of specific biological enzymes, thereby disrupting the crosslinking network structure of the polymer and achieving enzyme-controlled degradation. The combination of these two structures endows the final board with the dual characteristics of autocatalytic degradation and enzyme-responsive degradation.

[0011] Construction of a dynamic covalent network: The 2-hydroxyethyl methacrylate in the raw material component contains a vicinal diol structure, which can undergo a dehydration reaction with 1,4-phenylenediboric acid to form a dynamically reversible borate ester bond. This chemical bond undergoes reversible breakage and recombination under thermal stimulation, thereby constructing a dynamically reversible cross-linked network. The existence of this network allows the cured acrylic sheet to be reshaped and repaired under heating conditions.

[0012] To achieve the above technical solution, in some specific implementation methods: The preparation method of the autocatalytic precursor functionalized furfural-derived lactone includes the following steps: 5-hydroxymethylfurfural is reacted with acetic anhydride at a molar ratio of 1:(1.2-1.5) to acetylate and protect the hydroxyl group, yielding 5-(acetoxymethyl)furfural; then, the 5-(acetoxymethyl)furfural is reacted with sodium borohydride at a molar ratio of 1:(1.0-1.2) to reduce the aldehyde group to a hydroxyl group, yielding [5-(acetoxymethyl)furan-2-yl]methanol; then, at 0-5℃, using rose red as a photosensitizer and a light source with a wavelength of 520-550 nm, the [5-(acetoxymethyl)furan-2-yl]methanol is subjected to photo-oxygen reaction to construct a lactone ring, yielding the lactone product; finally, the lactone product, methacryloyl chloride, and triethylamine are reacted at a molar ratio of 1:(1.2-1.5):(1.5-2.0) to introduce a polymeric double bond, thus preparing the autocatalytic precursor functionalized furfural-derived lactone.

[0013] The preparation method of the enzyme-responsive diene crosslinking agent includes: Using 1,4-diaminobutane, N-methacryloyl-L-alanine, EDC·HCl and HOBt as raw materials, an amidation reaction was carried out at a molar ratio of 1:(2.2-2.5):(2.5-3.0):(2.5-3.0) to obtain the enzyme-responsive diene crosslinking agent.

[0014] In step (a), the raw material components further include 0.1-0.5 parts of a chain transfer agent, wherein the chain transfer agent is dodecyl mercaptan.

[0015] The photoinitiator is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0016] To ensure precise control of the preparation process, the photopolymerization in step (a) is carried out using an LED light source with a wavelength of 395-405nm at a temperature of 30-40℃.

[0017] To construct an effective dynamic network, in step (b), the molar ratio of 1,4-phenylenediboric acid to 2-hydroxyethyl methacrylate is 0.9:2 to 1.05:2.

[0018] To ensure product uniformity and remove air bubbles in the system, step (b) includes, after adding the 1,4-phenylenediboric acid and before pouring it into the mold, a step of stirring and degassing the prepolymer syrup containing 1,4-phenylenediboric acid under a vacuum of -0.08 to -0.09 MPa.

[0019] To obtain a fully cured board, the photocuring in step (c) uses an LED light source with a wavelength of 395-405nm, and alternately irradiates both sides for 30-45 minutes.

[0020] To eliminate internal stress in the material and stabilize its properties, the annealing process in step (c) is as follows: the temperature is raised from room temperature to 105-115°C at a rate of 3-5°C / min, held at the constant temperature for 1.5-2.5 hours, and then slowly cooled to below 40°C at a rate of 1-2°C / min.

[0021] This invention provides an innovative method for preparing environmentally friendly biodegradable acrylic sheets. It offers the following advantages: This technical solution introduces an acid-sensitive acetal structure and an enzyme-sensitive peptide bond structure by copolymerizing two functional monomers in the polymer structure. The former can self-catalytically break down in an acidic aqueous solution environment, accelerating the chemical degradation of the material; the latter can undergo chain segment breakage under the action of specific biological enzymes. The coexistence of two degradation pathways with different mechanisms makes the degradation behavior of the final board environmentally responsive and designable, improving the controllability of the degradation process. This technical solution constructs a dynamic and reversible borate ester crosslinking network in a permanent acrylate network through the reaction between 2-hydroxyethyl methacrylate and 1,4-phenylenediboronic acid. The borate ester bonds in this dynamic network can undergo reversible breakage and recombination under thermal stimulation, giving the cured board the ability to reconstruct its network, thereby enabling repeated heating and processing of the board, shape reshaping, and repair of physical damage. This technical solution controls the system to a specific viscosity of 800-1200 mPa·s through photopolymerization, ensuring the uniformity of subsequent casting; the vacuum degassing step effectively removes air bubbles in the system, avoiding product defects; and the precisely controlled annealing process eliminates the internal stress of the material, ensuring the stability and repeatability of the final product's performance, which is beneficial for industrial production. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Methyl methacrylate, CAS No.: 80-62-6; 2-Hydroxyethyl methacrylate, CAS No.: 868-77-9; Phenylacetylbis(2,4,6-trimethylbenzoyl)phosphine oxide, CAS No.: 162881-26-7; 1,4-Phenylatedorboic acid, CAS No.: 4612-26-4; Dodecyl mercaptan, CAS No.: 112-55-0; 5-Hydroxymethylfurfural, CAS No.: 67-47-0; Acetic anhydride, CAS No.: 108-24-7; Sodium borohydride, CAS No.: 16940-66-2; Rose red, CAS No.: 632-69-9; Methacryloxychloride, CAS No.: 920-46-7; Triethylamine, CAS No.: 121-44-8; 1,4-Diaminobutane, CAS No.: 110-60-1; N-Methacryl-L-alanine, CAS No.: 54673-07-3; 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, CAS No.: 25952-53-8; Hydroxybenzotriazole, CAS No.: 2592-95-2; Ethylene glycol dimethacrylate, CAS No.: 97-90-5.

[0024] Preparation Examples 1-2: Preparation Example 1: Preparation of autocatalytic precursor functionalized furfural-derived lactone (1) Synthesis of 5-(acetoxymethyl)furfural: 12.61 g (0.1 mol) of 5-hydroxymethylfurfural and 250 mL of anhydrous dichloromethane were added sequentially to a 500 mL round-bottom flask equipped with a magnetic stirrer. Acetic anhydride 13.27 g (0.13 mol) was slowly added dropwise under ice bath cooling. After the addition was complete, the ice bath was removed, and the reaction was allowed to proceed at room temperature for 12 hours. After the reaction was complete, 100 mL of saturated sodium bicarbonate solution was added to the reaction solution to quench the reaction. The mixture was separated, and the aqueous phase was extracted with dichloromethane (50 mL × 3). The combined organic phases were washed sequentially with water and saturated brine, and dried over anhydrous magnesium sulfate. After filtration, the solvent was removed by rotary evaporation under reduced pressure to obtain 16.5 g of a yellow oily liquid, 5-(acetoxymethyl)furfural, with a yield of 98%.

[0025] (2) Synthesis of [5-(acetoxymethyl)furan-2-yl]methanol: 16.82 g (0.1 mol) of 5-(acetoxymethyl)furfural prepared in step (1) and 200 mL of methanol were added to a 500 mL round-bottom flask and stirred to dissolve. 4.16 g (0.11 mol) of sodium borohydride was added in batches under ice bath cooling. After the addition was complete, the reaction was continued at 0 °C for 2 hours. After the reaction was complete, the pH was adjusted to 6-7 with 2 M hydrochloric acid solution, and most of the methanol was removed by rotary evaporation under reduced pressure. 200 mL of water was added to the residue, and the mixture was extracted with ethyl acetate (80 mL × 3). The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain 16.7 g of [5-(acetoxymethyl)furan-2-yl]methanol, a pale yellow oily liquid, with a yield of 98%.

[0026] (3) Synthesis of the lactone product: 17.02 g (0.1 mol) of [5-(acetoxymethyl)furan-2-yl]methanol obtained in step (2) and 0.1 g of rose red were dissolved in 300 mL of methanol and placed in a photochemical reactor. Oxygen was continuously introduced at 0-5 °C, and the reaction was irradiated with an LED light source with a center wavelength of 535 nm for 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 3:1) to obtain 18.1 g of the target lactone product as a white solid, with a yield of 89%.

[0027] (4) Synthesis of autocatalytic precursor functionalized furfural-derived lactone: 20.22 g (0.1 mol) of the lactone product obtained in step (3), 13.15 g (0.13 mol) of triethylamine, and 150 mL of anhydrous dichloromethane were added to a 250 mL three-necked flask and stirred under nitrogen protection and ice bath cooling. A 50 mL solution of anhydrous dichloromethane containing 12.54 g (0.12 mol) of methacryloyl chloride was slowly added dropwise. After the addition was complete, the reaction was continued at 0 °C for 2 hours, and then raised to room temperature for 12 hours. After the reaction was completed, the triethylamine hydrochloride precipitate was removed by filtration. The filtrate was washed successively with 1 M hydrochloric acid, saturated sodium bicarbonate solution, and saturated brine. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain 24.5 g of the target product, autocatalytic precursor functionalized furfural-derived lactone, which was a colorless viscous liquid with a yield of 91%.

[0028] Preparation Example 2: Preparation of Enzyme-Responsive Diene Crosslinking Agent To a 500 mL three-necked flask, add 32.9 g (0.23 mol) of N-methacryloyl-L-alanine, 35.1 g (0.26 mol) of hydroxybenzotriazole (HOBt), and 300 mL of anhydrous N,N-dimethylformamide (DMF), and stir until completely dissolved. Cool the reaction system to 0 °C in an ice-water bath, add 49.8 g (0.26 mol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl), and activate at 0 °C with stirring for 30 minutes. Then, slowly add 50 mL of anhydrous DMF solution containing 8.82 g (0.1 mol) of 1,4-diaminobutane. After the addition is complete, remove the ice bath, raise the reaction system to room temperature, and stir for 48 hours. After the reaction is complete, pour the reaction solution into 2 L of deionized water, where a white precipitate forms. The precipitate was collected by vacuum filtration and washed several times with a large amount of deionized water to remove water-soluble impurities. The obtained solid was dried in a vacuum oven at 60°C for 24 hours to obtain 30.5 g of a white powder product, an enzyme-responsive diene crosslinking agent, with a yield of 87%.

[0029] Examples 1-3: Example

[0030] This embodiment provides a method for preparing an environmentally friendly biodegradable acrylic sheet, the specific steps of which are as follows: (1) Preparation of prepolymer syrup According to the specified weight parts, 75 parts of methyl methacrylate, 20 parts of the autocatalytic precursor functionalized furfural-derived lactone prepared in Preparation Example 1, 2 parts of 2-hydroxyethyl methacrylate, 2 parts of the enzyme-responsive diene crosslinking agent prepared in Preparation Example 2, 0.35 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 0.3 parts of dodecyl mercaptan were added to a reaction vessel and mechanically stirred until they were mixed evenly. Subsequently, the mixture was irradiated with an LED light source with a wavelength of 400 nm at a temperature of 35°C to carry out a prepolymerization reaction until the viscosity of the system reached 1000 mPa·s, at which point the irradiation was stopped, and a prepolymer syrup was obtained.

[0031] (2) Casting and Dynamic Network Construction Add 0.23 parts of 1,4-phenylenediboric acid (to make the molar ratio of 1,4-phenylenediboric acid to 2-hydroxyethyl methacrylate 1:2) to the prepolymer syrup obtained in step (1), and stir until homogeneous. Transfer the mixture to a vacuum drying oven and stir to degas for 15 minutes under a vacuum of -0.085 MPa. Pour the degassed syrup into a mold consisting of two glass plates and a sealing strip. Place the mold in an oven and heat at 88°C for 3 hours.

[0032] (3) Final curing and annealing treatment Remove the mold and allow it to cool to room temperature. Irradiate the mold alternately on both sides using a 400nm LED light source for 20 minutes on each side, for a total of 40 minutes, to ensure complete curing. Remove the cured board from the mold and then perform annealing. The annealing procedure is as follows: heat from room temperature to 110℃ at a rate of 4℃ / min, hold at that temperature for 2 hours, and then slowly cool to below 40℃ at a rate of 1.5℃ / min to obtain the acrylic board of Example 1. Example

[0033] This embodiment provides a method for preparing an environmentally friendly biodegradable acrylic sheet, the specific steps of which are as follows: (1) Preparation of prepolymer syrup According to the specified weight parts, 70 parts of methyl methacrylate, 15 parts of the autocatalytic precursor functionalized furfural-derived lactone obtained in Preparation Example 1, 1 part of 2-hydroxyethyl methacrylate, 1 part of the enzyme-responsive diene crosslinking agent obtained in Preparation Example 2, 0.2 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 0.1 parts of dodecyl mercaptan were added to a reaction vessel and mixed thoroughly. Prepolymerization was carried out at 30°C using an LED light source with a wavelength of 395 nm until the system viscosity reached 800 mPa·s, yielding a prepolymer syrup.

[0034] (2) Casting and Dynamic Network Construction Add 0.11 parts of 1,4-phenylenediboric acid (to make the molar ratio of 1,4-phenylenediboric acid to 2-hydroxyethyl methacrylate 0.9:2) to the prepolymer syrup obtained in step (1), and stir until homogeneous. Stir and degas at a vacuum of -0.08 MPa for 20 minutes. Pour the degassed syrup into a mold and heat at 80°C for 3.5 hours.

[0035] (3) Final curing and annealing treatment Remove the mold and allow it to cool to room temperature. Irradiate both sides alternately with a 395nm LED light source for 15 minutes on each side, for a total of 30 minutes. After demolding, perform annealing. The annealing procedure is as follows: heat from room temperature to 105℃ at a rate of 3℃ / min, hold at that temperature for 2.5 hours, and then slowly cool to below 40℃ at a rate of 2℃ / min to obtain the acrylic sheet of Example 2. Example

[0036] This embodiment provides a method for preparing an environmentally friendly biodegradable acrylic sheet, the specific steps of which are as follows: (1) Preparation of prepolymer syrup According to the specified weight parts, 70 parts of methyl methacrylate, 25 parts of the autocatalytic precursor functionalized furfural-derived lactone obtained in Preparation Example 1, 3 parts of 2-hydroxyethyl methacrylate, 3 parts of the enzyme-responsive diene crosslinking agent obtained in Preparation Example 2, 0.5 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 0.5 parts of dodecyl mercaptan were added to a reaction vessel and mixed thoroughly. Prepolymerization was carried out at 40°C using an LED light source with a wavelength of 405 nm until the system viscosity reached 1200 mPa·s, yielding a prepolymer syrup.

[0037] (2) Casting and Dynamic Network Construction Add 0.38 parts of 1,4-phenylenediboric acid (to make the molar ratio of 1,4-phenylenediboric acid to 2-hydroxyethyl methacrylate 1.05:2) to the prepolymer syrup obtained in step (1), and stir until homogeneous. Stir and degas at a vacuum of -0.09 MPa for 10 minutes. Pour the degassed syrup into a mold and heat at 95°C for 2.5 hours.

[0038] (3) Final curing and annealing treatment Remove the mold and allow it to cool to room temperature. Irradiate both sides alternately with a 405nm LED light source for 22.5 minutes on each side, for a total of 45 minutes. After demolding, perform annealing. The annealing procedure is as follows: heat from room temperature to 115℃ at a rate of 5℃ / min, hold at that temperature for 1.5 hours, and then slowly cool to below 40℃ at a rate of 1℃ / min to obtain the acrylic sheet of Example 3.

[0039] Comparative Examples 1-2: Comparative Example 1: Compared with Example 1, the difference is that in step (1), the self-catalytic precursor functionalized furfural-derived lactone and the enzyme-responsive diene crosslinking agent are not added, but are replaced with 20 parts of methyl methacrylate and 2 parts of ethylene glycol dimethacrylate, respectively. The remaining preparation steps and conditions are the same as in Example 1.

[0040] Comparative Example 2: The difference from Example 1 is that 1,4-phenylenediboric acid is not added in step (2). The remaining preparation steps and conditions are the same as in Example 1.

[0041] Test Examples 1-4: Test Example 1: Mechanical Property Test Experimental steps: According to GB / T1040.2-2006 standard, the prepared sheet metal samples were cut and processed into dumbbell-shaped Type II strips for tensile property testing. According to GB / T9341-2008 standard, the sheet metal samples were cut into cuboid strips for bending property testing. All strips were placed in an environment with a temperature of 23℃ and a relative humidity of 50% for more than 24 hours before testing.

[0042] The tests were conducted using a universal testing machine. For tensile testing, the tensile rate was set to 5 mm / min, and the tensile strength and elongation at break of the samples were recorded. For bending testing, a three-point bending mode was used, with a loading rate set to 2 mm / min, and the flexural modulus of the samples was recorded. Five spline samples were tested for each group of samples, and the results were taken as the arithmetic mean.

[0043] Experimental data: Table 1. Mechanical property test results of each embodiment and comparative example. Sample number Tensile strength (MPa) Elongation at break (%) Flexural modulus (GPa) Example 1 67.3 6.1 2.90 Example 2 65.8 5.9 2.85 Example 3 68.1 6.5 2.94 Comparative Example 1 70.2 5.2 3.01 Comparative Example 2 69.5 4.8 3.05 The test data in Table 1 show that the sheets prepared in Examples 1-3 have the same tensile strength, elongation at break, and flexural modulus as the conventional acrylic sheet in Comparative Example 1. This result demonstrates that the introduction of specific functional monomers in the technical solution of this invention did not lead to a deterioration of the basic mechanical properties of the material.

[0044] The mechanism behind this phenomenon lies in the fact that the overall mechanical framework of the material is primarily determined by the main chain formed by the polymerization of methyl methacrylate and the permanent covalent network formed by the cross-linking of methacryloyl double bonds. The introduction of the self-catalytically functionalized furfural-derived lactone and the enzyme-responsive diene cross-linking agent, whose weight proportions in the total composition fall within a specific range, ensures that while they participate in copolymerization to form the final network structure, they do not structurally damage the basic framework composed of methyl methacrylate, thus maintaining the macroscopic mechanical strength of the material.

[0045] Meanwhile, data from Comparative Example 2 show that its mechanical properties are close to those of Comparative Example 1, indicating that the construction of the dynamically reversible borate ester crosslinking network did not negatively affect the static mechanical properties of the material at room temperature. Therefore, this technical solution integrates degradable sites and dynamic chemical bonds in the polymer network of the material through the selection and proportioning of specific components, while fully preserving the mechanical support properties necessary for its application as a sheet material.

[0046] Test Example 2: Autocatalytic Degradation Performance Test Experimental steps: The plate samples obtained in Examples 1-3 and Comparative Examples 1-2 were cut into blocks with dimensions of 10mm × 10mm × 2mm. The blocks were dried in a vacuum oven at 60℃ to constant weight, and their initial mass was measured using an analytical balance with an accuracy of 0.1mg, denoted as . .

[0047] The weighed samples were placed in sealed sample vials containing 20 mL of acetate buffer solution at pH 5.0. All sample vials were then placed in a constant temperature water bath at 50°C for accelerated degradation experiments.

[0048] Samples were collected on days 7, 14, and 28, respectively. Their surfaces were repeatedly rinsed with deionized water, and then dried in a vacuum oven at 60°C until constant weight. The remaining mass was then measured and recorded as follows: According to the formula: Quality loss rate (%) = Calculate the mass loss rate of the samples. Three samples were tested in each group, and the results were taken as the arithmetic mean.

[0049] Experimental data: Table 2. Autocatalytic degradation test results of each example and comparative example. Sample number 7-day quality loss rate (%) 14-day quality loss rate (%) 28-day quality loss rate (%) Example 1 3.1 7.8 15.2 Example 2 2.5 6.1 12.9 Example 3 4.2 9.3 18.6 Comparative Example 1 0.2 0.3 0.4 Comparative Example 2 3.3 7.5 14.8 The test data in Table 2 show that, in an acidic buffer solution with pH 5.0, the samples of Examples 1-3 and Comparative Example 2 all exhibited a continuously increasing mass loss over time. In contrast, the sample of Comparative Example 1 maintained a relatively stable mass throughout the entire test period, and its mass loss rate was within the error range.

[0050] This result stems from the structural differences in the material components. The polymer networks of Examples 1-3 and Comparative Example 2 all contain autocatalytic precursor functionalized furfural-derived lactone units introduced through copolymerization. The molecular structure of this unit includes an acid-sensitive acetal structure. In an acidic aqueous solution at pH 5.0, this acetal structure undergoes hydrolytic cleavage, releasing acidic molecular fragments. These released acidic substances locally increase the acid concentration around the polymer chain, thereby catalyzing the hydrolysis of the ester groups in the polymer backbone, leading to polymer chain breakage and mass loss.

[0051] The sample in Comparative Example 1, because its raw material components do not contain the aforementioned autocatalytic precursor functionalized furfural-derived lactone, has a polymer network composed of conventional methyl methacrylate and ethylene glycol dimethacrylate, which are insensitive to acid hydrolysis. Therefore, it did not degrade under the same test conditions. This comparative result confirms that the present technical solution, by introducing specific acid-sensitive units into the polymer structure, endows the material with the function of autocatalytic degradation under specific acidic environments.

[0052] Test Example 3: Enzyme-responsive Degradation Performance Test Experimental steps: The plate samples obtained in Examples 1-3 and Comparative Examples 1-2 were cut into blocks with dimensions of 10mm × 10mm × 2mm. The blocks were dried in a vacuum oven at 60℃ to constant weight, and their initial mass was measured using an analytical balance with an accuracy of 0.1mg, denoted as . .

[0053] Prepare a phosphate-buffered saline (PBS, pH 7.4) solution for proteinase K to a final concentration of 0.5 mg / mL. Place the weighed sample blocks into sealed sample vials containing 20 mL of the proteinase K solution. Place all sample vials in a 37°C shaker for degradation experiments.

[0054] Samples were collected on days 7, 14, and 28, and their surfaces were repeatedly rinsed with copious amounts of deionized water to remove residual enzymes and salts. They were then dried in a vacuum oven at 60°C until constant weight, and the remaining mass was recorded as follows: According to the formula: Quality loss rate (%) = Calculate the mass loss rate of the samples. Three samples were tested in each group, and the results were taken as the arithmetic mean.

[0055] Experimental data: Table 3. Enzyme response degradation test results of each example and comparative example. Sample number 7-day quality loss rate (%) 14-day quality loss rate (%) 28-day quality loss rate (%) Example 1 4.5 10.1 19.8 Example 2 3.9 8.5 17.1 Example 3 5.3 11.6 22.4 Comparative Example 1 0.1 0.2 0.3 Comparative Example 2 4.2 9.8 19.1 The test data in Table 3 show that in the buffer solution containing proteinase K, the samples of Examples 1-3 and Comparative Example 2 all experienced significant mass loss, and the degree of loss increased over time. In contrast, the sample of Comparative Example 1 showed an extremely low mass loss rate over the 28-day test period, with the value within the measurement error range.

[0056] This test result is directly related to the cross-linked network structure of the material. Examples 1-3 and Comparative Example 2 all used an enzyme-responsive diene cross-linking agent. The molecular structure of this cross-linking agent contains peptide bonds (amide bonds) formed by the reaction of N-methacryloyl-L-alanine and 1,4-diaminobutane. Proteinase K can specifically recognize and catalyze the hydrolytic cleavage of these peptide bonds. When these peptide bonds, which serve as network cross-linking points, are cleaved, the integrity of the polymer network is disrupted, leading to network structure disintegration, material degradation, and macroscopic mass loss.

[0057] Comparative Example 1 uses conventional ethylene glycol dimethacrylate as a crosslinking agent, whose molecular structure does not contain peptide bonds that can be recognized and hydrolyzed by proteinase K. Therefore, its crosslinked network structure remains stable and does not degrade in the same enzyme solution environment. The performance comparison between the examples and Comparative Example 1 confirms that this technical solution, by introducing a crosslinking agent containing specific peptide bonds, enables acrylic sheets to acquire the characteristic of programmed degradation under specific biological enzyme environments.

[0058] Test Example 4: Thermal Remodeling and Repair Performance Test Experimental steps: (a) Hot-reforming performance test: The sheet metal samples obtained in Example 1 and Comparative Example 2 were cut into small pieces. 5g of each piece was weighed and laid flat in a 100mm × 100mm × 2mm metal mold. The mold was placed on a flat vulcanizing machine and hot-pressed at 120°C and 10MPa for 20 minutes. After hot pressing, the mold was cooled to room temperature while maintaining pressure, and the reshaped sheet metal was removed.

[0059] The reshaped sheet was processed into tensile test specimens according to the method in Test Example 1, and its tensile strength was tested. The tensile strength recovery rate was calculated according to the formula: Tensile strength recovery rate (%) = (Tensile strength of the reshaped specimen / Tensile strength of the original specimen) × 100.

[0060] (b) Heat Repair Performance Test: The plate samples prepared in Example 1 and Comparative Example 2 were cut into 20mm × 10mm × 2mm blocks. A scalpel blade was used to make a scratch that runs through the width of the block at the center of the block surface.

[0061] The depth of the scratch before heat treatment was measured using a probe profilometer and recorded as follows: Subsequently, the scratched sample was placed in an oven at 110°C and heated for 30 minutes. After removing the sample and cooling to room temperature, the depth of the scratch was measured again at the same location using a probe profilometer, and recorded as follows. According to the formula: Repair efficiency (%) = Calculate the repair efficiency of scratches.

[0062] Experimental data: Table 4. Test results of heat remodeling and repair performance of each embodiment and comparative example. Sample number Tensile strength recovery rate (%) Repair efficiency (%) Example 1 88.7 94.2 Example 2 85.1 92.5 Example 3 90.3 95.8 Comparative Example 2 Incomplete sample block not formed 2.7 The test data in Table 4 show that the samples in Examples 1-3, after being crushed and hot-pressed, were able to reform into complete sheets, and their tensile strength recovery rates were all above 85%. Furthermore, after heat treatment, the repair efficiency of their surface scratches was all above 92%. In contrast, the fragments of the sample in Comparative Example 2 failed to fuse into a complete sample under the same hot-pressing conditions, and the depth of its surface scratches remained essentially unchanged after heat treatment, resulting in extremely low repair efficiency.

[0063] The thermoremodeling and repair capabilities of materials originate from the dynamic and reversible borate ester crosslinking network within the polymer network. This network is formed by the reaction of the vicinal diol structure of 2-hydroxyethyl methacrylate units with 1,4-phenylenediboric acid. Under external thermal stimulation (e.g., 110-120°C), the borate ester bonds undergo reversible breakage and rearrangement. This dynamic bond exchange reaction endows polymer segments with the ability to rearrange and move within the crosslinking network, thereby giving the material macroscopic flowability and enabling the fusion and remodeling of fragments as well as scratch healing.

[0064] The sample in Comparative Example 2, because it did not contain 1,4-phenylenediboric acid during preparation, had a polymer network consisting solely of irreversible covalent bonds, classifying it as a permanent cross-linked network. This static network structure restricts the movement of polymer chain segments, preventing macroscopic flow even at high temperatures, and therefore lacks the ability to reshape and repair itself. The performance difference between the examples and Comparative Example 2 directly confirms that this technical solution, by constructing a dynamic borate ester cross-linked network, endows the material with the functions of thermal reshaping and damage repair.

Claims

1. An innovative preparation method for an environmentally friendly biodegradable acrylic sheet, characterized in that, Includes the following steps: (a) Preparation of prepolymer syrup: The raw material components are mixed evenly and prepolymerized under light to obtain a prepolymer syrup with a viscosity of 800-1200 mPa·s; The raw material components, by weight, include: 70-80 parts of methyl methacrylate; 15-25 parts of autocatalytic precursor functionalized furfural-derived lactone; 1-3 parts of 2-hydroxyethyl methacrylate; 1-3 parts of enzyme-responsive diene crosslinking agent; Photoinitiator 0.2-0.5 parts; (b) Casting and dynamic network construction: 1,4-phenylenediboric acid is added to the prepolymer syrup, mixed evenly, and then cast into a mold and heated at 80-95°C for 2.5-3.5 hours to form a dynamic and reversible borate ester crosslinking network; (c) Final curing and annealing: The product obtained in step (b) is cured by light, then demolded and annealed to obtain the environmentally friendly biodegradable acrylic sheet.

2. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, The preparation method of the autocatalytic precursor functionalized furfural-derived lactone includes the following steps: 5-Hydroxymethylfurfural was reacted with acetic anhydride in a molar ratio of 1:(1.2-1.5) to acetylate and protect the hydroxyl group, yielding 5-(acetoxymethyl)furfural. Next, the 5-(acetoxymethyl)furfural was reacted with sodium borohydride at a molar ratio of 1:(1.0-1.2) to reduce the aldehyde group to a hydroxyl group, yielding [5-(acetoxymethyl)furan-2-yl]methanol; Then, at 0-5℃, using rose red as a photosensitizer, the [5-(acetoxymethyl)furan-2-yl]methanol was subjected to photo-oxidation reaction using a light source with a wavelength of 520-550nm to construct a lactone ring and obtain the lactone product; Finally, the lactone product, methacryloyl chloride, and triethylamine were reacted in a molar ratio of 1:(1.2-1.5):(1.5-2.0) to introduce a polymer double bond, thus preparing the autocatalytic precursor functionalized furfural-derived lactone.

3. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, The preparation method of the enzyme-responsive diene crosslinking agent includes: Using 1,4-diaminobutane, N-methacryloyl-L-alanine, EDC·HCl and HOBt as raw materials, an amidation reaction was carried out at a molar ratio of 1:(2.2-2.5):(2.5-3.0):(2.5-3.0) to obtain an enzyme-responsive diene crosslinking agent.

4. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, The photoinitiator is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

5. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, The photopolymerization described in step (a) uses an LED light source with a wavelength of 395-405nm and is carried out at a temperature of 30-40℃.

6. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, In step (b), the molar ratio of 1,4-phenylenediboric acid to 2-hydroxyethyl methacrylate is from 0.9:2 to 1.05:

2.

7. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, In step (b), after adding the 1,4-phenylenediboric acid and before pouring it into the mold, the prepolymer syrup containing 1,4-phenylenediboric acid is further stirred and degassed under a vacuum of -0.08 to -0.09 MPa.

8. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, The photocuring in step (c) uses an LED light source with a wavelength of 395-405nm, and the two sides are alternately irradiated for 30-45 minutes.

9. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, In step (c), the annealing process is as follows: the temperature is raised from room temperature to 105-115℃ at a rate of 3-5℃ / min, held at a constant temperature for 1.5-2.5 hours, and then slowly cooled to below 40℃ at a rate of 1-2℃ / min.

10. The innovative preparation method of an environmentally friendly biodegradable acrylic sheet according to claim 1, characterized in that, In step (a), the raw material components further include 0.1-0.5 parts of a chain transfer agent, wherein the chain transfer agent is dodecyl mercaptan.