CN116217978B - A polyaniline-based flexible conductive hydrogel and preparation method thereof - Google Patents

Abstract

The invention discloses polyaniline-based flexible conductive hydrogel and a preparation method thereof, and belongs to the technical field of flexible electronic materials. Firstly, preparing pH responsive poly (acrylamide-co-sodium acrylate) substrate hydrogel; swelling the substrate hydrogel, and then placing the substrate hydrogel in an aniline hydrochloride solution for full adsorption; and adding the mixed solution of ammonium persulfate and phytic acid in batches to perform gradual reaction to obtain the polyaniline-based flexible conductive hydrogel. The invention utilizes the swelling-shrinking effect of the substrate hydrogel and adopts the dynamic control means of a gradual reaction mode, and the prepared polyaniline-based flexible conductive hydrogel has excellent electrochemical performance, can be used for electrode materials of flexible energy storage devices, and has simple preparation process, easy operation and wide development prospect.

Description

A polyaniline-based flexible conductive hydrogel and preparation method thereof

Technical Field

The invention belongs to the technical field of flexible electronic materials and relates to a conductive functional polymer hydrogel, in particular to a polyaniline-based flexible conductive hydrogel and a preparation method thereof.

Background technique

In recent years, with the rapid development of flexible wearable electronic technology, flexible energy storage devices such as flexible supercapacitors have aroused widespread interest, among which flexible electrode materials are the key. Polyaniline has the advantages of good conductivity, high theoretical specific capacitance, low price and easy availability, but poor flexibility, while hydrogel has excellent flexibility, mechanical properties and biocompatibility. Therefore, the combination of polyaniline and hydrogel to prepare conductive hydrogel-based flexible electrode materials has attracted much attention. However, in the preparation process of polyaniline-based conductive hydrogel, the permeability of aniline into the hydrogel is poor, and it is often necessary to add a template to form pores or use a high concentration of aniline for in-situ polymerization. CN 110157013 A discloses that on the basis of synthesizing a pH-responsive poly(acrylamide-co-sodium acrylate) copolymer substrate hydrogel (ASH), a porous ASH hydrogel is prepared by swelling-freeze-thaw treatment, which solves the problem of aniline permeability, but the freeze-thaw process has high energy consumption.

Summary of the invention

The purpose of the present invention is to provide a polyaniline-based flexible conductive hydrogel and a preparation method thereof in view of the deficiencies of the prior art. The polyaniline-based flexible conductive hydrogel prepared by using the swelling-contraction effect of the base hydrogel and the kinetic control means of the stepwise reaction mode has excellent electrochemical properties and can be used as an electrode material for a flexible energy storage device. The preparation process is simple and easy to operate, and the development prospects are broad.

To achieve the above object, the present invention adopts the following technical solution:

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Preparation of pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel;

(2) The base hydrogel is swelled and then placed in a hydrochloric acid aniline solution for full adsorption;

(3) Adding a mixed solution of ammonium persulfate and phytic acid to the above solution in batches for gradual reaction to obtain the polyaniline-based flexible conductive hydrogel.

In step (1), 1 g of acrylamide is dissolved in 2 mL of deionized water, 3 mL of an acrylic acid solution having a neutralization degree of 50 mol% is added, and then 1 mL of a 1 wt% ammonium persulfate solution and 0.1 mL of a 1 wt% N,N'-methylenebisacrylamide solution are added. The mixture is stirred evenly and reacted at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

In step (2), the base hydrogel prepared in step (1) is placed in deionized water to fully swell, then immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min, and then cooled to 0°C.

In step (3), 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid are added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C. Then, the mixed solution of ammonium persulfate and phytic acid is added to the aniline hydrochloride solution in which the base hydrogel is soaked in step (2) in 1 to 8 times with an interval of 1 to 3 hours each time. The polymerization reaction is carried out for 48 hours, and the mixture is washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel.

In the present invention, the polymerization reaction environment of aniline is acidic, and the reaction rate is fast. At the same time, the pH-responsive poly (acrylamide-co-sodium acrylate) substrate hydrogel shrinks in an acidic environment, resulting in a dense layer of polyaniline on the outside of the hydrogel, preventing the aniline from further penetrating into the hydrogel. Therefore, the present invention proposes a stepwise reaction method of adding a mixed solution of ammonium persulfate and phytic acid in batches, which reduces the aggregation of aniline on the gel surface and promotes the penetration of aniline into the hydrogel by controlling the shrinkage rate of the substrate hydrogel and the polymerization rate of aniline, and gradually shrinks to make the polyaniline inside the hydrogel denser, and strengthens the interaction between polyaniline and the hydrogel skeleton, thereby constructing a regular and dense three-dimensional conductive network, and significantly improving the electrochemical properties of the conductive hydrogel.

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

(1) The present invention adopts a step-by-step reaction method, which can effectively promote the penetration of aniline into the hydrogel without freeze-thaw cycles, thereby saving energy and reducing consumption. At the same time, it can also avoid the structural defects of the base hydrogel caused by repeated crystallization-thawing during multiple freeze-thaw cycles.

(2) The present invention utilizes the pH response characteristics of poly(acrylamide-co-sodium acrylate)-based hydrogel that shrinks in an acidic environment after swelling, and adds a mixed solution of ammonium persulfate and phytic acid in batches to control the shrinkage rate of the base hydrogel and the polymerization rate of aniline. This not only enhances the permeability of aniline, but also makes the polyaniline conductive network more regular and dense through gradual shrinkage, thereby significantly enhancing the electrochemical performance.

(3) The present invention utilizes the swelling-contraction effect of the base hydrogel and adopts a step-by-step reaction kinetic control method to prepare a polyaniline-based flexible conductive hydrogel with excellent electrochemical properties. It can be used as an electrode material for flexible energy storage devices. The preparation process is simple and easy to operate, and has broad development prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a picture of the conductive hydrogel prepared in Example 1 making an LED emit light;

FIG2 is a comparison diagram of constant current charge and discharge curves of the conductive hydrogels prepared in Example 1 and Comparative Example 1;

FIG3 is a scanning electron microscope image of the surface of the conductive hydrogel prepared in Example 1.

Detailed ways

In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

Example 1

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C. The mixed solution of ammonium persulfate and phytic acid was then added to the solution system of step (2) for 6 times with an interval of 1 h each time, and the polymerization reaction was carried out for 48 hours. The product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel.

The conductivity of the polyaniline-based flexible conductive hydrogel reaches 5.18 S/m, which can make LEDs emit light (Figure 1). When the current density is 1 mA/ ^cm2 , the area specific capacitance of the flexible conductive hydrogel is 3750 mF/ ^cm2 (Figure 2), and the capacitance retention rate reaches 90% after 1000 charge and discharge cycles. From Figure 3, wrinkles formed by the shrinkage of the conductive hydrogel can be seen, and it can be clearly observed that polyaniline is coated on the hydrogel skeleton. These show that the polyaniline-based flexible conductive hydrogel prepared by the step-by-step reaction method of the present invention has excellent conductive and electrochemical properties, and the step-by-step shrinkage can promote the efficient compounding of polyaniline and the hydrogel skeleton, thereby constructing a regular and dense three-dimensional conductive network.

Comparative Example 1

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C. The mixed solution of ammonium persulfate and phytic acid was then added to the solution system of step (2) by a one-time feeding method for polymerization reaction for 48 h. The product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel. The conductivity of the conductive hydrogel was 0.49 S/m, and the area specific capacitance was 966.25 mF/cm ² at a current density of 1 mA/cm ^2. The capacitance retention rate reached 85% after 1000 charge and discharge cycles.

Compared with Example 1, Comparative Example 1 adopts a one-time feeding method to add a mixed solution of ammonium persulfate and phytic acid. From the comparison of the constant current charge and discharge curves, it can be seen that the area specific capacitance of Example 1 (3750 mF/cm ² ) is much greater than that of Comparative Example 1 (961.25 mF/cm ² ). This is mainly because the addition of ammonium persulfate initiator and phytic acid in batches in Example 1 can reduce the aggregation of polyaniline on the gel surface caused by too fast reaction rate and promote the penetration of aniline. At the same time, the gradual shrinkage of the pH-responsive substrate hydrogel during the polymerization process is utilized to promote the efficient compounding of polyaniline and the hydrogel skeleton, so that Example 1 exhibits excellent electrochemical performance.

Example 2

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C. The mixed solution of ammonium persulfate and phytic acid was then added to the solution system of step (2) twice, each time at an interval of 2 h, for polymerization reaction for 48 h. The product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel. The conductivity of the conductive hydrogel was 0.48 S/m, and the area specific capacitance at a current density of 1 mA/ ^cm2 was 1337.50 mF/ ^cm2 .

Example 3

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C. The mixed solution of ammonium persulfate and phytic acid was then added to the solution system of step (2) three times with an interval of 2 h each time for polymerization reaction for 48 h. The product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel. The conductivity of the conductive hydrogel was 0.76 S/m, and the area specific capacitance at a current density of 1 mA/ ^cm2 was 1887.50 mF/ ^cm2 .

Example 4

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C, and then the mixed solution of ammonium persulfate and phytic acid was added to the solution system of step (2) for 48 hours at intervals of 2 hours, and the product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel. The conductivity of the conductive hydrogel was 1.15 S/m, and the area specific capacitance at a current density of 1 mA/ ^cm2 was 2325 mF/ ^cm2 .

Example 5

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C, and then the mixed solution of ammonium persulfate and phytic acid was added to the solution system of step (2) twice, each time at an interval of 3 hours, for polymerization reaction for 48 hours, and the product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel. The conductivity of the conductive hydrogel is 0.76 S/m, and the area specific capacitance at a current density of 1 mA/ ^cm2 is 1150 mF/ ^cm2 .

Example 6

A method for preparing a polyaniline-based flexible conductive hydrogel comprises the following steps:

(1) Weigh 1 g of acrylamide, dissolve it in 2 mL of deionized water, add 3 mL of 50 mol% neutralization degree acrylic acid solution, then add 1 mL of 1 wt% ammonium persulfate solution and 0.1 mL of 1 wt% N,N'-methylenebisacrylamide solution, stir evenly and react at 65 °C for 5 h to obtain the pH-responsive poly(acrylamide-co-sodium acrylate)-based hydrogel.

(2) First, the pH-responsive substrate hydrogel was placed in deionized water to fully swell, and then the swollen hydrogel was immersed in 30 mL of 0.1 mol/L aniline hydrochloride solution for 30 min and then cooled to 0 °C.

(3) 0.4564 g of ammonium persulfate and 300 μL of 70 wt% phytic acid were added to 2 mL of deionized water to prepare a mixed solution and cooled to 0°C. The mixed solution of ammonium persulfate and phytic acid was then added to the solution system of step (2) three times with an interval of 3 hours each time for polymerization reaction for 48 hours. The product was washed with deionized water to obtain the polyaniline-based flexible conductive hydrogel. The conductivity of the conductive hydrogel was 0.92 S/m, and the area specific capacitance at a current density of 1 mA/ ^cm2 was 2025 mF/ ^cm2 .

The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims (4)

1. A preparation method of polyaniline-based flexible conductive hydrogel is characterized by comprising the following steps: the method comprises the following steps:

(1) Preparing a pH-responsive poly (acrylamide-co-sodium acrylate) substrate hydrogel;

(2) Swelling the substrate hydrogel, and then placing the substrate hydrogel in an aniline hydrochloride solution for full adsorption;

(3) And adding the mixed solution of ammonium persulfate and phytic acid in batches to perform gradual reaction to prepare the polyaniline-based flexible conductive hydrogel.

2. The method according to claim 1, characterized in that: in the step (1), 1g acrylamide is dissolved in 2 mL deionized water, 3 mL acrylic acid solution with the neutralization degree of 50mol percent is added, then 1 mL of 1wt% ammonium persulfate solution and 0.1 mL of 1wt% N, N ^, -methylene bisacrylamide solution are added, and after uniform stirring, the mixture is reacted at 65 ℃ for 5 h, so that the pH-responsive poly (acrylamide-co-sodium acrylate) base hydrogel is prepared.

3. The method according to claim 1, characterized in that: in the step (2), the substrate hydrogel prepared in the step (1) is put into deionized water for full swelling, then is put into 30 mL of 0.1mol/L aniline hydrochloride solution for soaking 30 min, and is then cooled to 0 ℃.

4. A polyaniline-based flexible conductive hydrogel made according to the method of any one of claims 1-3.