阅读说明：本技术 一种双动态交联的pH响应型聚乙烯醇水凝胶及其制法 (Double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel and preparation method thereof ) 是由 林文龙 于 2020-05-12 设计创作，主要内容包括：本发明涉及水凝胶材料技术领域,且公开了一种双动态交联的pH响应型聚乙烯醇水凝胶,包括以下配方原料及组分：端酰肼基聚二醇、偶联剂、交联剂、羧甲基壳聚糖、聚乙烯醇。该一种双动态交联的pH响应型聚乙烯醇水凝胶,端酰肼基聚乙二醇中酰肼基与戊二醛反应形成酰腙键,在与羧甲基壳聚糖进行偶联反应,羧甲基壳聚糖再与聚乙烯醇通过硼酸形成三维网络水凝胶,将化学动态共价键酰腙键和硼酸酯键引入水凝胶的基体中,发生拉伸和压缩等形变,酰肼基和硼酸酯键会重新键合,恢复交联网络,呈现出良好的自愈性,并且酰肼基具有pH敏感性,在酸性条件下会发生化学键的断裂,在中性条件下酰肼基会重新键合,赋予了水凝胶材料良好的pH相应性。(The invention relates to the technical field of hydrogel materials, and discloses a double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel which comprises the following formula raw materials and components: the preparation method comprises the following steps of hydrazide-terminated polyglycol, a coupling agent, a crosslinking agent, carboxymethyl chitosan and polyvinyl alcohol. According to the double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel, hydrazide groups in terminal hydrazide-based polyethylene glycol react with glutaraldehyde to form hydrazone bonds, coupling reaction is carried out on the hydrazone bonds and carboxymethyl chitosan, the carboxymethyl chitosan and polyvinyl alcohol form three-dimensional network hydrogel through boric acid, the hydrazone bonds and the boric acid ester bonds with chemical dynamic covalent bonds are introduced into a matrix of the hydrogel, deformation such as stretching and compression occurs, the hydrazide groups and the boric acid ester bonds can be re-bonded, a cross-linked network is recovered, good self-healing performance is presented, the hydrazide groups have pH sensitivity, chemical bond breakage can occur under an acidic condition, the hydrazide groups can be re-bonded under a neutral condition, and good pH responsiveness is endowed to a hydrogel material.)

1. A double dynamic cross-linked pH response type polyvinyl alcohol hydrogel comprises the following raw materials and components, and is characterized in that: the mass ratio of the hydrazide-terminated polyglycol to the coupling agent to the cross-linking agent to the carboxymethyl chitosan to the polyvinyl alcohol is 6-15:0.5-2:0.5-1.2:50-80: 100.

2. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 1, wherein: the coupling agent is glutaraldehyde and the cross-linking agent is boric acid.

3. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 1, wherein: the preparation method of the hydrazide-terminated polyglycol comprises the following steps:

(1) adding polyethylene glycol 2000 and an accelerant 4-dimethylaminopyridine into an anhydrous ethyl acetate solvent, placing the mixture into a low-temperature reactor, slowly dropwise adding methanesulfonyl chloride at 0-5 ℃ in a nitrogen atmosphere, heating to 15-30 ℃, reacting for 60-80h, and performing extraction, washing, recrystallization and drying processes on the solution to prepare the end-sulfonyl polyethylene glycol;

(2) adding terminal sulfonyl ethylene glycol, methyl p-hydroxybenzoate and promoter potassium carbonate into an acetone solvent, heating to 60-80 ℃, reacting for 30-40h, cooling the solution to room temperature, extracting, washing, recrystallizing and drying to obtain terminal formate polyethylene glycol;

(3) adding aqueous solution of terminal formate polyethylene glycol and hydrazine hydrate into ethyl acetate solvent, heating to 75-90 ℃, reacting for 30-40h, cooling the solution to room temperature, extracting, washing, recrystallizing and drying to obtain the terminal hydrazide-based polyglycol.

4. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 3, wherein: the mass ratio of the polyethylene glycol to the 4-dimethylaminopyridine to the methanesulfonyl chloride is 1:0.15-0.25: 0.2-0.3.

5. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 3, wherein: the mass ratio of the sulfonyl-terminated glycol to the methyl p-hydroxybenzoate to the potassium carbonate is 1:4.2-5.5: 0.7-0.85.

6. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 3, wherein: the mass ratio of the formate-terminated polyethylene glycol to the hydrazine hydrate is 1: 1.8-2.5.

7. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 3, wherein: the low-temperature reaction instrument comprises a heat insulation layer, a liquid nitrogen chamber fixedly connected with the inside of the base, a reaction bottle is placed above the base, a condensing tube fixedly connected with the right side of the liquid nitrogen chamber, a condensing tube right-end fixedly connected with the condensing chamber, a switching valve fixedly connected with the inside of the condensing chamber, a temperature sensor fixedly connected with the lower side of the switching valve, a temperature sensor movably connected with an adjusting rod, an adjusting nut movably connected with the lower side of the adjusting rod, a temperature sensitive probe movably connected with the lower side of the adjusting nut, a cooling tube fixedly connected with the right side.

8. The dual dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel of claim 1, wherein: the preparation method of the double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel comprises the following steps:

(1) adding terminal hydrazide-based polyglycol, carboxymethyl chitosan and coupling agent glutaraldehyde into distilled water solvent, heating to 50-70 ℃, reacting for 6-10h, adding polyvinyl alcohol, stirring at constant speed for 20-40min, adding cross-linking agent boric acid, cooling to 25-40 ℃, reacting for 5-10h, standing for 15-25h, filtering and washing the solution, and preparing the double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel.

Technical Field

The invention relates to the technical field of hydrogel materials, in particular to a double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel and a preparation method thereof.

Background

The hydrogel is a three-dimensional network structure gel with strong hydrophilicity, can quickly absorb a large amount of water in water to carry out a swelling process, can keep a large amount of water in a swelling state without dissolving, the absorption capacity of the water is closely related to the degree of crosslinking, the lower the degree of crosslinking, the higher the water absorption capacity, the aggregation state of the hydrogel is neither complete solid nor complete liquid, the solid behavior of the hydrogel can maintain the shape and the volume under certain conditions, the liquid behavior of the hydrogel is that a solute can be diffused or permeated from the hydrogel, and the hydrogel material is used as a high water absorption and high water retention material and has wide application in aspects of cosmetic masks, cooling patches, agricultural films, mineral dust suppressants, medical drug carriers and the like.

Polyvinyl alcohol is a common hydrogel material, and can be subjected to freezing and melting treatment to obtain a stable hydrogel material, according to the response condition of the hydrogel to external stimuli, the hydrogel can be divided into traditional hydrogel and environment-sensitive hydrogel, the traditional hydrogel is insensitive to the change of environment such as temperature or pH, the environment-sensitive hydrogel can sense the tiny change or stimulus of external environment such as temperature, pH, light, electricity and the like, and can produce a kind of macromolecule gel with corresponding physical structure and chemical property changes and even mutation, however, the traditional polyvinyl alcohol hydrogel material has no pH response type, and the rigidity and the strength of the polyvinyl alcohol hydrogel are poor, the polyvinyl alcohol hydrogel material can crack and decompose under certain stretching and pressure, has no self-healing effect, and limits the practical application of the polyvinyl alcohol hydrogel material.

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel and a preparation method thereof, which solve the problem that the polyvinyl alcohol hydrogel does not have pH responsiveness and simultaneously solve the problems that the polyvinyl alcohol hydrogel has poor rigidity and strength and does not have self-healing property.

(II) technical scheme

In order to achieve the purpose, the invention provides the following technical scheme: a double dynamic cross-linked pH response type polyvinyl alcohol hydrogel comprises the following raw materials and components: the mass ratio of the hydrazide-terminated polyglycol to the coupling agent to the cross-linking agent to the carboxymethyl chitosan to the polyvinyl alcohol is 6-15:0.5-2:0.5-1.2:50-80: 100.

Preferably, the coupling agent is glutaraldehyde and the crosslinking agent is boric acid.

Preferably, the preparation method of the hydrazide-terminated polyglycol comprises the following steps:

(1) adding an anhydrous ethyl acetate solvent, polyethylene glycol 2000 and an accelerant 4-dimethylaminopyridine into a reaction bottle, slowly dropwise adding methanesulfonyl chloride into the reaction bottle in a low-temperature reactor at 0-5 ℃ in a nitrogen atmosphere, heating to 15-30 ℃, uniformly stirring for reaction for 60-80h, and performing extraction, washing, recrystallization and drying processes on the solution to prepare the sulfonyl-terminated polyethylene glycol.

(2) Adding an acetone solvent, terminal sulfonyl ethylene glycol and methyl p-hydroxybenzoate into a reaction bottle, stirring for dissolving, adding an accelerator potassium carbonate, putting into an oil bath pot, heating to 60-80 ℃, stirring at a constant speed for reaction for 30-40h, cooling the solution to room temperature, and performing extraction, washing, recrystallization and drying processes to prepare the terminal formate polyethylene glycol.

(3) Adding an ethyl acetate solvent and a terminal formate-based polyethylene glycol into a reaction bottle, stirring and dissolving, then adding a hydrazine hydrate aqueous solution, heating to 75-90 ℃, uniformly stirring and reacting for 30-40h, cooling the solution to room temperature, and performing extraction, washing, recrystallization and drying processes to obtain the terminal hydrazide-based polyglycol.

Preferably, the mass ratio of the polyethylene glycol to the 4-dimethylaminopyridine to the methanesulfonyl chloride is 1:0.15-0.25: 0.2-0.3.

Preferably, the mass ratio of the terminal sulfonyl glycol to the methyl p-hydroxybenzoate to the potassium carbonate is 1:4.2-5.5: 0.7-0.85.

Preferably, the mass ratio of the terminal formate-based polyethylene glycol to the hydrazine hydrate is 1: 1.8-2.5.

Preferably, the low temperature reaction appearance includes the insulating layer, the inside fixedly connected with liquid nitrogen room of insulating layer, the inside and base fixed connection of liquid nitrogen room, the reaction bottle has been placed to the base top, liquid nitrogen room right side below fixedly connected with condenser pipe, the condenser pipe right-hand member fixedly connected with condenser chamber, the inside fixedly connected with change-over valve of condenser chamber, change-over valve below fixedly connected with temperature sensing ware, temperature sensing ware swing joint has the regulation pole, adjust pole below swing joint has adjusting nut, adjusting nut below swing joint has the temperature sensitive probe, condenser chamber right side fixedly connected with cooling tube, the cooling tube right side and refrigerator fixed connection.

Preferably, the method for preparing the double-dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel comprises the following steps:

(1) adding a distilled water solvent, hydrazide-terminated polyglycol and carboxymethyl chitosan into a reaction bottle, stirring for dissolving, adding a coupling agent glutaraldehyde, heating to 50-70 ℃ in an oil bath pot, stirring at a constant speed for 6-10h, adding polyvinyl alcohol, stirring at a constant speed for 20-40min, adding a cross-linking agent boric acid, cooling to 25-40 ℃, stirring at a constant speed for 5-10h, standing for 15-25h, filtering and washing the solution, and preparing the double-dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel.

(III) advantageous technical effects

Compared with the prior art, the invention has the following beneficial technical effects:

according to the double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel, two terminal hydroxyls of polyethylene glycol react with methanesulfonyl chloride to obtain terminal sulfonyl polyethylene glycol, sulfonyl groups react with phenolic hydroxyls of methyl p-hydroxybenzoate to obtain terminal formate-based polyethylene glycol, formate groups react with hydrazine hydrate to obtain terminal hydrazide-based polyethylene glycol, amino groups in hydrazide groups form acylhydrazone bonds under the action of glutaraldehyde, the acylhydrazone bonds are subjected to coupling reaction with amino groups in carboxymethyl chitosan, and the carboxymethyl chitosan and polyvinyl alcohol form a dynamically cross-linked three-dimensional network hydrogel through boric acid.

In the double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel, the acylhydrazone bond and the borate bond are chemical dynamic covalent bonds, the acylhydrazone bond and the borate bond are introduced into a matrix of the polyvinyl alcohol hydrogel to form a double-dynamic network, so that the hydrogel material is endowed with obvious dynamic cross-linking balance, under the action of external force, the deformation such as stretching, compression and the like occurs, the hydrazide group and the boric acid ester bond can be quickly bonded again, the cross-linked network is recovered, the hydrogel material can be reversibly repaired, the self-healing performance is good, and the hydrazide group has pH sensitivity, can be broken under the acidic condition to change the polyvinyl alcohol hydrogel from a gel solid to a sol liquid, and the hydrazide group can be bonded again under the neutral condition, so that the polyvinyl alcohol hydrogel is changed from the sol liquid to the gel solid, and the hydrogel material has good pH response.

Drawings

FIG. 1 is a schematic front view of a low temperature reactor;

fig. 2 is an enlarged schematic view of the switch valve.

1. A thermal insulation layer; 2. a liquid nitrogen chamber; 3. a base; 4. a reaction bottle; 5. a condenser tube; 6. a condensing chamber; 7. a changeover valve; 8. a temperature sensor; 9. adjusting a rod; 10. adjusting the nut; 11. a temperature sensitive probe; 12. a cooling tube; 13. a refrigerator.

Detailed Description

To achieve the above object, the present invention provides the following embodiments and examples: a double dynamic cross-linked pH response type polyvinyl alcohol hydrogel comprises the following raw materials and components: the mass ratio of the hydrazide-terminated polyglycol to the coupling agent glutaraldehyde to the cross-linking agent boric acid to the carboxymethyl chitosan to the polyvinyl alcohol is 6-15:0.5-2:0.5-1.2:50-80: 100.

The preparation method of the hydrazide-terminated polyglycol comprises the following steps:

(1) adding anhydrous ethyl acetate solvent, polyethylene glycol 2000 and accelerant 4-dimethylaminopyridine into a reaction bottle, placing the reaction bottle above a base, fixedly connecting a condensing tube at the right lower part of the liquid nitrogen chamber, fixedly connecting a condensing chamber at the right end of the condensing tube, fixedly connecting a change-over valve in the condensing chamber, fixedly connecting a temperature sensor below the change-over valve, movably connecting an adjusting rod with the temperature sensor, movably connecting an adjusting nut below the adjusting rod, movably connecting a temperature-sensitive probe below the adjusting nut, fixedly connecting a cooling tube at the right side of the condensing chamber, fixedly connecting the right side of the cooling tube with a refrigerator, slowly dripping methanesulfonyl chloride at 0-5 ℃ in a nitrogen atmosphere, wherein the mass ratio of the three components is 1:0.15-0.25:0.2-0.3, heating to 15-30 ℃, stirring at a constant speed for reaction for 60-80h, and performing extraction, washing, recrystallization and drying processes on the solution to prepare the sulfonyl-terminated polyethylene glycol.

(2) Adding an acetone solvent, terminal sulfonyl ethylene glycol and methyl p-hydroxybenzoate into a reaction bottle, stirring and dissolving, adding an accelerator potassium carbonate, wherein the mass ratio of the acetone solvent to the terminal sulfonyl ethylene glycol to the methyl p-hydroxybenzoate is 1:4.2-5.5:0.7-0.85, placing the mixture into an oil bath pot, heating to 60-80 ℃, stirring at a constant speed for reaction for 30-40h, cooling the solution to room temperature, and performing extraction, washing, recrystallization and drying processes to prepare the terminal formate polyethylene glycol.

(3) Adding an ethyl acetate solvent and terminal formate-based polyethylene glycol into a reaction bottle, stirring and dissolving, then adding a hydrazine hydrate aqueous solution, wherein the mass ratio of the terminal formate-based polyethylene glycol to the hydrazine hydrate is 1:1.8-2.5, heating to 75-90 ℃, stirring at a constant speed for reaction for 30-40h, cooling the solution to room temperature, extracting, washing, recrystallizing and drying to obtain the terminal hydrazide-based polyglycol.

The preparation method of the double-dynamic cross-linked pH response type polyvinyl alcohol hydrogel comprises the following steps:

(1) adding a distilled water solvent, hydrazide-terminated polyglycol and carboxymethyl chitosan into a reaction bottle, stirring for dissolving, adding a coupling agent glutaraldehyde, heating to 50-70 ℃ in an oil bath pot, uniformly stirring for reaction for 6-10h, adding polyvinyl alcohol, wherein the mass ratio of hydrazide-terminated polyglycol to the coupling agent to the cross-linking agent to the carboxymethyl chitosan to the polyvinyl alcohol is 6-15:0.5-2:0.5-1.2:50-80:100, stirring at a constant speed for 20-40min, adding a cross-linking agent boric acid, cooling to 25-40 ℃, uniformly stirring for reaction for 5-10h, standing for 15-25h, filtering and washing the solution, and preparing the double-dynamic cross-linked pH-responsive polyvinyl alcohol hydrogel.