阅读说明：本技术 一种聚丙烯酰胺/壳聚糖接枝聚噻吩互穿网络水凝胶制备方法 (Preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel ) 是由 刘瑞来 陈慧玲 何欢 胡家朋 林皓 丁晓红 徐婕 苏丽鳗 于 2021-10-09 设计创作，主要内容包括：本发明公开了一种聚丙烯酰胺/壳聚糖接枝聚噻吩互穿网络水凝胶的制备方法。首先通过热致相分离法制备壳聚糖多孔纳米纤维,然后以壳聚糖多孔纳米纤维为骨架,将丙烯酰胺以互穿网络的形式聚合,得到聚丙烯酰胺/壳聚糖互穿网络水凝胶。最后将噻吩接枝到壳聚糖上,得到聚丙烯酰胺/壳聚糖接枝聚噻吩互穿网络水凝胶。利用壳聚糖多孔纳米纤维的高孔隙率和大比表面积,从而大大提高了导电水凝胶的孔隙率和比表面积,有利于提高导电水凝胶与电解液之间的浸润性,从而提高其比电容。(The invention discloses a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel. Firstly, preparing chitosan porous nano-fiber by a thermally induced phase separation method, then polymerizing acrylamide in an interpenetrating network form by taking the chitosan porous nano-fiber as a framework to obtain polyacrylamide/chitosan interpenetrating network hydrogel. Finally, thiophene is grafted to chitosan to obtain polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel. The high porosity and the large specific surface area of the chitosan porous nanofiber are utilized, so that the porosity and the specific surface area of the conductive hydrogel are greatly improved, the wettability between the conductive hydrogel and electrolyte is favorably improved, and the specific capacitance of the conductive hydrogel is improved.)

1. A preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel is characterized by comprising the following steps:

s1, preparing chitosan porous nanofiber;

s2, dispersing the chitosan porous nano-fiber in distilled water, adding acrylamide, N-methylene bisacrylamide and ammonium persulfate, and initiating a polymerization reaction by using ultraviolet light under the protection of nitrogen to obtain polyacrylamide/chitosan interpenetrating network hydrogel;

s3, soaking the polyacrylamide/chitosan interpenetrating network hydrogel in thiophene, transferring the polyacrylamide/chitosan interpenetrating network hydrogel adsorbed with thiophene into an iron trichloride aqueous solution after 24 hours, and carrying out polymerization reaction at a certain temperature to obtain the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel.

2. The preparation method of the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel according to claim 1, wherein the preparation method of the chitosan porous nanofiber comprises the following steps:

dissolving polyvinyl alcohol in distilled water to obtain a reaction solution A, and dissolving chitosan in an ethanol-water-acetic acid mixed solvent to obtain a reaction solution B;

uniformly mixing the reaction liquid A and the reaction liquid B to obtain quenching liquid;

quenching the quenching liquid at-30 to-10 ℃, soaking the product in an aqueous solution of sodium hydroxide, washing the product with distilled water until the pH value is neutral, freeze-drying the product at-23 ℃ for 4 hours, and finally freeze-drying the product at-50 ℃ to obtain chitosan/polyvinyl alcohol nanofibers;

and soaking the chitosan/polyvinyl alcohol nano-fiber in distilled water at the temperature of 80-90 ℃ to hydrolyze and remove polyvinyl alcohol, thereby obtaining the chitosan porous nano-fiber.

3. The preparation method of the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel according to claim 2, wherein the mass concentration of polyvinyl alcohol in the reaction solution A is 1.5-2.5%; in the solution B, the mass concentration of chitosan is 0.5-2.5%; the mass concentration of the sodium hydroxide solidification solution is 1-1.5%; the quenching time is 10-15 h.

4. The preparation method of the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel according to claim 2 or 3, wherein the volume ratio of ethanol to water in the ethanol-water-acetic acid mixed solvent is (5-7):

(3-6), the mass concentration of the acetic acid is 1%.

5. The preparation method of the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel according to claim 1, wherein the mass ratio of the acrylamide, the N, N-methylene bisacrylamide and the ammonium persulfate in the step S2 is (150-300): (2-4): (5-10).

6. The method for preparing the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel according to claim 1, wherein the wavelength of the ultraviolet light in step S2 is 365 nm.

7. The preparation method of the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel according to claim 1, wherein the molar concentration of the ferric trichloride aqueous solution in the step S3 is 0.8-1.2 mol/L; the temperature of the polymerization reaction is 3-5 ℃, and the reaction time is 10-15 h.

Technical Field

The invention relates to a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel, belonging to the technical field of electrochemical materials.

Background

The hydrogel contains a large number of hydrophilic groups, and can absorb three-dimensional network polymers which swell by water without dissolving. The conductive polymer is also called organic metal, and is a conductive polymer with a highly conjugated structure, and mainly comprises polyaniline, polypyrrole, polythiophene, copolymer and derivative thereof, and the like. Polythiophenes have good electrical conductivity and biocompatibility, are susceptible to chemical modification, and are of great interest. The conductive hydrogel is a novel hydrogel organically combining a hydrophilic matrix and a conductive medium, has high flexibility, adjustable mechanical property and excellent electrochemical property, and has wide application prospect in the fields of flexible electronic equipment and the like. The preparation methods of the current conductive hydrogel are mainly divided into three methods, namely 1) conductive polymers are introduced into the hydrogel to form polymer hydrogel; 2) introducing conductive particles into the hydrogel to form a composite hydrogel; 3) conductive ions are introduced into the hydrogel to form the ionic hydrogel (wangsheng, et al, preparation and application research progress of the conductive hydrogel, chemical development, 2021, 40, 2646). For example, Chen et al, which uses a PANI network formed by phytic acid crosslinking with a polyacrylic network, synthesizes an extremely ductile and electrically conductive hydrogel through physical entanglement, hydrogen bonding and ionic interaction (Wang Z W, et al, external mechanical and electrical conductive hydrogels with a metallic synthetic network for a commercial cable sensor. journal of Materials Chemistry C,2018,6, 9200). Chitosan is a product of chitin N-deacetylation, has biodegradability, cell affinity, biological effect and the like, and is considered as a functional biomaterial with greater application potential than fibers. However, the synthesis of the conductive hydrogel by grafting the chitosan onto the conductive polymer is rarely reported.

The invention content is as follows:

the invention aims to provide a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel, which aims to solve the problems in the prior art.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel comprises the following steps:

s1, preparing chitosan porous nanofiber;

s2, dispersing the chitosan porous nano-fiber in distilled water, adding acrylamide, N-methylene bisacrylamide and ammonium persulfate, and initiating a polymerization reaction by using ultraviolet light under the protection of nitrogen to obtain polyacrylamide/chitosan interpenetrating network hydrogel;

s3, soaking the polyacrylamide/chitosan interpenetrating network hydrogel in thiophene, transferring the polyacrylamide/chitosan interpenetrating network hydrogel adsorbed with thiophene into an iron trichloride aqueous solution after 24 hours, and carrying out polymerization reaction at a certain temperature to obtain the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel.

As a preferred scheme, the preparation method of the chitosan porous nanofiber comprises the following steps:

dissolving polyvinyl alcohol in distilled water to obtain a reaction solution A, and dissolving chitosan in an ethanol-water-acetic acid mixed solvent to obtain a reaction solution B;

uniformly mixing the reaction liquid A and the reaction liquid B to obtain quenching liquid;

quenching the quenching liquid at-30 to-10 ℃, soaking the product in an aqueous solution of sodium hydroxide, washing the product with distilled water until the pH value is neutral, freeze-drying the product at-23 ℃ for 4 hours, and finally freeze-drying the product at-50 ℃ to obtain chitosan/polyvinyl alcohol nanofibers;

and soaking the chitosan/polyvinyl alcohol nano-fiber in distilled water at the temperature of 80-90 ℃ to hydrolyze and remove polyvinyl alcohol, thereby obtaining the chitosan porous nano-fiber.

Preferably, in the reaction solution A, the mass concentration of the polyvinyl alcohol is 1.5-2.5%; in the solution B, the mass concentration of chitosan is 0.5-2.5%; the mass concentration of the sodium hydroxide solidification solution is 1-1.5%; the quenching time is 10-15 h.

Preferably, in the ethanol-water-acetic acid mixed solvent, the volume ratio of ethanol to water is (5-7): (3-6), the mass concentration of the acetic acid is 1%.

Preferably, in the step S2, the mass ratio of the acrylamide to the N, N-methylene-bisacrylamide to the ammonium persulfate is (150-300): (2-4): (5-10).

Preferably, the wavelength of the ultraviolet light in step S2 is 365 nm.

Preferably, the molar concentration of the ferric trichloride aqueous solution in the step S3 is 0.8-1.2 mol/L; the temperature of the polymerization reaction is 3-5 ℃, and the reaction time is 10-15 h.

The mechanism of the invention is as follows:

firstly, preparing chitosan/polyvinyl alcohol nano-fibers through thermally induced phase separation, and then soaking the chitosan/polyvinyl alcohol nano-fibers in hot water to remove polyvinyl alcohol, so as to obtain the chitosan porous nano-fibers. Soaking the chitosan porous nano-fiber in acrylamide, using N, N-methylene bisacrylamide as a cross-linking agent and ammonium persulfate as an initiator, and initiating acrylamide polymerization by ultraviolet irradiation to obtain the polyacrylamide/chitosan interpenetrating network hydrogel. And finally, soaking the polyacrylamide/chitosan interpenetrating network hydrogel in thiophene, taking ferric trichloride as an initiator, and grafting and polymerizing thiophene onto the chitosan to obtain the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel.

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

1. the chitosan porous nanofiber is used as a framework, and acrylamide is polymerized in an interpenetrating network form to form polyacrylamide/chitosan interpenetrating network hydrogel, so that the flexibility of the conductive hydrogel is greatly improved.

2. By utilizing the advantages of high porosity, large specific surface area and the like of the chitosan porous nanofiber, thiophene is grafted to chitosan, so that the porosity and the specific surface area of the conductive hydrogel are greatly improved, the wettability between the conductive hydrogel and electrolyte is favorably improved, and the specific capacitance of the conductive hydrogel is improved.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a scanning electron microscope image of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel prepared in example 1 of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1

The embodiment provides a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel, which specifically comprises the following steps:

1) preparation of CS porous nanofiber

0.1g of polyvinyl alcohol (PVA) was added to 5g of distilled water, and dissolved by magnetic stirring at 90 ℃ to form a uniform transparent solution, thereby obtaining a reaction solution A. Adding 0.1g of Chitosan (CS) into 5g of ethanol-water-acetic acid mixed solvent (ethanol-water-acetic acid mixed solvent, volume ratio of ethanol to water is 7:3, mass concentration of acetic acid is 1%), and magnetically stirring and dissolving at normal temperature to obtain reaction liquid B. And mixing and stirring the reaction liquid A and the reaction liquid B at normal temperature to form quenching liquid. And (2) pouring 8g of the quenching liquid into a culture dish, putting the culture dish into an ultralow-temperature refrigerator at minus 30 ℃ for quenching for 12h, after quenching, slowly pouring the NaOH solidification liquid with the mass concentration of 1% into the culture dish from the edge of the culture dish for soaking for 6h, after soaking, washing the pH value to be neutral with distilled water, pouring out the water, freezing the sample at minus 23 ℃ for 4h, and then, freeze-drying at minus 50 ℃ to obtain the CS/PVA nanofiber. And soaking the CS/PVA nano-fiber in distilled water at 90 ℃ for 5 hours to remove the PVA, thereby obtaining the CS porous nano-fiber.

2) Preparation of PAM/CS interpenetrating network polymer hydrogel

0.5g of CS porous nanofibers was dispersed in 10g of distilled water to obtain a CS porous nanofiber dispersion. To the dispersion were added 2.5g of Acrylamide (AM), 0.02g N, N-Methylenebisacrylamide (MBA) and 0.05g of ammonium persulfate, and the mixture was magnetically stirred at ordinary temperature. And under the protection of nitrogen, irradiating the mixed solution for 10min under a 365nm ultraviolet lamp to obtain polyacrylamide/chitosan (PAM/CS) interpenetrating network hydrogel.

3) Preparation of PAM/CS-g-PTh interpenetrating network hydrogel

Soaking 1g of PAM/CS interpenetrating network polymer hydrogel in 0.5g of thiophene (Th) for 24h at normal temperature to adsorb the thiophene into the hydrogel, and then soaking the hydrogel in 0.8mol/L of ferric trichloride aqueous solution at the reaction temperature of 4 ℃ for 12h to obtain the polyacrylamide/chitosan grafted polythiophene (PAM/CS-g-PTy) interpenetrating network hydrogel.

The morphology of the PAM/CS-g-PTy interpenetrating network hydrogel prepared in example 1 is shown in FIG. 1. The hydrogel had a porosity of 95.1% and a specific surface area of 18.91m²The specific conductivity was 1.28S/m. The specific capacitance was 167F/g at a current density of 1A/g.

Example 2

The embodiment provides a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel, which specifically comprises the following steps:

1) preparation of CS porous nanofiber

0.08g of polyvinyl alcohol (PVA) was added to 5g of distilled water, and dissolved by magnetic stirring at 90 ℃ to form a uniform transparent solution, thereby obtaining a reaction solution A. Adding 0.08g of Chitosan (CS) into 5g of ethanol-water diluted-acetic acid mixed solvent (the volume ratio of ethanol to water in the ethanol-water diluted-acetic acid mixed solvent is 6:4, the mass concentration of acetic acid is 1%), and magnetically stirring and dissolving at normal temperature to obtain reaction liquid B. And mixing and stirring the reaction liquid A and the reaction liquid B at normal temperature to form quenching liquid. And (2) pouring 8g of the quenching liquid into a culture dish, putting the culture dish into an ultralow-temperature refrigerator at minus 25 ℃ for quenching for 10 hours, after quenching, slowly pouring the NaOH solidification liquid with the mass concentration of 1.2% into the culture dish from the edge of the culture dish for soaking for 6 hours, after soaking, washing the pH value to be neutral with distilled water, pouring out the water, freezing the sample at minus 23 ℃ for 4 hours, and freeze-drying at minus 50 ℃ to obtain the CS/PVA nanofiber. And soaking the CS/PVA nano-fiber in distilled water at 90 ℃ for 5 hours to remove the PVA, thereby obtaining the CS porous nano-fiber.

2) Preparation of PAM/CS interpenetrating network polymer hydrogel

0.5g of CS porous nanofibers was dispersed in 10g of distilled water to obtain a CS porous nanofiber dispersion. To the dispersion were added 2.8g of Acrylamide (AM), 0.03g N, N-Methylenebisacrylamide (MBA) and 0.06g of ammonium persulfate, and the mixture was magnetically stirred at ordinary temperature. And under the protection of nitrogen, irradiating the mixed solution for 10min under a 365nm ultraviolet lamp to obtain polyacrylamide/chitosan (PAM/CS) interpenetrating network hydrogel.

3) Preparation of PAM/CS-g-PTh interpenetrating network hydrogel

Soaking 1g of PAM/CS interpenetrating network polymer hydrogel in 0.5g of thiophene (Th) for 24h at normal temperature to adsorb the thiophene into the hydrogel, and then soaking the hydrogel in 1mol/L of ferric trichloride aqueous solution at the reaction temperature of 5 ℃ for 15h to obtain the polyacrylamide/chitosan grafted polythiophene (PAM/CS-g-PTy) interpenetrating network hydrogel.

The PAM/CS-g-PTy interpenetrating network hydrogel prepared in example 2 has a porosity of 94.8% and a specific surface area of 17.44m²The specific conductivity was 1.42S/m. The specific capacitance was 163F/g under the condition of a current density of 1A/g.

Example 3

The embodiment provides a preparation method of polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel, which specifically comprises the following steps:

1) preparation of CS porous nanofiber

0.12g of polyvinyl alcohol (PVA) was added to 5g of distilled water, and dissolved by magnetic stirring at 90 ℃ to form a uniform transparent solution, thereby obtaining a reaction solution A. Adding 0.12g of Chitosan (CS) into 5g of ethanol-water diluted-acetic acid mixed solvent (the volume ratio of ethanol to water is 5:5, the mass concentration of acetic acid is 1 percent) and magnetically stirring for dissolving at normal temperature to obtain reaction liquid B. And mixing and stirring the reaction liquid A and the reaction liquid B at normal temperature to form quenching liquid. And (2) pouring 8g of the quenching liquid into a culture dish, putting the culture dish into an ultralow-temperature refrigerator at-20 ℃ for quenching for 15h, after quenching, slowly pouring the NaOH solidification liquid with the mass concentration of 1.5% into the culture dish from the edge of the culture dish for soaking for 6h, after soaking, washing the pH value to be neutral with distilled water, pouring out the water, freezing the sample at-23 ℃ for 4h, and freeze-drying at-50 ℃ to obtain the CS/PVA nanofiber. And soaking the CS/PVA nano-fiber in distilled water at 90 ℃ for 5 hours to remove the PVA, thereby obtaining the CS porous nano-fiber.

2) Preparation of PAM/CS interpenetrating network polymer hydrogel

0.5g of CS porous nanofibers was dispersed in 10g of distilled water to obtain a CS porous nanofiber dispersion. To the dispersion were added 2g of Acrylamide (AM), 0.02g of N, N-Methylenebisacrylamide (MBA) and 0.08g of ammonium persulfate, and the mixture was magnetically stirred at ordinary temperature. And under the protection of nitrogen, irradiating the mixed solution for 10min under a 365nm ultraviolet lamp to obtain polyacrylamide/chitosan (PAM/CS) interpenetrating network hydrogel.

3) Preparation of PAM/CS-g-PTh interpenetrating network hydrogel

Soaking 1g of PAM/CS interpenetrating network polymer hydrogel in 0.5g of thiophene (Th) for 24h at normal temperature to adsorb the thiophene into the hydrogel, and then soaking the hydrogel in 1.2mol/L of ferric trichloride aqueous solution at the reaction temperature of 3 ℃ for 12h to obtain the polyacrylamide/chitosan grafted polythiophene (PAM/CS-g-PTy) interpenetrating network hydrogel.

PAM/CS-The g-PTy interpenetrating network hydrogel has a porosity of 93.9% and a specific surface area of 18.79m²The specific conductivity was 1.31S/m. The specific capacitance was 171F/g at a current density of 1A/g.

Comparative example 1

This comparative example differs from example 1 in that: step 1 is omitted, and commercially available chitosan powder is directly used for replacing the chitosan porous nanofiber in step 2, so that the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel is finally obtained. The hydrogel had a porosity of 88.1% and a specific surface area of 7.88m²The specific conductivity was 1.21S/m. The specific capacitance was 97F/g at a current density of 1A/g.

Comparative example 2

This comparative example differs from example 1 in that: step 2 is omitted, and chitosan porous nano-fibers are directly soaked in thiophene in step 3 to finally obtain chitosan grafted polythiophene. The porosity of the material is 85.1%, and the specific surface area is 16.12m²The specific conductivity was 1.01S/m. The specific capacitance was 115F/g at a current density of 1A/g.

Comparative example 3

This comparative example differs from example 1 in that: and (3) the addition amount of the polyvinyl alcohol in the step (1) is 0, and finally the polyacrylamide/chitosan grafted polythiophene interpenetrating network hydrogel is obtained. The hydrogel had a porosity of 90.1% and a specific surface area of 10.11m²The specific conductivity was 1.09S/m. The specific capacitance was 108F/g at a current density of 1A/g.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.