阅读说明：本技术 一种复合导电水凝胶的制备方法 (preparation method of composite conductive hydrogel ) 是由 李忠勇 于 2019-08-05 设计创作，主要内容包括：本发明属于高分子材料制备技术领域,具体涉及一种复合导电水凝胶的制备方法。本发明以水凝胶预聚体、丙烯酰胺、过硫酸铵、N,N-亚甲基双丙烯酰胺等混合即得复合导电水凝胶。本发明的自制导电填料为水凝胶预聚体的氧化聚合提供了纳米空间有限氧化环境,从而防止了邻苯二酚基团的过度氧化,形成的水凝胶预聚体中保留了大量酚羟基,由于水凝胶预聚体为聚丙烯酰胺网络中引入了大量酚羟基,因此赋予了此复合导电良好的生物相容性,而且在水凝胶预聚体聚合过程中,导电填料和水凝胶之间形成了物理锚固作用,导电填料还增加了水凝胶的力学性能,最终本发明制得的复合导电水凝胶不仅导电性能和力学性能优异,生物相容性也极佳,具有广阔的应用前景。(The invention belongs to the technical field of preparation of high polymer materials, and particularly relates to a preparation method of a composite conductive hydrogel. The composite conductive hydrogel is prepared by mixing hydrogel prepolymer, acrylamide, ammonium persulfate, N-methylene-bisacrylamide and the like. The self-made conductive filler provides a nano space limited oxidation environment for the oxidative polymerization of the hydrogel prepolymer, so that excessive oxidation of catechol groups is prevented, a large number of phenolic hydroxyl groups are reserved in the formed hydrogel prepolymer, and the hydrogel prepolymer introduces a large number of phenolic hydroxyl groups into a polyacrylamide network, so that the composite conductive hydrogel is endowed with good biocompatibility, a physical anchoring effect is formed between the conductive filler and the hydrogel in the polymerization process of the hydrogel prepolymer, the conductive filler also increases the mechanical property of the hydrogel, and finally the composite conductive hydrogel prepared by the invention has excellent conductivity and mechanical property, excellent biocompatibility and wide application prospect.)

1. a preparation method of composite conductive hydrogel is characterized by comprising the following specific preparation steps:

Weighing a hydrogel prepolymer, acrylamide, ammonium persulfate, N-methylene bisacrylamide and tetramethylethylenediamine, mixing, putting into a beaker, and stirring in an ice water bath for reaction for 10-15 min to obtain the composite conductive hydrogel;

The preparation steps of the hydrogel prepolymer are as follows:

(1) mixing a polyvinyl alcohol solution with the mass fraction of 10% and a 3, 4-dihydroxybenzoic acid solution with the mass fraction of 30%, putting into a reaction kettle, heating to 70-80 ℃, and stirring for reaction for 3-5 hours to obtain a reaction solution;

(2) mixing the self-made conductive filler with the reaction liquid, putting the mixture into a reaction kettle, continuously adding catechol oxidase into the reaction kettle, and stirring and reacting at the temperature of 30-40 ℃ at the rotating speed of 700-800 r/min for 4-6 hours to obtain a hydrogel prepolymer;

The preparation steps of the self-made conductive filler are as follows:

(1) soaking flax fibers in biogas liquid for 1-2 h, taking out, putting into a mildew chamber, standing for mildew for 1-2 weeks, transferring the mildewed flax fibers into a fermentation tank, adding water with the same mass as the mildewed flax fibers into the fermentation tank, uniformly stirring, sealing the opening of the tank, and standing for fermentation at 35-45 ℃ for 3-5 days;

(2) after the fermentation is finished, filtering and separating to obtain fermentation filter residues, putting the fermentation filter residues into a carbonization furnace, carbonizing at 200-300 ℃ for 1-2 hours to obtain a self-made porous carbon material, and mixing the self-made porous carbon material with a nickel nitrate solution with the mass fraction of 30% to obtain a mixed solution;

(3) And (3) moving the mixed solution into an ultrasonic oscillator, carrying out ultrasonic oscillation dipping and mixing for 1-2 hours at the frequency of 40-50 kHz, filtering after the ultrasonic oscillation dipping, separating to obtain dipping filter residues, putting the dipping filter residues into a sintering furnace, carrying out sintering treatment under the protection of nitrogen, and obtaining the self-made conductive filler after sintering.

2. The method for preparing the composite conductive hydrogel according to claim 1, wherein the method comprises the following steps: in the specific preparation steps of the composite conductive hydrogel, by weight, 100-120 parts of hydrogel prepolymer, 60-70 parts of acrylamide, 1-2 parts of ammonium persulfate, 30-40 parts of N, N-methylene bisacrylamide and 3-5 parts of tetramethyl ethylene diamine are used.

3. The method for preparing the composite conductive hydrogel according to claim 1, wherein the method comprises the following steps: in the preparation step (1) of the hydrogel prepolymer, the mass ratio of a polyvinyl alcohol solution with the mass fraction of 10% to a 3, 4-dihydroxybenzoic acid solution with the mass fraction of 30% is 5: 1.

4. the method for preparing the composite conductive hydrogel according to claim 1, wherein the method comprises the following steps: in the step (2) of preparing the hydrogel prepolymer, the mass ratio of the self-made conductive filler to the reaction liquid is 1:10, and the addition amount of the catechol oxidase is 5% of the mass of the reaction liquid.

5. the method for preparing the composite conductive hydrogel according to claim 1, wherein the method comprises the following steps: in the step (1) of preparing the self-made conductive filler, the temperature of a mildew room is 40-50 ℃, and the relative humidity of air is 70-80%.

6. The method for preparing the composite conductive hydrogel according to claim 1, wherein the method comprises the following steps: in the step (2) of preparing the self-made conductive filler, the mass ratio of the self-made porous carbon material to the nickel nitrate solution with the mass fraction of 30% is 1: 5.

7. the method for preparing the composite conductive hydrogel according to claim 1, wherein the method comprises the following steps: in the step (3) of preparing the self-made conductive filler, the sintering treatment temperature is 400-500 ℃ under the protection of nitrogen, and the sintering treatment time is 4-6 h.

Technical Field

the invention belongs to the technical field of preparation of high polymer materials, and particularly relates to a preparation method of a composite conductive hydrogel.

Background

Hydrogels are soft materials composed of water and a three-dimensional polymer network. The crosslinking points in the network are chemical crosslinking points formed by covalent bonds or physical crosslinking points formed by non-covalent bonds such as ionic bonds, hydrogen bonds, hydrophobic interactions, coordination interactions and the like. It has soft property, fast swelling speed and certain shape maintaining effect. Generally, the polymer material contains a small amount of solid components and is loosely crosslinked, contains a large amount of water in the interior, has good biocompatibility and good responsiveness to external stimuli, and is widely applied to various fields of agriculture, mining industry, construction industry, medicine, cosmetics, petrochemical industry and the like.

Many natural polymer materials in nature are typical physical hydrogel materials, such as agar, chitosan, sodium alginate and the like, are in a stable gel state at normal temperature, and are converted into a solution by heating to a certain temperature. Conventional hydrogels are generally non-conductive and conductive hydrogels can be formed by incorporating conductive fillers or conductive polymers into the gel matrix to form a hydrogel with responsiveness and conductivity. Conductive nanomaterials such as carbon nanotubes, carbon black and metal nanoparticles are added to increase the electrical conductivity of the hydrogel. The conductive hydrogel combines the dual characteristics of the hydrogel and the conductive substance, and can have different conductivity intervals on the premise of keeping the dimensional stability, so that the conductive hydrogel can be applied to the fields of biological medicines, tissue engineering materials, biosensors and the like.

The conductive hydrogel comprises polyelectrolyte conductive hydrogel, conductive polymer-based hydrogel and the like. In recent years, there are more and more reports on the research in the field of conductive polymer hydrogels, and both synthetic polymers and natural polymers are used to prepare conductive hydrogels. The commonly used conductive polymers include polyacetylene, polyphenylene, polypyrrole, polyaniline, etc. Among the hydrogel precursor polymers that are commonly used are polyvinyl alcohol, cellulose, and other polymers that contain a large number of hydrophilic functional groups, such as hydroxyl groups, in the molecule.

However, the conductive hydrogel in the prior art has some problems that the preparation method is not simple enough, the mechanical strength is not sufficient, the conductivity is poor, the self-repairing performance is poor, the biocompatibility is poor, the viscoelasticity is not sufficient, the swelling property and the thermal stability cannot meet the requirements of practical application, particularly, the viscosity and the conductivity under a humid environment are difficult to be unified with each other, the optimal effect is difficult to achieve, and the use of the conductive hydrogel is limited to a certain extent. In addition, as the conductive filler is generally insoluble in water, the uniformity of the conductive filler in the hydrogel is not enough, and the conductivity and the mechanical property of the conductive hydrogel are directly influenced; the interaction force between part of the conductive filler and the hydrogel matrix is lacked, so that the conductive hydrogel structure is unstable, the conductive filler is easy to separate from the hydrogel matrix, and the mechanical property of the conductive hydrogel is influenced. Chinese patent CN102643375A discloses a method for preparing biocompatible photo-thermal response self-healing conductive hydrogel, which is prepared by compounding N, N-dimethylacrylamide monomer and graphene and initiating polymerization at room temperature. The conductive hydrogel prepared by taking the synthetic polymer as a raw material has good mechanical property and high response speed in an electric field, but the application of the synthetic polymer in the aspect of biological medicine is limited due to poor biocompatibility and biodegradability of the synthetic polymer.

Therefore, the conductive hydrogel material with excellent mechanical strength and functionality is prepared by a simple and easy method, the relation between the internal structure and each performance is explored, and the development of the systematic research of the aspects has important significance.

Disclosure of Invention

The invention mainly solves the technical problem, and provides a preparation method of composite conductive hydrogel aiming at the defects that the structure of the conductive hydrogel is unstable, the conductive filler is easy to separate from the hydrogel matrix, the electrical property and the mechanical property of the conductive hydrogel are influenced and the biocompatibility of the common hydrogel is poor due to the lack of interaction force between the conductive filler and the hydrogel matrix in the conventional conductive hydrogel.

In order to solve the technical problems, the technical problems to be solved by the invention are as follows:

the specific preparation steps of the composite conductive hydrogel are as follows:

weighing a hydrogel prepolymer, acrylamide, ammonium persulfate, N-methylene bisacrylamide and tetramethylethylenediamine, mixing, putting into a beaker, and stirring in an ice water bath for reaction for 10-15 min to obtain the composite conductive hydrogel;

The preparation steps of the hydrogel prepolymer are as follows:

(1) Mixing a polyvinyl alcohol solution with the mass fraction of 10% and a 3, 4-dihydroxybenzoic acid solution with the mass fraction of 30%, putting into a reaction kettle, heating to 70-80 ℃, and stirring for reaction for 3-5 hours to obtain a reaction solution;

(2) mixing the self-made conductive filler with the reaction liquid, putting the mixture into a reaction kettle, continuously adding catechol oxidase into the reaction kettle, and stirring and reacting at the temperature of 30-40 ℃ at the rotating speed of 700-800 r/min for 4-6 hours to obtain a hydrogel prepolymer;

The preparation steps of the self-made conductive filler are as follows:

(1) Soaking flax fibers in biogas liquid for 1-2 h, taking out, putting into a mildew chamber, standing for mildew for 1-2 weeks, transferring the mildewed flax fibers into a fermentation tank, adding water with the same mass as the mildewed flax fibers into the fermentation tank, uniformly stirring, sealing the opening of the tank, and standing for fermentation at 35-45 ℃ for 3-5 days;

(2) After the fermentation is finished, filtering and separating to obtain fermentation filter residues, putting the fermentation filter residues into a carbonization furnace, carbonizing at 200-300 ℃ for 1-2 hours to obtain a self-made porous carbon material, and mixing the self-made porous carbon material with a nickel nitrate solution with the mass fraction of 30% to obtain a mixed solution;

(3) And (3) moving the mixed solution into an ultrasonic oscillator, carrying out ultrasonic oscillation dipping and mixing for 1-2 hours at the frequency of 40-50 kHz, filtering after the ultrasonic oscillation dipping, separating to obtain dipping filter residues, putting the dipping filter residues into a sintering furnace, carrying out sintering treatment under the protection of nitrogen, and obtaining the self-made conductive filler after sintering.

In the specific preparation steps of the composite conductive hydrogel, by weight, 100-120 parts of hydrogel prepolymer, 60-70 parts of acrylamide, 1-2 parts of ammonium persulfate, 30-40 parts of N, N-methylene bisacrylamide and 3-5 parts of tetramethylethylenediamine are used.

in the preparation step (1) of the hydrogel prepolymer, the mass ratio of a polyvinyl alcohol solution with the mass fraction of 10% to a 3, 4-dihydroxybenzoic acid solution with the mass fraction of 30% is 5: 1.

In the step (2) of preparing the hydrogel prepolymer, the mass ratio of the self-made conductive filler to the reaction liquid is 1:10, and the addition amount of the catechol oxidase is 5% of the mass of the reaction liquid.

In the step (1) of preparing the self-made conductive filler, the temperature of a mildew room is 40-50 ℃, and the relative humidity of air is 70-80%.

in the step (2) of preparing the self-made conductive filler, the mass ratio of the self-made porous carbon material to the nickel nitrate solution with the mass fraction of 30% is 1: 5.

in the step (3) of preparing the self-made conductive filler, the sintering treatment temperature is 400-500 ℃ under the protection of nitrogen, and the sintering treatment time is 4-6 h.

The beneficial technical effects of the invention are as follows:

(1) Firstly, using flax fiber as raw material, soaking the flax fiber in methane liquid, standing still for mildewing and fermentation treatment, carbonizing fermentation filter residue, impregnating the carbonized fermentation filter residue with metal salt solution, sintering at high temperature to obtain self-made conductive filler, then mixing polyvinyl alcohol and 3, 4-dihydroxy benzoic acid, stirring for reaction to obtain reaction liquid, mixing the reaction liquid and the self-made conductive filler, adding catechol oxidase for prepolymerization reaction to obtain hydrogel prepolymer, finally mixing the hydrogel prepolymer with acrylamide, initiator and the like for reaction to finally obtain composite conductive hydrogel, firstly soaking the flax fiber in methane liquid rich in microorganisms, placing the soaked flax fiber in high-temperature and high-humidity environment to allow the microorganisms to breed mildews, then sealing and fermenting to utilize the microorganisms to carry out micro-corrosion on the surface of the flax fiber to generate a large number of uniform pores, carbonizing the fermented filter residue to obtain a porous carbon material, then soaking the porous carbon material in a nickel nitrate solution under the action of ultrasound to ensure that the metal salt is soaked in pores of the porous carbon material, then sintering, during sintering, a layer of carbon nanometer conduction band network is generated between the interface of the metal nickel and the porous carbon due to the catalytic action of the metal nickel, and in general, the carbon material is used as the conductive filler and has a relationship with the structure of the carbon material, the conductivity of the carbon material with a graphite structure is higher than that of an amorphous carbon structure, the formed carbon nanometer conduction band network is in a graphite structure, the electric conductivity of the composite material is increased, the thickness of the interface layer is increased along with the increase of the calcining temperature, and the conductive liquid is better, so that the carbon material with better conductivity is prepared, and the carbon material can be used as a filler to enhance the conductivity of the conductive hydrogel;

(2) The invention uses self-made conductive filler to react with reaction liquid generated by polyvinyl alcohol and 3, 4-dihydroxy benzoic acid, wherein polyvinyl alcohol solution and 3, 4-dihydroxy benzoic acid solution are firstly esterified to introduce catechol functional group, then the esterification reaction is carried out with catechol oxidase to oxidize the catechol group by the catechol oxidase to form a catechol structure, Michael addition reaction is carried out between the catechol to form covalent bond crosslinking points, finally a layer of hydrogel prepolymer is formed on the surface of the self-made conductive filler, and finally the prepolymer is compounded in situ in an elastic network formed by polyacrylamide to form the composite conductive hydrogel, because the hydrogel prepolymer and the polyacrylamide network are compounded in situ, the compatibility of the hydrogel prepolymer and the polyacrylamide is excellent, and the common conductive hydrogel is prevented from lacking interaction force between the conductive filler and the hydrogel matrix, the self-made conductive filler of the invention provides a nano-space limited oxidation environment for the oxidation polymerization of the hydrogel prepolymer, thereby preventing the over-oxidation of catechol groups, reserving a large amount of phenolic hydroxyl groups in the formed hydrogel prepolymer, and because the hydrogel prepolymer introduces a large amount of phenolic hydroxyl groups in a polyacrylamide network, the composite conductive hydrogel has good biocompatibility, and in the polymerization process of the hydrogel prepolymer, a physical anchoring effect is formed between the conductive filler and the hydrogel, and the conductive filler also increases the mechanical property of the hydrogel, and finally the composite conductive hydrogel prepared by the invention has excellent conductivity and mechanical property and excellent biocompatibility, has wide application prospect.

Detailed Description

soaking flax fibers in biogas liquid for 1-2 h, taking out, putting the flax fibers in a mildew chamber with the temperature of 40-50 ℃ and the relative air humidity of 70-80%, standing for 1-2 weeks, transferring the mildewed flax fibers into a fermentation tank, adding water with the quality of the mildewed flax fibers and the like into the fermentation tank, uniformly stirring, sealing the tank opening, and standing and fermenting at 35-45 ℃ for 3-5 days; after the fermentation is finished, filtering and separating to obtain fermentation filter residues, putting the fermentation filter residues into a carbonization furnace, carbonizing at 200-300 ℃ for 1-2 hours to obtain a self-made porous carbon material, and mixing the self-made porous carbon material and a nickel nitrate solution with the mass fraction of 30% according to the mass ratio of 1:5 to obtain a mixed solution; transferring the mixed solution into an ultrasonic oscillator, carrying out ultrasonic oscillation dipping and mixing for 1-2 h at the frequency of 40-50 kHz, filtering after the ultrasonic oscillation dipping, separating to obtain dipped filter residues, putting the dipped filter residues into a sintering furnace, heating to 400-500 ℃ under the protection of nitrogen, carrying out sintering treatment for 4-6 h, and obtaining a self-made conductive filler for later use after sintering; mixing a polyvinyl alcohol solution with the mass fraction of 10% and a 3, 4-dihydroxybenzoic acid solution with the mass fraction of 30% according to the mass ratio of 5:1, then putting the mixture into a reaction kettle, heating to 70-80 ℃, and stirring for reaction for 3-5 hours to obtain a reaction solution; mixing the prepared self-made conductive filler with the reaction liquid according to the mass ratio of 1:10, putting the mixture into a reaction kettle, continuously adding catechol oxidase with the mass of 5% of the reaction liquid into the reaction kettle, and stirring and reacting at the temperature of 30-40 ℃ and the rotating speed of 700-800 r/min for 4-6 hours to obtain a hydrogel prepolymer; weighing 100-120 parts of the hydrogel prepolymer, 60-70 parts of acrylamide, 1-2 parts of ammonium persulfate, 30-40 parts of N, N-methylene bisacrylamide and 3-5 parts of tetramethylethylenediamine, mixing, putting into a beaker, and stirring in an ice water bath for reaction for 10-15 min to obtain the composite conductive hydrogel.