阅读说明：本技术 聚乙烯醇基可降解塑料、其制备方法和应用、其回收方法 (Polyvinyl alcohol-based degradable plastic, preparation method and application thereof, and recovery method thereof ) 是由 孙俊奇 房旭 李懿轩 于 2019-08-27 设计创作，主要内容包括：本发明公开了一种聚乙烯醇基可降解塑料、其制备方法和应用、其回收方法。所述制备方法包括如下步骤：PVA溶液在酸性条件和改性剂作用下进行化学接枝反应即可；所述改性剂的结构式中具有一个苯基、一个醛基和至少一个可与PVA形成氢键作用的基团,所述醛基、所述可与PVA形成氢键作用的基团分别取代所述苯基上不同碳原子上的氢；所述改性剂占PVA的重复结构单元(即-C_2H_4O-)的摩尔百分比为15％～60％。本发明提供的聚乙烯醇基可降解塑料具有透明度高,力学强度高且不受环境湿度影响,非常容易降解,热稳定性好,生物相容性好,且具有可回收性、价格低、易规模化制备等优点。(The invention discloses a polyvinyl alcohol-based degradable plastic, a preparation method and application thereof, and a recovery method thereof. The preparation method comprises the following steps: carrying out chemical grafting reaction on the PVA solution under the acidic condition and the action of a modifier; the structural formula of the modifier is provided with a phenyl group, an aldehyde group and at least one group capable of forming hydrogen bond with PVA, and the aldehyde group and the group capable of forming hydrogen bond with PVA respectively replace hydrogen on different carbon atoms on the phenyl group; the modifier occupies the repeating structural unit of PVA (i.e., -C) 2 H 4 O‑) The mole percentage of the component (a) is 15 to 60 percent. The polyvinyl alcohol-based degradable plastic provided by the invention has the advantages of high transparency, high mechanical strength, no influence of environmental humidity, high easiness in degradation, high thermal stability, high biocompatibility, recoverability, low price, easiness in large-scale preparation and the like.)

1. The preparation method of the polyvinyl alcohol-based degradable plastic is characterized by comprising the following steps: carrying out chemical grafting reaction on the PVA solution under the acidic condition and the action of a modifier; the structural formula of the modifier is provided with a phenyl group, an aldehyde group and at least one group capable of forming hydrogen bond with PVA, and the aldehyde group and the group capable of forming hydrogen bond with PVA respectively replace hydrogen on different carbon atoms on the phenyl group; the modifier accounts for 15 to 60 percent of the mol percentage of the repeated structural unit of the PVA.

2. The method of claim 1, wherein the modifier has a molecular weight of 106-;

and/or the aldehyde group and the group capable of forming hydrogen bond with PVA adopt meta-position or para-position to replace hydrogen on different carbon atoms on the phenyl;

and/or the group capable of forming hydrogen bond interaction with PVA is one or more of hydroxyl, methoxy, ethoxy, fluoro, carboxyl, dimethylamino, methoxycarbonyl and methyl;

preferably, the modifier is selected from one or more of p-hydroxybenzaldehyde, 3, 4-dihydroxybenzaldehyde, vanillin, ethyl vanillin, 4-fluorobenzaldehyde, p-aldehyde benzoic acid, m-aldehyde benzoic acid, 4-dimethylaminobenzaldehyde, methyl p-formylbenzoate and p-methylbenzaldehyde;

more preferably, the modifier is p-aldehyde benzoic acid, or methyl p-formylbenzoate, or m-aldehyde benzoic acid, or a combination of p-methyl benzaldehyde and ethyl vanillin;

when the modifier is a combination of p-tolualdehyde and ethyl vanillin, the molar ratio of p-tolualdehyde and ethyl vanillin is preferably from 1:1 to 1: 3.

3. The method of claim 1, wherein the modifier comprises 20 to 40 mole percent of the repeating structural units of PVA.

4. The method according to claim 1, wherein the PVA solution is a solution obtained by dissolving PVA in a soluble solvent; wherein:

the PVA in the PVA solution is preferably 6 to 11 percent by mass;

the molecular weight of PVA is preferably 40000-140000, more preferably 70000;

the soluble solvent is preferably dimethyl sulfoxide or a mixed solvent formed by dimethyl sulfoxide and water;

when the soluble solvent is the mixed solvent, the volume ratio of dimethyl sulfoxide to water in the mixed solvent is preferably 3: 1-5: 1;

the dissolution is preferably carried out at 70 to 90 ℃, more preferably at 70 ℃.

5. The method according to claim 1, wherein the acidic condition is a strongly acidic condition, preferably an acidic condition having a pH of 3 or less, more preferably an acidic condition having a pH of 1;

and/or, the acidic condition is achieved by using a pH adjusting agent, preferably hydrochloric acid;

and/or the temperature of the chemical grafting reaction is 70-90 ℃, preferably 70 ℃;

and/or the time of the chemical grafting reaction is 1-3 h, preferably 2 h.

6. The method according to claim 1, wherein the chemical grafting reaction is followed by a post-treatment;

the post-treatment preferably comprises coating film drying or melt blow molding film forming of the reaction liquid; wherein:

the temperature for drying the coating film is preferably 60-120 ℃, and the time is preferably 10-30 min;

and/or the temperature of the melt blow molding film is preferably 160-190 ℃.

7. The polyvinyl alcohol-based degradable plastic prepared by the preparation method of any one of claims 1-6.

8. Use of the polyvinyl alcohol based degradable plastic as claimed in claim 7.

9. A method for recycling the polyvinyl alcohol based degradable plastic as claimed in claim 7, which comprises the following steps: the polyvinyl alcohol-based degradable plastic is completely dissolved in a soluble solvent.

10. The recovery method according to claim 9, wherein the soluble solvent is dimethyl sulfoxide or a mixed solvent of dimethyl sulfoxide and water; when the soluble solvent is the mixed solvent, the volume ratio of dimethyl sulfoxide to water in the mixed solvent is preferably 3: 1-5: 1;

and/or, the dissolving is carried out at room temperature;

and/or after complete dissolution, carrying out post-treatment; the post-treatment preferably comprises coating film drying or melt blow molding film forming of the reaction liquid; the temperature for drying the coating film is preferably 60-120 ℃, and the time is preferably 10-30 min; and/or the temperature of the melt blow molding film is preferably 160-190 ℃.

Technical Field

The invention relates to a polyvinyl alcohol-based degradable plastic, a preparation method and application thereof, and a recovery method thereof.

Background

Since the advent of plastics, while bringing convenience to human life, white pollution caused by plastics has become a primary problem which plagues the global environment. Today, plastic waste is produced in 2.75 million tons per year worldwide, and this value is expected to exceed 5 million tons by 2050. Most of the plastics are high in recycling cost and difficult to degrade in a short time, only less than 10% of the plastics are recycled, and the accumulated plastics are accumulated, so that more and more plastic wastes bring great pressure to the environment ecology. Although several classes of plastics with degradation properties have been developed, they still have many problems in practical applications. Taking a common polylactic acid (PLA) degradable plastic as an example, the degradation of the PLA needs to be decomposed by microorganisms after hydrolysis reaction, and the hydrolysis of the PLA needs to meet two basic conditions: 50% -60% humidity and 50-70 deg.C. Only under these conditions is the degradation achieved relatively quickly. In natural environment, if the conditions of high temperature and humidity are not satisfied, the degradation speed of PLA is very slow. Light, heat, etc. in the natural environment can decompose the photodegradable plastic into small molecules, but the photodegradable plastic cannot be degraded in the case where light is not visible, such as buried in soil.

The water-soluble polyvinyl alcohol (PVA) is the only vinyl polymer which can be used as a carbon source and an energy source by bacteria, belongs to a biodegradable high molecular material and has good biocompatibility. It can be produced in large scale by non-petroleum route, and has low cost and unique advantages in food and medicine packaging. Although the water-soluble PVA film has excellent mechanical property and degradable function, the application field of the material is greatly limited by the characteristic that the material is dissolved immediately when meeting water. At present, the mechanical strength of PVA-based plastics is greatly reduced in humid environments, so that it cannot be used.

In the prior art, glutaraldehyde and formaldehyde are used for chemically crosslinking PVA, so that the strength and water resistance of the PVA can be effectively improved, but the water resistance of the PVA material prepared by the method still needs to be improved, in addition, the stretchability of the PVA material is greatly reduced, and the PVA material is difficult to completely degrade under mild natural conditions.

Disclosure of Invention

The invention aims to solve the technical problem that the mechanical strength of PVA-based plastics in the prior art is greatly reduced in a humid environment so as to be incapable of being used; the existing modification method has the defect of poor degradation performance, and provides the polyvinyl alcohol-based degradable plastic, the preparation method and the application thereof, and the recovery method thereof. The polyvinyl alcohol-based degradable plastic provided by the invention has the advantages of high transparency, high mechanical strength, no influence of environmental humidity, high easiness in degradation, high thermal stability, high biocompatibility, recoverability, low price, easiness in large-scale preparation and the like.

The invention provides a preparation method of polyvinyl alcohol-based degradable plastic, which comprises the following steps: carrying out chemical grafting reaction on the PVA solution under the acidic condition and the action of a modifier; the structural formula of the modifier is provided with a phenyl group, an aldehyde group and at least one group capable of forming hydrogen bond with PVA, and the aldehyde group and the group capable of forming hydrogen bond with PVA respectively replace hydrogen on different carbon atoms on the phenyl group; the modifier occupies the repeating structural unit of PVA (i.e., -C)₂H₄The mol percentage of O-) is 15 percent to 60 percent.

In the present invention, the molecular weight of the modifier is preferably 106-300.

In the structural formula of the modifier, when the aldehyde group and the group capable of forming a hydrogen bond with PVA are used for respectively substituting hydrogen on different carbon atoms on the phenyl, any substitution mode can be adopted, namely, ortho-position substitution, meta-position substitution or para-position substitution can be adopted, and preferably meta-position substitution or para-position substitution is adopted.

In the present invention, the group capable of forming a hydrogen bond with PVA has a conventional meaning in the art, and preferably one or more of hydroxyl group, methoxy group, ethoxy group, fluoro group, carboxyl group, dimethylamino group, methoxycarbonyl group and methyl group. More preferably, the modifier is selected from one or more of p-hydroxybenzaldehyde, 3, 4-dihydroxybenzaldehyde, vanillin, ethyl vanillin, 4-fluorobenzaldehyde, p-aldehyde benzoic acid, m-aldehyde benzoic acid, 4-dimethylaminobenzaldehyde, methyl p-formylbenzoate and p-methylbenzaldehyde, and further more preferably is p-aldehyde benzoic acid, or methyl p-formylbenzoate, or m-aldehyde benzoic acid, or a combination of p-methylbenzaldehyde and ethyl vanillin.

The mechanism of the invention is as follows: the super-molecular acting force in the polyvinyl alcohol-based degradable plastic obtained by the invention is derived from the hydrophobic action of the whole hydrophobic group, and is derived from the hydrogen bond action of the special group on the phenyl and the PVA, and the hydrophobic action and the hydrogen bond action are mutually cooperated.

In the present invention, the modifier occupies the repeating structural unit (i.e., -C) of PVA₂H₄The molar percentage of O-) is understood as meaning the grafting yield or the grafting molar ratio. In the preferred embodiments of the present application, the mole percentages of the modifier in the repeating structural units of PVA are 15%, 20%, 30%, 40%, 50% and 60%, respectively. Preferably, the modifier accounts for 20 to 40 mole percent of the repeating structural unit of the PVA.

In a preferred embodiment of the present application, p-aldehyde benzoic acid is used as a modifier, and the modifier accounts for preferably 20 to 40 mol% of the repeating structural unit of PVA. The reaction formula of the chemical grafting reaction is shown as the following formula:

in a preferred embodiment of the present application, methyl p-formylbenzoate is used as the modifier, and the modifier preferably accounts for 20 to 40 mol% of the repeating structural unit of PVA. The reaction formula of the chemical grafting reaction is shown as the following formula:

in another preferred embodiment of the present application, the modifier used is m-aldehyde benzoic acid, said modifier preferably accounting for 20 to 40% of the molar percentage of the recurring structural units of PVA.

In another preferred embodiment of the present application, a mixture of p-tolualdehyde and ethyl vanillin is used as the modifier, wherein the molar ratio of p-tolualdehyde and ethyl vanillin is preferably 1:1 to 1: 3. The reaction formula of the chemical grafting reaction is shown as the following formula:

in the present invention, the PVA solution has a meaning conventional in the art, and means a solution obtained by dissolving PVA in a soluble solvent. The PVA solution preferably contains 6 to 11 mass percent of PVA.

In the invention, PVA is a conventional raw material in the field, and the molecular weight of PVA is preferably 40000-140000. In a preferred embodiment of the present application, PVA is available from aladdin having a molecular weight of 70000.

Wherein the soluble solvent is a solvent capable of dissolving PVA, such as dimethyl sulfoxide (DMSO) or a mixed solvent of dimethyl sulfoxide (DMSO) and water, which is conventional in the art. In the mixed solvent, the volume ratio of DMSO to water in the mixed solvent is preferably 3: 1-5: 1.

Wherein the dissolution is preferably carried out at 70-90 ℃, more preferably at 70 ℃.

In the present invention, the acidic condition is preferably a strongly acidic condition, more preferably an acidic condition having a pH of 3 or less. For example, in a preferred embodiment of the present application, acidic conditions refer to pH 1; the acidic condition is achieved by using a pH regulator, which is hydrochloric acid.

In the present invention, the chemical grafting reaction conditions may be those conventional in the art for chemically crosslinking PVA. The temperature of the chemical grafting reaction is preferably 70 to 90 ℃, more preferably 70 ℃. The time of the chemical grafting reaction is preferably 1 to 3 hours, and more preferably 2 hours.

In the present invention, after the chemical grafting reaction, a post-treatment is preferably performed, and the post-treatment preferably includes performing film drying or melt blow molding on the reaction solution to form a film. The conditions for drying the coating film are conventional in the field, the temperature is preferably 60-120 ℃, and the drying time is preferably 10-30 min. The conditions for melt blown film formation are conventional in the art, and the temperature is preferably 160-190 ℃.

In a preferred embodiment of the present application, the preparation method of the polyvinyl alcohol-based degradable plastic comprises: dissolving PVA in an organic solvent DMSO or a mixed solvent of DMSO and water at 90 ℃ to obtain a PVA solution, wherein the mass fraction of the PVA in the PVA solution is 6-11%, heating the solution to 70-90 ℃, adjusting the pH of the solution to 1, adding one or two of modifiers into the solution, grafting the modifier with the molar percentage of 20-40%, and reacting for two hours to obtain the PVA solution modified with a supramolecular acting force group; then the solution is coated and dried to obtain the polyvinyl alcohol based degradable plastic.

The invention also provides the polyvinyl alcohol-based degradable plastic prepared by the preparation method.

The invention introduces a group with supramolecular acting force on a PVA chain through simple one-step chemical modification at room temperature, and prepares the PVA-based degradable plastic which has high strength and can be degraded in soil and seawater based on the cooperation of the modification group and the multiple supramolecular acting force of the PVA chain.

The invention also provides application of the polyvinyl alcohol-based degradable plastic.

The polyvinyl alcohol-based degradable plastic prepared by the invention can replace plastic products used in daily life, such as handbag and packaging bag. The plastic may be in the form of a plastic film or a plastic film.

Compared with the traditional PVA plastic film, the polyvinyl alcohol-based degradable plastic has improved mechanical properties, and most importantly, the application range of the PVA material is greatly expanded, for example, the PVA film has good performance and can be degraded, and can be made into various plastic products, but can be dissolved when meeting water and cannot be used in a humid environment. It cannot replace the existing non-degradable non-environment-friendly plastic products. However, the polyvinyl alcohol-based degradable plastic not only has good mechanical properties, but also has high stability and degradability.

The invention also provides a method for recovering the polyvinyl alcohol-based degradable plastic, which comprises the following steps: completely dissolving the polyvinyl alcohol-based degradable plastic in a soluble solvent.

Wherein the soluble solvent is a solvent capable of dissolving PVA, such as dimethyl sulfoxide (DMSO) or a mixed solvent of dimethyl sulfoxide (DMSO) and water, which is conventional in the art. In the mixed solvent, the volume ratio of DMSO to water in the mixed solvent is preferably 3: 1-5: 1.

Wherein the dissolution is carried out under conditions conventional in the art, such as room temperature (typically 5-40 ℃).

In the present invention, after the complete dissolution, preferably, a post-treatment is further performed; the post-treatment is preferably drying of a coating film or melt blow molding of a film from a solution obtained by complete dissolution. The conditions for drying the coating film are conventional in the field, the temperature is preferably 60-120 ℃, and the drying time is preferably 10-30 min. The conditions for melt blown film formation are conventional in the art, and the temperature is preferably 160-190 ℃.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The reagents and starting materials used in the present invention are commercially available.

The positive progress effects of the invention are as follows:

the polyvinyl alcohol-based degradable plastic with good flexibility prepared by the invention has the breaking strength of 47MPa and the transmittance in a visible light region of not less than 98 percent, can be completely degraded in alkaline water, seawater and soil, can maintain high mechanical strength in fresh water, and meets the use performance of the PVA-based degradable plastic in a high-humidity environment.

Drawings

FIG. 1(a) is an infrared spectrum of the polyvinyl alcohol based degradable plastic of example 1.

FIG. 1(b) is a graph showing the result of measuring the transmittance in the visible light region of the polyvinyl alcohol-based degradable plastic of example 1.

FIG. 2 shows the results of mechanical property measurements of the polyvinyl alcohol-based degradable plastic of example 1.

FIG. 3 is the result of testing the mechanical properties of the polyvinyl alcohol-based degradable plastic of example 1 after saturation with water.

FIG. 4 is a comparison of thermal stability of the polyvinyl alcohol based degradable plastic of example 1 and a PVA film.

Fig. 5 shows the result of the biocompatibility test of the polyvinyl alcohol-based degradable plastic of example 1.

FIG. 6 shows the result of measuring the mechanical properties (grafting ratio: 15%) of the polyvinyl alcohol-based degradable plastic of example 2 after saturation with water.

FIG. 7 shows the result of measuring the mechanical properties (grafting ratio: 30%) of the polyvinyl alcohol-based degradable plastic of example 3 after saturation with water.

FIG. 8 shows the result of measuring the mechanical properties (grafting ratio: 40%) of the polyvinyl alcohol-based degradable plastic of example 4 after saturation with water.

FIG. 9 shows the result of measuring the mechanical properties (grafting ratio 50%) of the polyvinyl alcohol-based degradable plastic of example 5 after saturation with water.

FIG. 10 shows the results of measuring the mechanical properties of the polyvinyl alcohol-based degradable plastic of example 6 after saturation with water (60% grafting ratio).

FIG. 11 shows the result of measuring the mechanical properties (grafting ratio: 10%) of the polyvinyl alcohol-based degradable plastic of comparative example 1 after saturation with water.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

Of the starting materials in the following examples, PVA powder was obtained from aladdin and had a molecular weight of 70000.

Example 1

In example 1, the preparation method of the polyvinyl alcohol-based degradable plastic comprises the following steps: dissolving PVA in an organic solvent DMSO at 90 ℃ with the mass fraction of 6%, heating the solution to 70 ℃, adjusting the pH of the solution to 1 by using hydrochloric acid, adding a modifier p-aldehyde benzoic acid into the solution, grafting the p-aldehyde benzoic acid with the molar percentage of 20%, and reacting for two hours to obtain a PVA solution modified with a supramolecular acting force group; the solution was then subjected to film coating drying (drying conditions: 80 ℃ C., 20min) to obtain a polyvinyl alcohol-based degradable plastic (hereinafter also referred to as "PVA-based supramolecular plastic") film having a thickness of 30 μm.

Effect example 1

The embodiment of the effect mainly aims at the performance detection of the polyvinyl alcohol based degradable plastic film prepared in the embodiment 1. The method comprises the following steps:

infrared detection:

the degradable plastic obtained in example 1 and having a thickness of 30 μm was subjected to infrared examination, as shown in FIG. 1(a), and the results showed that the PVA-based degradable plastic was 1017cm^-1The new infrared peak appearing at the wavelength is the infrared characteristic peak of acetal (which is the product obtained by condensing one molecule of aldehyde and two molecules of alcohol), which proves the successful proceeding of the acetal reaction, thereby reflecting the success of the grafting reaction.

In FIG. 1(a), a sample of "supramolecular acting group" represents p-aldehyde benzoic acid as a modifier used in example 1, and a sample of "PVA" represents a PVA film having a thickness of 30 μm, which is prepared by dissolving a commercially available PVA powder and then drying the solution to form a film, and the drying film-forming process is the same as that of example 1.

And (3) detecting the light transmittance:

the light transmittance of the degradable plastic obtained in example 1 was measured, and as shown in FIG. 1(b), it was confirmed that the transmittance of more than 98% was maintained in the visible light region.

And (3) mechanical property detection:

the mechanical property of the degradable plastic with the thickness of 30 microns obtained in example 1 is also tested, and meanwhile, the polyethylene plastic bag with the thickness of 30 microns and used in daily life and the polyethylene sealing bag with the thickness of 30 microns are compared, as shown in fig. 2, the result shows that the tensile strength of the degradable PVA-based supramolecular plastic is about 47MPa, the modulus is up to 400MPa (calculated according to the slope of the curve in the figure), and the strength of the degradable plastic is greatly improved compared with the polyethylene plastic bag (the tensile strength is about 21MPa) and the sealing bag (the tensile strength is about 23MPa) used in daily life.

Load detection:

the method for detecting the load-carrying capacity of the degradable plastic with the thickness of 30 microns and obtained in the example 1 comprises the following steps: the weight of 2kg weight was lifted from the bottom using plastic, and the result showed that the degradable plastic was intact.

And (3) detecting the mechanical property after water absorption saturation:

FIG. 3 shows that the degradable PVA-based supramolecular plastic prepared in example 1 has excellent stability in fresh water, has a water content of only 9 wt% after saturation with water, and has a tensile strength of about 26MPa, which is still higher than that of a polyethylene plastic bag in daily use (about 21MPa), and the commercialized PVA film is soluble in water after meeting water. The degradable PVA-based supramolecular plastic disclosed by the invention still has better performance than a commercial PVA film after being saturated with water.

And (3) testing the degradation performance:

the polyvinyl alcohol-based degradable plastic obtained in example 1 was subjected to a degradation performance test, and the results show that:

the polyvinyl alcohol-based degradable plastic with the thickness of 30 micrometers is completely dissolved in an alkaline aqueous solution (a sodium hydroxide solution with the pH value of 12) at room temperature for 1 minute.

The polyvinyl alcohol based degradable plastic with a thickness of 30 microns was cut into small pieces of uniform size, about 2cm by 3cm by 30 microns, weighed separately and buried in soil. The mass is reduced by 12% after two days, 29% after one week, 76% after two weeks, and the fertilizer is completely degraded in soil after 20 days.

The polyvinyl alcohol-based degradable plastic with the thickness of 30 microns is changed into a sol state within three days in seawater, and can be completely degraded within ten days.

The degradable PVA-based supramolecular plastic can be completely degraded in the alkaline aqueous solution at room temperature, and even the supramolecular plastic can be completely degraded in soil and seawater.

And (3) detecting thermal stability:

FIG. 4 is a comparison of thermal stability of the polyvinyl alcohol based degradable plastic of example 1 and a PVA film. The PVA film is prepared by dissolving commercially available PVA powder and then drying to form a film, the drying film forming process is the same as that of the embodiment 1, and the thicknesses of two film samples for detection are both 30 micrometers.

As can be seen from FIG. 4, PVA starts to decompose at 226 ℃, supramolecular plastic starts to decompose at about 265 ℃, and the decomposition temperature is increased by 39 ℃; the stability of the supramolecular plastic is particularly good below 100 ℃. FIG. 4 shows that the degradable PVA-based supramolecular plastic has better thermal stability than PVA film.

And (3) detecting biocompatibility:

the supramolecular plastic with the thickness of 30 microns prepared in example 1 is cut into small blocks with certain mass, the small blocks are respectively soaked in a certain volume of cell culture solution for 5 days to obtain cell culture solutions with different concentrations (specific concentration setting conditions are developed according to the standard of figure 5, a control group with the corresponding concentration of 0mg/ml and experimental groups with the concentrations of 0.5,1 and 2mg/ml respectively), then the cell culture solutions are respectively used for culturing human normal hepatocytes (LO2 cells) and mouse fibroblasts (L929 cells), and after 72 hours of culture, the activity of the cells is observed and counted, so that the cytotoxicity of the supramolecular plastic is reflected.

The results are shown in fig. 5, and show that human normal hepatocytes and mouse fibroblasts all maintain high survival rates of 95% or more in the culture solution containing no supramolecular plastic (corresponding to the control group with a concentration of 0 mg/ml) and the culture solution containing supramolecular plastic (corresponding to the experimental groups with concentrations of 0.5,1, and 2 mg/ml), and the results prove that supramolecular plastic has no cytotoxicity basically.

Detecting the recoverability:

the method comprises the following specific steps: after the polyvinyl alcohol-based degradable plastic with the thickness of 30 micrometers prepared in example 1 is further cut into pieces, the pieces are dissolved in DMSO at room temperature, and then the drying film-forming process operation is carried out again according to example 1, so that a recovered product is obtained. The detection proves that the performance of the recycled product is completely the same as that of the raw material before recycling (the polyvinyl alcohol-based degradable plastic prepared in example 1).

The degradable supramolecular material prepared based on the supramolecular effect has a higher degradation speed and milder degradation conditions due to the weak interaction force of the internal action force compared with the degradable material based on the covalent bond, and has high-speed and high-efficiency fracture-recombination performance, so that the degradable supramolecular material has recyclability.

Examples 2 to 6

The results of the tests were examined, with the preparation of the starting materials, the process steps and the conditions being identical to those of example 1, for the degree of grafting (15%, 30%, 40%, 50%, 60%, respectively) as the only variable. The water saturation ratio and the strength data after water saturation of the PVA-based supramolecular plastic prepared in each example are shown in table 1 below and fig. 6 to 10.

TABLE 1 comparison of the Properties of examples 1-6 with comparative example 1

It should be noted that, although the tensile strength corresponding to the 15% grafting ratio of example 2 does not reach the tensile strength (about 21MPa) of the polyethylene plastic bag used in daily life, the strength can also meet the basic use requirement, and the defect that the polyethylene plastic bag cannot be degraded is perfectly overcome.

When the grafting ratio is 50%, the water content of the obtained PVA-based supramolecular plastic after water absorption saturation is only 2%, and as shown by tensile data, the tensile strength of the material after water absorption saturation is 42MPa (the result is shown in FIG. 9). It can be seen that the increased grafting yield, although it is possible to further improve the stability of the material in water, means that more raw material is consumed and that PVA-based supramolecular plastics with a grafting yield of 50% have a certain yellow color.

When the graft ratio is 60%, the strength of the material after water saturation is further improved (the result is shown in FIG. 10), but the uneconomical property due to the consumption of raw materials is more serious than that in the case of 50% graft ratio.

In contrast, the supramolecular plastic with the grafting rate of 20-40% not only has higher mechanical strength and water resistance, but also has high transparency and relatively lower preparation cost.

In addition, the degradable plastics prepared in examples 2 to 6 and having a thickness of 30 μm were subjected to infrared detection, light transmittance detection, load detection, degradation property detection, thermal stability detection, biocompatibility detection and recyclability detection as shown in effect example 1, respectively, and the results show that the effects all reach a level equivalent to that of effect example 1.

Comparative example 1

The comparative results of the tests in which the grafting yield was the only variable were examined on the basis of the preparation of the starting materials, the process steps and the conditions which were identical to those of example 1.

When the grafting ratio is 10%, the water content of the obtained PVA-based supramolecular plastic after water saturation reaches 75%, and if tensile data show that the tensile strength of the material after water saturation is low and is only 2.7MPa (results are shown in FIG. 11 and shown in Table 1), that is, the PVA-based supramolecular plastic with the grafting ratio of 10% is very soft after water absorption, so that the daily use requirement cannot be completely met.

Example 7

The results of the tests were conducted while examining the kind of modifier (the modifier specifically used in this example was m-aldehyde benzoic acid) as the only variable, on the basis of the same preparation of the starting materials, process steps and conditions as in example 1.

The degradable plastic with the thickness of 30 micrometers prepared in the embodiment is respectively subjected to infrared detection, light transmittance detection, load detection, mechanical property detection after water saturation, degradation property detection, thermal stability detection, biocompatibility detection and recoverability detection shown in effect embodiment 1, and the results show that the effects can reach the level equivalent to that of effect embodiment 1.

Example 8

The results of the experiments conducted on the preparation of the starting materials, the process steps and the conditions as in example 1 were examined for the type of modifier (a mixture of tolualdehyde and ethyl vanillin in which the molar ratio of tolualdehyde to ethyl vanillin was 1:1 was specifically used in this example) as the only variable.

The degradable plastic with the thickness of 30 micrometers prepared in the embodiment is respectively subjected to infrared detection, light transmittance detection, load detection, mechanical property detection after water saturation, degradation property detection, thermal stability detection, biocompatibility detection and recoverability detection shown in effect embodiment 1, and the results show that the effects can reach the level equivalent to that of effect embodiment 1.

Example 9

The results of the tests were conducted while examining the kind of the modifier (methyl p-formylbenzoate is specifically used as the modifier in this example) as the only variable, on the basis of the same preparation of the starting materials, the same process steps and the same conditions as in example 1.

The degradable plastic with the thickness of 30 micrometers prepared in the embodiment is respectively subjected to infrared detection, light transmittance detection, load detection, mechanical property detection after water saturation, degradation property detection, thermal stability detection, biocompatibility detection and recoverability detection shown in effect embodiment 1, and the results show that the effects can reach the level equivalent to that of effect embodiment 1.