PBS-based supramolecular degradable plastic and preparation method thereof

Abstract

The invention discloses a PBS-based supramolecular degradable plastic and a preparation method thereof, and relates to a degradable plastic and a preparation method thereof. The invention aims to solve the problems that the existing PBS degradable plastic is slowly degraded in soil and water, especially seawater, and the glass-transition temperature and the strength of the PBS degradable plastic are low. The degradable plastic is prepared from the PBS and the starch. The preparation method comprises the following steps: firstly, synthesizing a PBS oligomer with a relatively low molecular weight, and modifying the PBS oligomer so that PBS-CHO is terminated by an aldehyde group of the PBS oligomer; secondly, performing oxidation treatment on the starch by using sodium periodate to prepare aldehyde starch S-CHO with different aldehyde degrees; and finally, carrying out imine condensation by using different amines, PBS-CHO and S-CHO to prepare the PBS-based supramolecular degradable plastic. Compared with biodegradable plastics PBS and PLA, the PBS-based supramolecular degradable plastic prepared by the preparation method disclosed by the invention has a higher degradation rate. According to the invention, the PBS-based supramolecular degradable plastic can be obtained.

Description

Technical Field

[0001] The invention relates to a degradable plastic and a preparation method thereof. Background Art

[0002] At present, plastic production is about 9 billion tons, and about 63 tons of plastic waste are generated, causing serious environmental pollution. In order to alleviate the pressure of plastic waste pollution, it is urgent to develop new degradable plastics with excellent performance. However, the current biodegradable plastics only have good degradation performance under high-temperature composting conditions. For example, polylactic acid (PLA) can be degraded in 6 to 24 months under composting conditions, and polybutylene succinate (PBS) can be degraded in 6 to 12 months under composting conditions. However, in ordinary mitigation, the degradation in soil, river water, and seawater is very slow, especially in high-salt, low-temperature, and low-bacteria seawater environments. The degradation weight loss of PBS polyester in 12 months is less than 5%.

[0003] Adding flexible, hydrophilic and degradable segments can increase the degradation rate of PBS in seawater, but the thermal and mechanical properties of PBS decrease significantly, making it difficult to use as plastic. Therefore, the preparation of high-strength, fast-degrading PBS-based plastics remains a huge challenge. Starch has good degradation ability in the natural environment and has a good degradation rate in various water bodies and soils, but the bridge ring structure of its molecular chain and the strong force of polyhydroxy hydrogen bonds make it difficult to process and it is impossible to prepare plastics with excellent performance. How to use starch to prepare plastics is also one of the hot spots that need to be broken through. Summary of the invention

[0004] The purpose of the present invention is to solve the problems that the existing PBS degradable plastics degrade slowly in soil and water, especially in seawater, and the PBS degradable plastics have low glass transition temperature and low strength, and to provide a PBS-based supramolecular degradable plastic and a preparation method thereof.

[0005] The invention uses PBS and starch to prepare a degradable plastic. First, a low molecular weight PBS oligomer is synthesized and modified to obtain aldehyde-terminated PBS-CHO; second, the starch is oxidized with sodium periodate to prepare aldehyde starch S-CHO with different aldehyde degrees; finally, different amines, PBS-CHO and S-CHO are used to perform imine condensation to prepare PBS-based supramolecular degradable plastic.

[0006] The structural formula of a PBS-based supramolecular degradable plastic is:

[0007] The value range of n is 10≤n≤100.

[0008] A method for preparing a PBS-based supramolecular degradable plastic is specifically completed by the following steps:

[0009] 1. Preparation of low molecular weight PBS oligomers by melt polycondensation:

[0010] Firstly, succinic acid, butanediol and tetrabutyl titanate are added into a three-necked flask, reacted at 160°C to 190°C for a period of time, then vacuumed to 10Pa to 100Pa, then heated to 220°C to 230°C for a period of time, and finally cooled to room temperature to obtain a low molecular weight PBS oligomer;

[0011] 2. Preparation of PBS-CHO by terminal aldehyde modification of PBS oligomers:

[0012] A low molecular weight PBS oligomer, 4-formylbenzoic acid, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are added to chloroform, and the mixture is condensed and refluxed at 40°C to 60°C for a period of time. After the reaction is completed, the mixture is cooled to room temperature, filtered to remove solids, and the filtrate is concentrated and dripped into methanol at 0°C to 4°C dropwise, and the solids are filtered out. The solids are then washed with methanol and ether at 0°C to 4°C for 3 to 5 times respectively, and finally dried in vacuum to obtain PBS-CHO;

[0013] 3. Oxidation of starch to S-CHO:

[0014] Dispersing starch in deionized water to form a suspension, adding sodium periodate at 20°C to 50°C, adjusting the pH value to 2 to 4, reacting for a period of time at 20°C to 50°C in the dark, centrifuging, and collecting solid products; washing the collected solid products, freeze-drying, and obtaining S-CHO;

[0015] 4. Preparation of PBS-based supramolecular degradable plastics:

[0016] PBS-CHO and S-CHO are added into chloroform, and stirred and dissolved at 40°C to 60°C to obtain a mixed solution; amine is added into the mixed solution, and reacted for a period of time by magnetic stirring to obtain a gel product; the gel product is washed, put into a fume hood to volatilize the solvent, and then vacuum dried to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer is pressed into a film, and then put into an oven at 90°C to 110°C for curing for a period of time to obtain a PBS-based supramolecular degradable plastic.

[0017] The PBS oligomer structural formula is:

[0018]

[0019] The PBS-CHO structural formula:

[0020]

[0021] The S-CHO structural formula:

[0022]

[0023] Principle of the present invention:

[0024] 1. First, a PBS oligomer with dihydroxyl end-capping is synthesized by melt polycondensation, and then a dialdehyde end-capping PBS oligomer is generated by esterification with 4-formylbenzoic acid;

[0025] 2. Sodium periodate as an oxidant can oxidize the two adjacent hydroxyl groups on C2 and C3 in the glucose unit of starch and convert it into dialdehyde starch;

[0026] 3. The aldehyde groups and amino groups in aldehyde-terminated PBS and dialdehyde starch undergo Schiff-base reaction to generate imines, which release small molecular water after condensation to generate PBS supramolecular plastics connected by imine bonds.

[0027] Advantages of the present invention:

[0028] 1. The imine in the PBS-based supramolecular degradable plastic prepared by the present invention is unstable in water and can be depolymerized in river water, sea water or trace water in soil to generate small molecular oligomers PBS and starch. PBS oligomers and starch are easily degraded in the natural environment. Therefore, the PBS-based supramolecular degradable plastic prepared by the present invention has a faster degradation rate than biodegradable plastics PBS and PLA;

[0029] 2. The PBS-based supramolecular degradable plastic prepared by the present invention has a higher glass transition temperature than PBS, and the material can be suitable for use in high temperature resistant degradable tableware;

[0030] 3. The PBS-based supramolecular degradable plastic prepared by the present invention can be chemically recycled by dissolving it in a hydrochloric acid aqueous solution to easily recover PBS oligomers and starch. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the NMR image of the low molecular weight PBS oligomer prepared in step 1 of Example 1;

[0032] Figure 2 This is the NMR of PBS-CHO prepared in step 2 of Example 1. DETAILED DESCRIPTION

[0033] Specific embodiment 1: This embodiment is a PBS-based supramolecular degradable plastic with a structural formula of:

[0034] The value range of n is 10≤n≤100.

[0035] Specific embodiment 2: This embodiment differs from the specific embodiment 1 in that: a method for preparing a PBS-based supramolecular degradable plastic is specifically completed in the following steps:

[0036] 1. Preparation of low molecular weight PBS oligomers by melt polycondensation:

[0037] Firstly, succinic acid, butanediol and tetrabutyl titanate are added into a three-necked flask, reacted at 160°C to 190°C for a period of time, then vacuumed to 10Pa to 100Pa, then heated to 220°C to 230°C for a period of time, and finally cooled to room temperature to obtain a low molecular weight PBS oligomer;

[0038] 2. Preparation of PBS-CHO by terminal aldehyde modification of PBS oligomers:

[0039] A low molecular weight PBS oligomer, 4-formylbenzoic acid, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are added to chloroform, and the mixture is condensed and refluxed at 40°C to 60°C for a period of time. After the reaction is completed, the mixture is cooled to room temperature, filtered to remove solids, and the filtrate is concentrated and dripped into methanol at 0°C to 4°C dropwise, and the solids are filtered out. The solids are then washed with methanol and ether at 0°C to 4°C for 3 to 5 times respectively, and finally dried in vacuum to obtain PBS-CHO;

[0040] 3. Oxidation of starch to S-CHO:

[0041] Dispersing starch in deionized water to form a suspension, adding sodium periodate at 20°C to 50°C, adjusting the pH value to 2 to 4, reacting for a period of time at 20°C to 50°C in the dark, centrifuging, and collecting solid products; washing the collected solid products, freeze-drying, and obtaining S-CHO;

[0042] 4. Preparation of PBS-based supramolecular degradable plastics:

[0043] PBS-CHO and S-CHO are added to chloroform, stirred and dissolved at 40°C to 60°C to obtain a mixed solution; amine is added to the mixed solution, and magnetic stirring is performed to react for a period of time to obtain a gel product; the gel product is washed, placed in a fume hood to volatilize the solvent, and then vacuum dried to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer is pressed into a film, and then placed in an oven at 90°C to 110°C for curing for a period of time to obtain a PBS-based supramolecular degradable plastic. The other steps are the same as those in the first embodiment.

[0044] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the mass ratio of succinic acid, butanediol and tetrabutyl titanate described in step 1 is (20g-100g):(17g-135g):(0.08g-0.4g). The other steps are the same as those of specific embodiment 1 or 2.

[0045] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: the reaction time at 160°C to 190°C in step 1 is 3h to 6h; the heating rate in step 1 is 5°C h -1 ~10℃h -1 ; The reaction time at 220°C to 230°C in step 1 is 10 min to 120 min. The other steps are the same as those in specific embodiments 1 to 3.

[0046] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the mass volume ratio of the low molecular weight PBS oligomer, 4-formylbenzoic acid, 4-dimethylaminopyridine, dicyclohexylcarbodiimide and chloroform described in step 2 is (2g-50g): (0.5g-3g): (0.05g-1g): (0.5g-5g): (60mL-100mL). The other steps are the same as those of specific embodiments 1 to 4.

[0047] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that: the time of the condensation reflux reaction at 40°C to 60°C in step 2 is 24h to 48h; the temperature of the vacuum drying in step 2 is 50°C to 80°C, and the time of the vacuum drying is 10h to 14h. The other steps are the same as those of specific embodiments 1 to 5.

[0048] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the volume ratio of starch, sodium periodate and deionized water in step 3 is (3g-5g):(3g-10g):(50mL-100mL). The other steps are the same as those of specific embodiments 1 to 6.

[0049] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that: in step three, the pH value is adjusted to 2 to 4 using dilute sulfuric acid with a mass fraction of 0.01 mol / L to 0.1 mol / L; in step three, the reaction time is 0.5 h to 12 h at 20°C to 50°C and protected from light; in step three, the collected solid product is washed 3 to 5 times with deionized water, and then freeze-dried at -10°C to -20°C for 12 h to 24 h. The other steps are the same as those of specific embodiments one to seven.

[0050] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: the amine described in step 4 is one or more of diethylenetriamine, hexamethylenediamine, octanediamine, decanediamine, 4,4-methylenebiscyclohexylamine and tris(2-aminoethyl)amine; the molar volume ratio of PBS-CHO, S-CHO and chloroform described in step 4 is (1mmol to 10mmol): (1mmol to 5mmol): 100mL; the molar ratio of the aldehyde group in PBS-CHO and S-CHO to the amine group in the amine described in step 4 is 1:1. The other steps are the same as specific embodiments 1 to 8.

[0051] Specific embodiment 10: The difference between this embodiment and specific embodiments 1 to 9 is that: the time of the magnetic stirring reaction described in step 4 is 8h to 12h; in step 4, the gel product is washed 3 to 5 times with anhydrous ethanol or methanol and placed in a fume hood to volatilize the solvent, and then vacuum dried at 50℃ to 70℃ for 12h to 24h to obtain a PBS-based supramolecular plastic prepolymer; in step 4, the PBS-based supramolecular plastic prepolymer is pressed at 80℃ to 100℃ and 10MPa to 30MPa for 5min to 60min to form a film; in step 4, the curing time in an oven at 90℃ to 110℃ is 12h to 24h. The other steps are the same as specific embodiments 1 to 9.

[0052] The following examples are used to verify the beneficial effects of the present invention:

[0053] Embodiment 1: A method for preparing a PBS-based supramolecular degradable plastic is specifically completed by the following steps:

[0054] 1. Preparation of low molecular weight PBS oligomers by melt polycondensation:

[0055] First, 25 g of succinic acid, 23 g of butanediol and 0.12 g of tetrabutyl titanate were added to a 500 mL three-necked flask and heated at 5 °C h -1 The temperature was raised to 190°C at a heating rate of 10°C / h, and the reaction was continued at 190°C for 4 h. The temperature was then evacuated to 30 Pa and then heated at a heating rate of 10°C / h. -1 The temperature was raised to 230° C. at a heating rate of 1.50° C., the mixture was reacted at 230° C. for 60 min, and finally the temperature was lowered to room temperature to obtain a low molecular weight PBS oligomer (weight average molecular weight of 2000 g / mol);

[0056] 2. Preparation of PBS-CHO by terminal aldehyde modification of PBS oligomers:

[0057] 2 g of low molecular weight PBS oligomer, 0.5 g of 4-formylbenzoic acid, 0.05 g of 4-dimethylaminopyridine (DMAP) and 0.5 g of dicyclohexylcarbodiimide (DCC) were added to 100 mL of chloroform, and the mixture was condensed and refluxed at 40°C for 48 h. After the reaction was completed, the mixture was cooled to room temperature, filtered to remove the solid, and the filtrate was concentrated and dripped into 0°C methanol dropwise, the solid was filtered out, and then washed with 0°C methanol and ether for 5 times respectively, and finally dried under vacuum at 80°C for 12 h to obtain PBS-CHO;

[0058] 3. Oxidation of starch to S-CHO:

[0059] 3 g of starch was dispersed in 100 mL of deionized water to form a suspension, and then 10 g of sodium periodate (NaIO4) was added at 40° C., and the pH value was adjusted to 3.5 using 0.01 mol / L dilute sulfuric acid, and the mixture was reacted at 40° C. and protected from light for 8 h, and then centrifuged to collect the solid product; the collected solid product was washed 5 times with deionized water, and then freeze-dried at -18° C. for 12 h to obtain S-CHO (the degree of starch aldehyde was 85%);

[0060] 4. Preparation of PBS-based supramolecular degradable plastics:

[0061] 2g PBS-CHO and 2g S-CHO were added into 100L chloroform, and the mixture was stirred and dissolved at 60°C to obtain a mixed solution; 1.24g diethylenetriamine was added dropwise into the mixed solution, and the mixture was reacted under magnetic stirring for 10h to obtain a gel product; the gel product was washed 5 times with anhydrous ethanol, placed in a fume hood to evaporate the solvent, and then vacuum dried at 70°C for 12h to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer was pressed at 100°C and 30MPa for 10min to form a film, and then placed in an oven at 90°C for curing for 12h to obtain a PBS-based supramolecular degradable plastic (S-PBS-1).

[0062] The structural formula of the PBS oligomer prepared in step 1 of Example 1 is:

[0063]

[0064] The structural formula of PBS-CHO prepared in step 2 of Example 1 is:

[0065]

[0066] The structural formula of S-CHO prepared in step 3 of Example 1 is:

[0067]

[0068] The structural formula of the PBS-based supramolecular degradable plastic prepared in Example 1 is:

[0069] Where n=20.

[0070] Embodiment 2: The difference between this embodiment and embodiment 1 is that: in step 4, 2g PBS-CHO and 4g S-CHO are added to 100L chloroform, stirred and dissolved at 60°C to obtain a mixed solution; 2.3g diethylenetriamine is added dropwise to the mixed solution, and the reaction is stirred magnetically for 10h to obtain a gel product; the gel product is washed 4 times with anhydrous ethanol, put into a fume hood to volatilize the solvent, and then vacuum dried at 70°C for 12h to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer is pressed at 90°C and 30MPa for 20min to form a film, and then put into a 90°C oven for curing for 12h to obtain a PBS-based supramolecular degradable plastic (S-PBS-2). The other steps and parameters are the same as those in embodiment 1.

[0071] Embodiment 3: The difference between this embodiment and embodiment 1 is that: in step 4, 4g PBS-CHO and 2g S-CHO are added to 100mL chloroform, stirred and dissolved at 40°C to obtain a mixed solution; 1.4g diethylenetriamine is added dropwise to the mixed solution, and the reaction is stirred magnetically for 12h to obtain a gel product; the gel product is washed 5 times with anhydrous ethanol, put into a fume hood to volatilize the solvent, and then vacuum dried at 70°C for 12h to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer is pressed at 80°C and 20MPa for 40min to form a film, and then put into an oven at 80°C for curing for 12h to obtain a PBS-based supramolecular degradable plastic (S-PBS-3). The other steps and parameters are the same as those in embodiment 1.

[0072] Embodiment 4: The difference between this embodiment and embodiment 1 is that: in step 4, 2g PBS-CHO and 2g S-CHO are added to 100mL chloroform, stirred and dissolved at 40°C to obtain a mixed solution; 1.4g tris(2-aminoethyl)amine is added dropwise to the mixed solution, and the reaction is stirred magnetically for 10h to obtain a gel product; the gel product is washed 5 times with anhydrous ethanol, put into a fume hood to volatilize the solvent, and then vacuum dried at 50°C for 20h to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer is pressed at 100°C and 30MPa for 40min to form a film, and then put into a 100°C oven for curing for 20h to obtain a PBS-based supramolecular degradable plastic (S-PBS-4). The other steps and parameters are the same as those in embodiment 1.

[0073] Comparative Example 1: 20 g of succinic acid and 22 g of butanediol were placed in a three-necked flask with a stirrer, 0.4 g of tetrabutyl titanate was added, nitrogen was introduced, and the mixture was reacted at 190 ° C for 7 h, and then vacuumed for polycondensation reaction, the vacuum degree was <20 Pa, and then the reaction temperature was 230 ° C for 8 h to obtain polybutylene succinate (PBS) with a weight average molecular weight of 2x10 4 g / mol).

[0074] Figure 1 This is the NMR image of the low molecular weight PBS oligomer prepared in step 1 of Example 1;

[0075] from Figure 1 It can be seen that: a is the peak of the methylene group of succinic acid in PBS, b and c are the peaks of the methylene group in butanediol, and d is the peak of the capped hydroxyl group, indicating that PBS oligomers are prepared.

[0076] Figure 2 This is the NMR of PBS-CHO prepared in step 2 of Example 1;

[0077] from Figure 2 It can be seen that a is the characteristic peak of hydrogen in the benzene ring of 4-formylbenzoic acid, and b is the characteristic peak of the aldehyde group. Figure 1 The d peak in the graph disappears, indicating that PBS-CHO material is prepared.

[0078] The PBS-based supramolecular degradable plastics in Examples 1-4 and the polybutylene succinate (PBS) prepared in Comparative Example 1 were prepared into standard specimens according to the requirements of GB / T 1040.1-2006, and then performance tests were performed.

[0079] Tensile performance test: measured according to GB / T 1040.1-2006, tensile rate 50mm / min, test temperature 25℃.

[0080] Thermal performance test: using differential scanning calorimeter, the test range is -50~300℃, the heating rate is 10℃min -1 .

[0081] Degradation performance test:

[0082] 1: Place the sample in distilled water, take samples every 14 days, wash and dry until constant weight is reached, and weigh.

[0083] 2: Place the specimens in seawater for natural degradation, take samples every 2 months, wash and dry until constant weight is reached.

[0084] 3: Place the specimens in nutrient soil and test them in a 25°C aging box. Take samples and weigh them every 14 days.

[0085] Table 1 Performance test results

[0086]

[0087]

[0088] From the data in Table 1, it can be seen that the PBS-based supramolecular degradable plastic has higher tensile strength and Young's modulus than ordinary PBS polyester, and has a higher glass transition temperature and thermal decomposition temperature, and can be used for high-temperature equipment and packaging materials. At the same time, it is controlled by imine and has good degradation ability in ordinary water bodies, seawater and soil. It can be degraded and recycled in natural areas, which is beneficial to the environment and sustainable development.

[0089] The above is a schematic description of the present invention and its implementation methods, which is not restrictive and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and, without departing from the purpose of the invention, designs a structure and an implementation method similar to the technical solution without creativity, they shall all fall within the protection scope of the present invention.

Claims

1. A PBS-based supramolecular degradable plastic, characterized in that The structural formula of a PBS-based supramolecular degradable plastic is: The value range of n is 10≤n≤100.

2. The method for preparing a PBS-based supramolecular degradable plastic according to claim 1, characterized in that The preparation method is specifically completed according to the following steps:

1. Preparation of low molecular weight PBS oligomers by melt polycondensation: Firstly, succinic acid, butanediol and tetrabutyl titanate are added into a three-necked flask, reacted at 160°C to 190°C for a period of time, then vacuumed to 10Pa to 100Pa, then heated to 220°C to 230°C for a period of time, and finally cooled to room temperature to obtain a low molecular weight PBS oligomer; 2. Preparation of PBS-CHO by terminal aldehyde modification of PBS oligomers: A low molecular weight PBS oligomer, 4-formylbenzoic acid, 4-dimethylaminopyridine and dicyclohexylcarbodiimide are added to chloroform, and the mixture is condensed and refluxed at 40°C to 60°C for a period of time. After the reaction is completed, the mixture is cooled to room temperature, filtered to remove solids, and the filtrate is concentrated and dripped into methanol at 0°C to 4°C dropwise, and the solids are filtered out. The solids are then washed with methanol and ether at 0°C to 4°C for 3 to 5 times respectively, and finally dried in vacuum to obtain PBS-CHO; 3. Oxidation of starch to S-CHO: Dispersing starch in deionized water to form a suspension, adding sodium periodate at 20°C to 50°C, adjusting the pH value to 2 to 4, reacting for a period of time at 20°C to 50°C in the dark, centrifuging, and collecting solid products; washing the collected solid products, freeze-drying, and obtaining S-CHO; 4. Preparation of PBS-based supramolecular degradable plastics: PBS-CHO and S-CHO are added to chloroform, and stirred and dissolved at 40°C to 60°C to obtain a mixed solution; amine is added to the mixed solution, and reacted for a period of time under magnetic stirring to obtain a gel product; The gel product is washed, placed in a fume hood to volatilize the solvent, and then vacuum dried to obtain a PBS-based supramolecular plastic prepolymer; the PBS-based supramolecular plastic prepolymer is pressed into a film, and then placed in an oven at 90°C to 110°C for curing for a period of time to obtain a PBS-based supramolecular degradable plastic.

3. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The mass ratio of succinic acid, butanediol and tetrabutyl titanate described in step 1 is (20g-100g):(17g-135g):(0.08g-0.4g).

4. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The reaction time at 160°C to 190°C in step 1 is 3h to 6h; the heating rate in step 1 is 5°C h -1 ~10℃h -1 ; The reaction time in step 1 at 220°C to 230°C is 10min to 120min.

5. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The mass volume ratio of the low molecular weight PBS polymer, 4-formylbenzoic acid, 4-dimethylaminopyridine, dicyclohexylcarbodiimide and chloroform described in step 2 is (2g~50g):(0.5g~3g):(0.05g~1g):(0.5g~5g):(60mL~100mL).

6. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The time of the condensation reflux reaction at 40°C to 60°C in step 2 is 24h to 48h; the temperature of the vacuum drying in step 2 is 50°C to 80°C, and the time of the vacuum drying is 10h to 14h.

7. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The volume ratio of starch, sodium periodate and deionized water described in step 3 is (3g-5g):(3g-10g):(50mL-100mL).

8. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that In step 3, the pH value is adjusted to 2 to 4 using dilute sulfuric acid with a mass fraction of 0.01 mol / L to 0.1 mol / L; in step 3, the reaction time is 0.5 h to 12 h under the conditions of 20° C. to 50° C. and protected from light; in step 3, the collected solid product is washed 3 to 5 times using deionized water, and then freeze-dried at -10° C. to -20° C. for 12 h to 24 h.

9. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The amine described in step 4 is one or more of diethylenetriamine, hexamethylenediamine, octanediamine, decanediamine, 4,4-methylenebiscyclohexylamine and tris(2-aminoethyl)amine; the molar volume ratio of PBS-CHO, S-CHO and chloroform described in step 4 is (1mmol-10mmol):(1mmol-5mmol):100mL; the molar ratio of the aldehyde group in PBS-CHO and S-CHO to the amino group in the amine described in step 4 is 1:

1.

10. The method for preparing a PBS-based supramolecular degradable plastic according to claim 2, characterized in that The magnetic stirring reaction time in step 4 is 8 hours to 12 hours; in step 4, the gel product is washed 3 to 5 times with anhydrous ethanol or methanol and placed in a fume hood to volatilize the solvent, and then vacuum dried at 50° C. to 70° C. for 12 hours to 24 hours to obtain a PBS-based supramolecular plastic prepolymer; in step 4, the PBS-based supramolecular plastic prepolymer is pressed at 80° C. to 100° C. and 10MPa to 30MPa for 5 minutes to 60 minutes to form a film; in step 4, the prepolymer is placed in an oven at 90° C. to 110° C. for curing for 12 hours to 24 hours.

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