A biodegradable thin film material and its preparation method

Abstract

This invention discloses a biodegradable thin film material and its preparation method. The preparation method includes the following steps: mixing a gelling agent, a first organic solvent, and a second organic solvent, heating and stirring the mixture, pouring it into a mold, cooling it at room temperature for a preset time, and then evaporating the first organic solvent at a preset temperature to obtain the biodegradable thin film material. The gelling agent has the following structural formula: R1 is a side chain group attached to the central carbon atom of an amino acid, excluding the amino group, carboxyl group, and one hydrogen atom; R2 is an alkyl group with 16-19 carbon atoms; R3 is 9-fluorenylmethoxycarbonyl or tert-butoxycarbonyl; the boiling point of the second organic solvent is higher than that of the first organic solvent, and the second organic solvent does not form an azeotrope with the first organic solvent. This method can prepare large-size, defect-free, high-strength, biodegradable, and plasticizable hydrophobic thin film materials.

Description

Technical Field

[0001] This invention relates to the field of biodegradable thin film materials technology, and in particular to a biodegradable thin film material and its preparation method. Background Technology

[0002] With the rapid development of the plastics industry, the application of plastic products has penetrated every corner of society, from industrial production to clothing, food, housing, and transportation. Plastic products are ubiquitous, especially plastic bags, which permeate all aspects of people's lives. However, because most plastic bags used in daily life are structurally stable and not easily degraded, they seriously harm the ecological environment and threaten human health. Currently, many biodegradable film materials have been researched and prepared, such as starch-based plastics, polylactic acid (PLA), polyhydroxyalkanoates (PHA), and polybutylene adipate / terephthalate (PBAT). However, these materials have not truly replaced traditional plastics due to certain defects in their structural properties, low strength, or high production costs. Therefore, the preparation of biodegradable film materials remains a significant technical challenge.

[0003] Supramolecular gel film materials formed by the self-assembly of small molecule gel agents hold promise as a replacement for traditional packaging film materials due to their excellent biodegradability, safety, economy, and practicality. Although these materials are easily degraded through various methods, they are generally soft materials, often exhibiting low mechanical strength and lacking practical value, thus failing to replace traditional plastics.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a biodegradable thin film material and its preparation method, aiming to solve the problem of low mechanical strength of existing thin film materials formed by self-assembly using small molecule gelling agents.

[0006] The technical solution of the present invention is as follows:

[0007] A first aspect of the present invention provides a method for preparing a biodegradable thin film material, comprising the steps of:

[0008] After mixing the gelling agent, the first organic solvent, and the second organic solvent, the mixture is heated and stirred, poured into a mold, cooled at room temperature for a preset time, and then the first organic solvent is evaporated at a preset temperature to obtain the biodegradable film material.

[0009] The structural formula of the gelling factor is as follows:

[0010]

[0011] R1 is a side chain group attached to the central carbon atom of an amino acid, excluding the amino group, carboxyl group, and one hydrogen atom. The amino acid is selected from one of the following: glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, and pyrrolidone.

[0012] R2 is an alkyl group having 16 to 19 carbon atoms;

[0013] R3 is 9-fluorenylmethoxycarbonyl or tert-butyloxycarbonyl;

[0014] The boiling point of the second organic solvent is higher than that of the first organic solvent, and the second organic solvent does not form an azeotrope with the first organic solvent.

[0015] Optionally, the first organic solvent is a liquid alkane solvent with fewer than 9 carbon atoms.

[0016] Optionally, the first organic solvent includes at least one of n-pentane, n-hexane, n-heptane, and n-octane.

[0017] Optionally, the second organic solvent includes at least one of phytane, squalane, squalene, white oil, silicone oil, vegetable oil, polyalphaolefin synthetic oil, and hexadecane.

[0018] Optionally, the mass ratio of the gelling agent, the first organic solvent, and the second organic solvent is 1–9:30–300:9–91.

[0019] Optionally, the material is heated and stirred at a temperature of 100–250°C, poured into a mold, cooled to room temperature for 10–20 minutes, and then the first organic solvent is evaporated at a temperature of 40–90°C for 3–24 hours to obtain the biodegradable film material.

[0020] Optionally, the method for preparing the gelling factor includes the following steps:

[0021] supply R2-NH2;

[0022] Will R2-NH2, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloric acid, 1-hydroxybenzotriazole, and a third organic solvent were mixed and stirred to obtain the crude product.

[0023] The crude product was purified to obtain the gelling factor.

[0024] Optionally, the stirring reaction is carried out under the following conditions: stirring reaction at room temperature for 3 to 7 days.

[0025] Optionally, the step of purifying the crude product to obtain the gelling factor specifically includes:

[0026] The crude product was washed with a mixture of ethanol and water, then recrystallized with ethyl acetate and dried to obtain the gelling agent.

[0027] In a second aspect, the present invention provides a biodegradable thin film material, wherein it is prepared by the preparation method of the present invention as described above.

[0028] Beneficial Effects: The gelling agent described in this invention possesses hydrophobic long alkyl tail chains, enabling it to spontaneously aggregate and assemble into a three-dimensional network structure through hydrogen bonds, π-π interactions, and hydrophobic forces. Specifically, through a bottom-up self-assembly strategy, the self-assembled nanofibers formed by physical cross-linking can effectively immobilize both low-boiling-point and high-boiling-point organic solvents, forming a supramolecular gel. Then, by removing the low-boiling-point organic solvent, large-size, defect-free, high-strength, biodegradable, and plasticizable hydrophobic thin film materials are prepared, solving the problem of low mechanical properties in existing thin film materials obtained through self-assembly using small-molecule gelling agents. The preparation method provided by this invention uses readily available and inexpensive raw materials, and the preparation process is simple. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the formation of a biodegradable thin film material in an embodiment of the present invention.

[0030] Figure 2 The image shows the 1H NMR spectrum of the gel factor prepared in Example 1 of this invention.

[0031] Figure 3 (a) is a physical image of the biodegradable film material in Example 2 of the present invention, (b) is a physical image of the biodegradable film material in Example 3 of the present invention, (c) is a physical image of the biodegradable film material in Example 4 of the present invention, and (d) is a physical image of the biodegradable film material in Example 5 of the present invention.

[0032] Figure 4 This is a physical image of the biodegradable thin film material with a thickness of 450 μm in Example 7 of the present invention.

[0033] Figure 5 The image shows the load-bearing test results of the 450 μm thick biodegradable film material in Example 7 of this invention.

[0034] Figure 6 The figures show the tensile properties of the biodegradable film materials with a thickness of 450 μm in Examples 6 and 7 of this invention.

[0035] Figure 7 This is a diagram showing the rollability of a 1 mm thick biodegradable film material in Example 7 of the present invention.

[0036] Figure 8 This is a diagram showing the foldability of a 1 mm thick biodegradable film material in Example 7 of the present invention.

[0037] Figure 9 This is a diagram showing the solubility of the 2mm thick biodegradable film material in different solutions in Example 7 of the present invention. Detailed Implementation

[0038] This invention provides a biodegradable thin film material and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0040] The inventors discovered through research that while gels formed by small molecule gelling agents (i.e., small molecule gelling agents) are ideal candidates for preparing biodegradable film materials, the preparation of high-strength films using small molecule gelling agents faces a contradiction: theoretically, the higher the gel concentration when the gelling agent forms a gel, the better the mechanical properties of the resulting gel; however, experimental tests have shown that the better the solubility of the gelling agent in the solvent, the worse the mechanical properties of the gel. This result greatly limits the use of small molecule gelling agents in preparing high-strength films. Based on this, this invention proposes a new method for preparing biodegradable film materials by adjusting the solvent composition and using small molecule gelling agents with specific structures. This method overcomes the above contradiction, and the film material prepared by this method can simultaneously possess high strength and biodegradability. Specifically, the preparation method of the biodegradable film material includes the following steps: mixing a gelling agent, a first organic solvent, and a second organic solvent, heating and stirring, pouring the mixture into a mold, cooling it at room temperature for a preset time, and then evaporating the first organic solvent at a preset temperature to obtain the biodegradable film material.

[0041] The structural formula of the gelling factor is as follows:

[0042]

[0043] R1 is a side chain group attached to the central carbon atom of an amino acid, excluding the amino group, carboxyl group, and one hydrogen atom. The amino acid is selected from one of the following: glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, and pyrrolidone.

[0044] R2 is an alkyl group having 16 to 19 carbon atoms;

[0045] R3 is 9-fluorenylmethoxycarbonyl or tert-butyloxycarbonyl;

[0046] The boiling point of the second organic solvent is higher than that of the first organic solvent, and the second organic solvent does not form an azeotrope with the first organic solvent.

[0047] As is well known, the general structural formula of amino acids is R refers to the side chain group attached to the central carbon atom of an amino acid, excluding the amino group, carboxyl group, and one hydrogen atom. Different R side chain groups determine different types of amino acids. For example, in this embodiment, when the amino acid is glycine, R1 is -H; when the amino acid is alanine, R1 is -CH3; when the amino acid is valine, R1 is -CH(CH3)2; and when the amino acid is methionine, R1 is... When the amino acid is phenylalanine, then R1 is When the amino acid is threonine, then R1 is When the amino acid is aspartic acid, then R1 is And so on. Among them, Indicates the connection site.

[0048] R2 is an alkyl group having 16 to 19 carbon atoms; specifically, it can be a straight-chain alkyl group having 16 to 19 carbon atoms, such as -C 16 H 33 -C 17 H 35 -C 18 H 37 -C 19 H 39 wait.

[0049] In this embodiment of the invention, the gel factor of the structure is degradable and has low solubility in the second organic solvent (high boiling point). This embodiment, by mixing the first organic solvent (low boiling point) and the second organic solvent (high boiling point), forms a mixed solvent system of low-boiling-point and high-boiling-point solvents, which can improve the solubility of the gel factor by up to ten times, significantly increasing the solubility of the gel factor. In this embodiment, the gel factor of the structure obtained through molecular design, i.e., an amino acid derivative, has a molecular weight of less than 600, a length of approximately 2-3 nm, and a hydrophobic long alkyl tail chain. It can spontaneously aggregate and assemble into a three-dimensional network structure through a bottom-up self-assembly strategy via hydrogen bonds, π-π interactions, and hydrophobic forces, such as... Figure 1 As shown, the gel factor forms ultrafine fibers with a width of 2-3 nm during self-assembly. These ultrafine fibers then undergo helical cross-linking to form a cross-linked network structure. This allows the self-assembled nanofibers formed through physical cross-linking to effectively fix the first and second organic solvents to form a supramolecular gel. At this point, the supramolecular gel is a soft substance with low strength. Furthermore, after removing the first organic solvent (low boiling point) through evaporation, the network structure formed between the ultrafine fibers becomes more compact, and the mechanical properties are significantly improved. This solves the problem of low mechanical properties in existing thin film materials assembled by small molecule gel factors.

[0050] In this embodiment, a low-boiling-point organic solvent and a high-boiling-point organic solvent are mixed and immobilized through the self-assembly of the gelation factor in the structure described above to prepare a supramolecular gel. Then, by removing the low-boiling-point organic solvent, a large-size, defect-free, high-strength, biodegradable, and plasticizable hydrophobic thin film material is obtained. The preparation method provided by this embodiment uses readily available raw materials, is low in cost, and has a simple preparation process. Furthermore, this embodiment can achieve the preparation of high-strength biodegradable thin film materials under conditions of low gelation factor concentration.

[0051] In this embodiment, the boiling point of the second organic solvent is greater than that of the first organic solvent, and the second organic solvent does not form an azeotrope with the first organic solvent. This allows the first organic solvent to evaporate while the second organic solvent does not evaporate at a preset temperature.

[0052] In some embodiments, the first organic solvent is a liquid alkane solvent with fewer than 9 carbon atoms.

[0053] In some embodiments, the first organic solvent includes, but is not limited to, at least one of n-pentane, n-hexane, n-heptane, and n-octane.

[0054] In some embodiments, the second organic solvent includes at least one selected from phytane, squalane, squalene, white oil, silicone oil, vegetable oil (e.g., sunflower seed oil), polyalphaolefin synthetic oil, and hexadecane. Polyalphaolefin synthetic oil is a class of long-chain alkanes obtained by polymerizing polyalphaolefins (mainly C8-C10 fractions) under the action of a catalyst (mainly trimers, tetramers, and pentamers). In some specific embodiments, the polyalphaolefin synthetic oil is PAO4 to PAO150 synthetic oil, such as PAO4, PAO8, PAO100, PAO150, etc. In a further embodiment, the second organic solvent has a boiling point of not less than 100°C, i.e., an organic solvent with a boiling point of not less than 100°C is selected from phytane, squalane, squalene, white oil, silicone oil, vegetable oil (e.g., sunflower seed oil), polyalphaolefin synthetic oil, and hexadecane.

[0055] In this invention, the first organic solvent and the second organic solvent can be miscible in any proportion, which can be set according to actual needs, and the amount of gelling agent added can also be set according to actual needs. For example, in some embodiments, the mass ratio of the gelling agent, the first organic solvent, and the second organic solvent is 1–9:30–300:9–91. For example, the mass ratio of the gelling agent, the first organic solvent, and the second organic solvent is 1:30:9, 4:150:50, 7:250:80, or 9:300:91, etc.

[0056] In some embodiments, the material is heated and stirred at a temperature of 100–250°C, poured into a mold, and cooled to room temperature for 10–20 minutes (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 minutes). Then, after evaporating the first organic solvent at a preset temperature, the biodegradable film material is obtained. For example, the heating and stirring temperature can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C. The temperature and time for evaporating the first organic solvent can be set according to actual needs, with the goal of completely evaporating the first organic solvent. For example, the first organic solvent is volatilized at a temperature of 40 to 90°C for 3 to 24 hours. The specific temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, or 90°C, and the specific time can be 3 hours, 4 hours, 5 hours, 8 hours, 10 hours, 15 hours, 20 hours, or 24 hours.

[0057] In some embodiments, the method for preparing the gelling factor includes the following steps:

[0058] supply R2-NH2;

[0059] Will R2-NH2, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloric acid (EDC·HCl), 1-hydroxybenzotriazole (HOBt), and a third organic solvent were mixed and stirred to obtain the crude product.

[0060] After purifying the crude product, the gelling factor is obtained, wherein the groups represented by R3 and R1 are the same as those mentioned above, and will not be repeated here.

[0061] In this embodiment, the amino acid with the N-terminal protecting group R3 is... The gelling agent is obtained by reacting fatty amine R2-NH2, condensing agent EDC·HCl and HOBt. At the same time, the combined use of EDC·HCl and HOBt can effectively control side reactions, and HOBt can also prevent racemization during the synthesis process.

[0062] In some embodiments, the third organic solvent includes, but is not limited to, at least one of dichloromethane, toluene, n-hexane, and n-octane. Preferably, the third organic solvent is dichloromethane, in which the reactants have the highest solubility.

[0063] In some embodiments, the stirring reaction is carried out at room temperature for 3 to 7 days, for example, 3, 4, 5, 6 or 7 days. Unless otherwise specified, 1 day in this invention represents 24 hours.

[0064] In some embodiments, the step of purifying the crude product to obtain the gelling factor specifically includes:

[0065] The crude product was washed with a mixture of ethanol and water (to remove unreacted condensing agents, amino acids with N-terminal protecting groups R3, and fatty amines), then recrystallized with ethyl acetate and dried to obtain the gelling agent.

[0066] In this embodiment, since the gelling agent is insoluble in a mixture of ethanol and water, the target product can be obtained by filtration after washing the crude product with a mixture of ethanol and water.

[0067] This invention also provides a biodegradable thin film material, prepared using the method described above. The biodegradable thin film material contains 10-90% by mass, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%. This invention enables the preparation of biodegradable thin film materials with varying concentrations of gelling agents (from low to high concentrations).

[0068] The following detailed description uses specific examples.

[0069] Example 1

[0070] Unless otherwise specified, all raw materials used in the following examples are commercially available products. PAO8 was purchased from Shenzhen Huashengyuan Petroleum Technology Co., Ltd., PAO150 was purchased from Shenzhen Huashengyuan Petroleum Technology Co., Ltd. (produced by Sinopec), and Fmoc-L-phenylalanine was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with the grade F105472.

[0071] This embodiment provides a method for preparing a gelling factor, comprising the following steps:

[0072] 2g of Fmoc-L-phenylalanine 1.67 g of octadecylamine, 0.96 g of EDC·HCl, and 0.84 g of 1-hydroxybenzotriazole monohydrate were added to a round-bottom flask, and 125 mL of dichloromethane was added as a solvent. The mixture was stirred thoroughly at room temperature and reacted for 3 days.

[0073] The solvent was removed from the reaction product by rotary evaporation. 200 mL of a 1:1 volume ratio of ethanol / water mixed solvent was added, and the mixture was heated and stirred until boiling. The mixture was filtered while hot, and the residue was collected. A 3:7 volume ratio of ethanol / water mixed solvent (100 mL of ethanol and 234 mL of water) was added. The above operation was repeated 3 times to obtain the crude gelling agent.

[0074] Add 400 mL of dichloromethane to the crude gelling agent described above, heat to dissolve until the solution is clear, filter while hot, and collect the filtrate. Cool the filtrate to room temperature and perform rotary evaporation.

[0075] The product obtained after rotary evaporation was recrystallized twice with ethyl acetate and finally dried under vacuum to obtain the final product, gelling agent. Designated as L-FPC18, it is a white solid powder, and its 1H NMR spectrum is as follows: Figure 2 As shown.

[0076] Example 2

[0077] This embodiment provides a method for preparing a biodegradable thin film material, including the following steps:

[0078] L-FPC18, n-octane, and squalane from Example 1 were mixed in a mass ratio of 1:30:9. The mixture was heated and stirred at 180°C until L-FPC18 was completely dissolved. After the solution became clear, it was poured into a mold and cooled at room temperature for 10 minutes to form a stable gel. The gel was then placed in a forced-air drying oven to volatilize the n-octane. The volatilization was carried out at 80°C for 3 hours to obtain a biodegradable film material.

[0079] Example 3

[0080] This embodiment provides a method for preparing a biodegradable thin film material, which differs from Embodiment 2 only in that squalane is replaced with sunflower seed oil.

[0081] Example 4

[0082] This embodiment provides a method for preparing a biodegradable thin film material, which differs from Embodiment 2 only in that squalane is replaced with silicone oil.

[0083] Example 5

[0084] This embodiment provides a method for preparing a biodegradable thin film material, which differs from Embodiment 2 only in that squalane is replaced with PAO150.

[0085] Physical images of the biodegradable film materials in Examples 2-5 are shown below. Figure 3 As shown, these biodegradable film materials all have good formability.

[0086] Example 6

[0087] This embodiment provides a method for preparing a biodegradable thin film material, including the following steps:

[0088] L-FPC18, n-octane, and PAO8 from Example 1 were mixed at a mass ratio of 1:100:8.31. The mixture was heated and stirred at 220°C until L-FPC18 was completely dissolved. After the solution became clear, it was poured into a mold and cooled at room temperature for 10 minutes to form a stable gel. The gel was then placed in a forced-air drying oven to evaporate the n-octane at 80°C for 3 hours. By changing the amount of solution poured into the mold, biodegradable film materials with thicknesses of 450 μm, 1 mm, and 2 mm were obtained. The mass content of L-FPC18 in the biodegradable film materials was approximately 10% in all cases.

[0089] Example 7

[0090] This embodiment provides a method for preparing a biodegradable thin film material, including the following steps:

[0091] L-FPC18, n-octane, and PAO8 from Example 1 were mixed at a mass ratio of 1:100:4.18. The mixture was heated and stirred at 220°C until L-FPC18 was completely dissolved. After the solution became clear, it was poured into a mold and cooled at room temperature for 10 minutes to form a stable gel. The gel was then placed in a forced-air drying oven to evaporate the n-octane at 80°C for 3 hours. By varying the amount of solution poured into the mold, biodegradable film materials with thicknesses of 450 μm, 1 mm, and 2 mm were obtained. The mass content of L-FPC18 in the biodegradable films was approximately 20% in all cases. A physical image of the 450 μm thick biodegradable film material is shown below. Figure 4 As shown, the biodegradable film material has high transparency.

[0092] test:

[0093] The load-bearing test results of the 450 μm thick biodegradable film material in Example 7 are as follows: Figure 5 As shown, it can withstand a weight of approximately 450g and has high strength.

[0094] Tensile properties were tested on the 450 μm thick biodegradable film materials from Examples 6 and 7, and the results are as follows: Figure 6 As shown, the Young's modulus of the biodegradable film material with a thickness of 450 μm in Example 7 can reach 144 MPa, while the Young's modulus of commercially available parafilm is 150 MPa. The biodegradable film material prepared according to the method provided in this invention has excellent tensile strength, which is almost comparable to that of parafilm.

[0095] like Figure 7 As shown, the 1 mm thick biodegradable film material in Example 7 exhibits excellent rollability. Biodegradable film materials of other thicknesses in Example 7, as well as biodegradable materials of different thicknesses in Example 6, also exhibit similar properties.

[0096] like Figure 8 As shown, the 1 mm thick biodegradable film material in Example 7 exhibits excellent foldability. Biodegradable film materials of other thicknesses in Example 7, as well as biodegradable film materials of different thicknesses in Example 6, also exhibit similar properties.

[0097] The 2mm thick biodegradable film material from Example 7 was cut into four strips of the same size and immersed in water, ethanol, chloroform, and pepsin solution, respectively, and placed under the same conditions. Figure 9 As shown, significant changes occurred after 15 minutes. The biodegradable film material showed almost no significant change in water, swelled in ethanol, and the portion immersed in chloroform was decomposed. The gel thickness decreased significantly in pepsin. This indicates that the film material can be slowly degraded in pepsin and completely degraded in chloroform within a short time, demonstrating its biodegradability.

[0098] In summary, this invention provides a biodegradable thin film material and its preparation method. The gel factor of the structure described in this invention has hydrophobic long alkyl tail chains, which can spontaneously aggregate and assemble into a three-dimensional network structure through hydrogen bonds, π-π interactions, and hydrophobic forces. Specifically, through a bottom-up self-assembly strategy, the self-assembled nanofibers formed by physical cross-linking can effectively fix low-boiling-point organic solvents and high-boiling-point organic solvents to form a supramolecular gel. Then, by removing the low-boiling-point organic solvent, a large-size, defect-free, high-strength, biodegradable, and plasticizable hydrophobic thin film is prepared, solving the problem of low mechanical properties of existing thin film materials assembled by small-molecule gel factors. The preparation method provided by this invention uses readily available raw materials, is inexpensive, and has a simple preparation process.

[0099] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a biodegradable thin film material, characterized in that, Including the following steps: After mixing the gelling agent, the first organic solvent, and the second organic solvent, the mixture is heated and stirred, poured into a mold, cooled at room temperature for a preset time, and then the first organic solvent is evaporated at a preset temperature to obtain the biodegradable film material. The structural formula of the gelling factor is as follows: ， R1 is a side chain group attached to the central carbon atom of an amino acid, excluding the amino group, carboxyl group, and one hydrogen atom. The amino acid is selected from one of the following: glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, and pyrrolidone. R2 is an alkyl group having 16 to 19 carbon atoms; R3 is 9-fluorenylmethoxycarbonyl or tert-butyloxycarbonyl; The boiling point of the second organic solvent is higher than that of the first organic solvent, and the second organic solvent does not form an azeotrope with the first organic solvent; The first organic solvent is a liquid alkane solvent with fewer than 9 carbon atoms; The second organic solvent includes at least one of phytane, squalane, squalene, white oil, silicone oil, vegetable oil, polyalphaolefin synthetic oil, and hexadecane.

2. The preparation method according to claim 1, characterized in that, The first organic solvent includes at least one of n-pentane, n-hexane, n-heptane, and n-octane.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the gelling agent, the first organic solvent, and the second organic solvent is 1~9:30~300:9~91.

4. The preparation method according to claim 1, characterized in that, The mixture is heated and stirred at 100~250℃, poured into a mold, cooled to room temperature for 10~20 min, and the first organic solvent is evaporated at 40~90℃ for 3~24 h to obtain the biodegradable film material.

5. The preparation method according to claim 1, characterized in that, The preparation method of the gelling factor includes the following steps: supply R2-NH2; Will R2-NH2, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloric acid, 1-hydroxybenzotriazole, and a third organic solvent were mixed and stirred to obtain the crude product. The crude product was purified to obtain the gelling factor.

6. The preparation method according to claim 5, characterized in that, The stirring reaction was carried out at room temperature for 3 to 7 days.

7. The preparation method according to claim 5, characterized in that, The specific steps for purifying the crude product to obtain the gelling factor include: The crude product was washed with a mixture of ethanol and water, then recrystallized with ethyl acetate and dried to obtain the gelling agent.

8. A biodegradable thin film material, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

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