A conductive hydrogel and its preparation method

Abstract

The present invention discloses a conductive hydrogel with high mechanical properties and electrical properties and a preparation method thereof. Aiming at the problems of poor mechanical properties and electrical properties of traditional conductive hydrogels, a hyperbranched polyaniline graphene composite is formed by in-situ polymerization of a hyperbranched polysiloxane prepolymer, aniline, and graphene oxide, and then a composite conductive hydrogel is prepared from the composite and acrylamide, which can be practically applied in the fields of sensors, capacitors, fluid control, intelligent machinery, etc.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of polymer materials, and particularly relates to a conductive hydrogel and a preparation method thereof. Background Art

[0002] Hydrogel is a superabsorbent polymer composed of lightly cross-linked poly(N-isopropylacrylamide), polyacrylamide, polyacrylic acid (salt), etc. and containing strong water-absorbing groups, and has a three-dimensional network structure. Hydrogel can absorb hundreds to thousands of times the liquid of its own weight, and the absorbed liquid does not release or releases very little under pressure, and has excellent gel stability, and can be used as a good carrier for functional soft materials.

[0003] In recent years, as a member of the intelligent hydrogel family, conductive hydrogel has gradually come into people's view. At first, the research focus of conductive hydrogel was on polyelectrolyte conductive hydrogel. However, due to the poor conductivity and mechanical strength of single-component conductive hydrogel, it could not meet the requirements. Then the research focus gradually shifted to conductive polymer-based conductive hydrogel and inorganic substance-added conductive hydrogel with better conductivity, stronger stability and better mechanical strength. Conductive polymer-based conductive hydrogel is composed of a mixture of polymers or two components of conductive polymer and hydrogel. The conductive polymers are polyaniline, polypyrrole, polythiophene, etc. Therefore, conductive polymer-based conductive hydrogel has the unique properties of two components. Both the conductive polymer and the hydrogel components belong to intelligent materials. Through copolymerization, cross-linking or grafting functional groups, the conductive polymer-based conductive hydrogel can meet the requirements of biology or molecular engineering. Inorganic substance-added conductive hydrogel is prepared with inorganic substance fillers such as graphite, carbon fiber, carbon nanotube, metal particles, etc. to prepare conductive hydrogel. The preparation process is simple and can be applied to supercapacitors, dye-sensitized solar cells, fuel cells, lithium rechargeable batteries, etc. At present, there are relevant researches on both polymer-based conductive hydrogel and inorganic conductive hydrogel, but the research focus is on mechanical properties or electrical properties. There is still a certain challenge in the research of hydrogel that improves both its mechanical properties and electrical properties. Summary of the Invention

[0004] The object of the present invention is to provide a conductive hydrogel with high mechanical properties and electrical properties and a preparation method thereof. Aiming at the problems of poor mechanical properties and electrical properties of traditional conductive hydrogel, a hyperbranched polyaniline graphene composite is formed by in-situ polymerization of hyperbranched polysiloxane prepolymer, aniline and graphene oxide, and then a composite conductive hydrogel is prepared by mixing it with acrylamide, which can be actually applied in the fields of sensors, capacitors, fluid control, intelligent machinery, etc.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A preparation method of a conductive hydrogel, comprising the following steps:

[0007] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 30 - 60 °C and continue the reaction. After 4 - 6 h, the reaction ends, and the polysiloxane prepolymer is obtained by rotary evaporation, controlling the molar ratio of water to siloxane to be 1.1 - 1.5∶1;

[0008] (2) Preparation of hyperbranched polyaniline graphene composite: Add aniline, graphene oxide, the polysiloxane prepolymer prepared in step (1), and an initiator into dimethyl sulfoxide. Under nitrogen protection and at 30 - 60 °C, mechanically stir, let stand and react for 12 - 24 h. After the reaction ends, remove the solvent, then wash, filter, and dry the reaction product to obtain the hyperbranched polyaniline graphene composite, where the mass ratio of aniline, graphene oxide, and polysiloxane prepolymer added is 1 - 10∶1 - 10∶0.1 - 1;

[0009] (3) Preparation of composite conductive hydrogel: Add the hyperbranched polyaniline graphene composite, water, a crosslinking agent, an initiator, and an accelerator prepared in step (2) into acrylamide. After ultrasonic stirring evenly, pour it into a mold and form a film at room temperature, where the mass ratio of acrylamide, hyperbranched polyaniline graphene composite, and water added is 1 - 5∶0.01 - 0.1∶10 - 20.

[0010] Further, in step (1), the reaction temperature is 50 °C and the reaction time is 5 h.

[0011] Further, in step (2), the initiator is ammonium persulfate, and the dosage is 1 - 3 wt% of the total dosage of aniline, graphene oxide, and polysiloxane prepolymer.

[0012] Further, in step (2), the mechanical stirring time is 20 - 50 min.

[0013] Further, in step (2), the drying step is vacuum drying at 50 °C for 24 hours.

[0014] Further, in step (3), the initiator is ammonium persulfate, and the dosage is 1 - 3 wt% of the acrylamide dosage.

[0015] Further, in step (3), the type of the accelerator is tetramethylethylenediamine.

[0016] Further, in step (3), the type of the crosslinking agent is N,N'-methylenebisacrylamide.

[0017] Further, in step (3), the dosage of the crosslinking agent is 0.1 - 3 wt% of the acrylamide dosage.

[0018] A conductive hydrogel is prepared by the above preparation method.

[0019] The remarkable advantages of the present invention are as follows:

[0020] (1) The hyperbranched polysiloxane prepared in the present invention contains terminal double bonds and can be covalently connected to aniline; the surface of graphene oxide contains abundant surface active groups such as carboxyl groups and hydroxyl groups, which can be connected to aniline and hyperbranched polysiloxane; aniline, graphene oxide, and polysiloxane prepolymer react to form an overall conductive network, while improving the mechanical properties and conductive properties of the hydrogel.

[0021] (2) The hyperbranched polyaniline graphene composite prepared in the present invention has stable performance, small dosage, is evenly distributed in the acrylamide hydrogel, significantly improves the mechanical properties and conductive properties of the conductive hydrogel, the mechanical property reaches about 0.7 MPa, and the electrical property reaches about 1×10 -2 S / cm. Specific embodiments

[0022] In order to more clearly understand the above technical route and beneficial effects of the present invention, the technical solution of the present invention will be further described below in conjunction with specific embodiments. The tensile property is tested on a universal tensile machine, and the conductive property is tested using a conductivity meter.

[0023] Example 1

[0024] A preparation method of an amphoteric ion organic gel electrolyte includes the following steps:

[0025] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 50 °C and continue the reaction. After 5 h of reaction, rotary evaporation is carried out to obtain a polysiloxane prepolymer, and the molar ratio of water to siloxane is controlled to be 1.5∶1;

[0026] (2) Preparation of hyperbranched polyaniline graphene composite: Add 1 g of aniline, 1 g of graphene oxide, 0.2 g of polysiloxane prepolymer, and 0.05 g of ammonium persulfate to 90 mL of dimethyl sulfoxide, mechanically stir for 30 min under nitrogen protection at 50 °C, and let it stand for reaction for 12 h. After the reaction is completed, the solvent is removed, and then the reaction product is washed, filtered by suction, and vacuum dried at 5 °C for 24 hours to obtain a hyperbranched polyaniline graphene composite;

[0027] (3) Preparation of composite conductive hydrogel: Add 2 g of acrylamide, 0.02 g of hyperbranched polyaniline graphene composite, 20 mL of water, 0.01 g of N,N-methylenebisacrylamide, 0.05 g of ammonium persulfate, and then add 20 μL of accelerator tetramethylethylenediamine. After ultrasonic stirring evenly, pour it into a mold and form a film at room temperature.

[0028] After testing, the tensile property of the conductive hydrogel prepared in Example 1 is 0.72 MPa, and the conductivity is 1.07×10 -2 S / cm.

[0029] Example 2

[0030] A preparation method of an amphoteric ion organic gel electrolyte, comprising the following steps:

[0031] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 40 °C and continue the reaction. After 6 h of reaction, rotary evaporation is carried out to obtain the polysiloxane prepolymer, and the molar ratio of water to siloxane is controlled to be 1.5∶1;

[0032] (2) Preparation of hyperbranched polyaniline graphene composite: Add 1 g of aniline, 1 g of graphene oxide, 0.15 g of polysiloxane prepolymer, and 0.05 g of ammonium persulfate to 90 mL of dimethyl sulfoxide. Under nitrogen protection and at 50 °C, mechanically stir for 30 min, and then let it stand for reaction for 12 h. After the reaction is completed, the solvent is removed, and then the reaction product is washed, filtered by suction, and vacuum-dried at 5 °C for 24 hours to obtain the hyperbranched polyaniline graphene composite;

[0033] (3) Preparation of composite conductive hydrogel: Add 2 g of acrylamide, 0.015 g of hyperbranched polyaniline graphene composite, 20 mL of water, 0.01 g of N,N'-methylenebisacrylamide, and 0.05 g of ammonium persulfate. Then add 20 μL of accelerator tetramethylethylenediamine, stir evenly by ultrasonic wave and pour it into a mold to form a film at room temperature.

[0034] After testing, the tensile property of the conductive hydrogel prepared in Example 2 is 0.70 MPa, and the conductivity is 0.95×10 -2 S / cm.

[0035] Example 3

[0036] A preparation method of an amphoteric ion organic gel electrolyte, comprising the following steps:

[0037] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 60 °C and continue the reaction. After 4 h of reaction, rotary evaporation is carried out to obtain the polysiloxane prepolymer, and the molar ratio of water to siloxane is controlled to be 1.5∶1;

[0038] (2) Preparation of hyperbranched polyaniline graphene composite: 1 g of aniline, 1 g of graphene oxide, 0.25 g of polysiloxane prepolymer, and 0.05 g of ammonium persulfate were added to 90 mL of dimethyl sulfoxide. Under nitrogen protection and at 50 °C, mechanical stirring was carried out for 30 min, and then the mixture was allowed to stand and react for 12 h. After the reaction, the solvent was removed, and then the reaction product was washed, filtered by suction, and vacuum-dried at 5 °C for 24 h to obtain the hyperbranched polyaniline graphene composite;

[0039] (3) Preparation of composite conductive hydrogel: 2 g of acrylamide was added with 0.025 g of hyperbranched polyaniline graphene composite, 20 mL of water, 0.01 g of N,N'-methylenebisacrylamide, and 0.05 g of ammonium persulfate. Then, 20 μL of accelerator tetramethylethylenediamine was added. After ultrasonic stirring evenly, the mixture was poured into a mold and formed a film at room temperature.

[0040] After testing, the tensile property of the conductive hydrogel prepared in Example 1 was 0.74 MPa, and the conductivity was 1.14×10 -2 S / cm.

[0041] Example 4

[0042] A preparation method of an amphoteric ionic organic gel electrolyte includes the following steps:

[0043] (1) Preparation of hyperbranched polysiloxane prepolymer: γ-methacryloxypropyltrimethylsiloxane was taken, and dilute hydrochloric acid was added under stirring at room temperature. The temperature was raised to 50 °C and the reaction continued for 5 h. After the reaction ended, the polysiloxane prepolymer was obtained by rotary evaporation, and the molar ratio of water to siloxane was controlled to be 1.4∶1;

[0044] (2) Preparation of hyperbranched polyaniline graphene composite: 0.9 g of aniline, 1.1 g of graphene oxide, 0.15 g of polysiloxane prepolymer, and 0.05 g of ammonium persulfate were added to 90 mL of dimethyl sulfoxide. Under nitrogen protection and at 50 °C, mechanical stirring was carried out for 30 min, and then the mixture was allowed to stand and react for 12 h. After the reaction, the solvent was removed, and then the reaction product was washed, filtered by suction, and vacuum-dried at 5 °C for 24 h to obtain the hyperbranched polyaniline graphene composite;

[0045] (3) Preparation of composite conductive hydrogel: 2 g of acrylamide was added with 0.015 g of hyperbranched polyaniline graphene composite, 20 mL of water, 0.01 g of N,N'-methylenebisacrylamide, and 0.05 g of ammonium persulfate. Then, 20 μL of accelerator tetramethylethylenediamine was added. After ultrasonic stirring evenly, the mixture was poured into a mold and formed a film at room temperature.

[0046] After testing, the tensile property of the conductive hydrogel prepared in Example 4 was 0.71 MPa, and the conductivity was 0.97×10 -2 S / cm.

[0047] Example 5

[0048] A preparation method of an amphoteric ionic organic gel electrolyte, comprising the following steps:

[0049] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 50 °C and continue the reaction. After 5 h of reaction, rotary evaporation is carried out to obtain the polysiloxane prepolymer, and the molar ratio of water to siloxane is controlled to be 1.3:1;

[0050] (2) Preparation of hyperbranched polyaniline graphene composite: Add 1.1 g of aniline, 0.9 g of graphene oxide, 0.25 g of polysiloxane prepolymer, and 0.05 g of ammonium persulfate to 90 mL of dimethyl sulfoxide. Under nitrogen protection and at 50 °C, mechanically stir for 30 min and allow to stand for reaction for 12 h. After the reaction is completed, the solvent is removed, and then the reaction product is washed, filtered by suction, and vacuum dried at 5 °C for 24 h to obtain the hyperbranched polyaniline graphene composite;

[0051] (3) Preparation of composite conductive hydrogel: Add 2 g of acrylamide, 0.025 g of hyperbranched polyaniline graphene composite, 20 mL of water, 0.01 g of N,N'-methylenebisacrylamide, and 0.05 g of ammonium persulfate, and then add 20 μL of accelerator tetramethylethylenediamine. After ultrasonic stirring evenly, pour it into a mold and form a film at room temperature.

[0052] After testing, the tensile property of the conductive hydrogel prepared in Example 1 is 0.73 MPa, and the conductivity is 1.12×10 -2 S / cm.

[0053] Comparative Example 1

[0054] This comparative example has the same feeding order and preparation steps as Example 1, the difference is that graphene oxide is not added when preparing hyperbranched polyaniline, and the same mass of graphene oxide is added in step (3). The specific steps are as follows:

[0055] A preparation method of an amphoteric ionic organic gel electrolyte, comprising the following steps:

[0056] (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 50 °C and continue the reaction. After 5 h of reaction, rotary evaporation is carried out to obtain the polysiloxane prepolymer, and the molar ratio of water to siloxane is controlled to be 1.5:1;

[0057] (2) Preparation of hyperbranched polyaniline graphene composite: 1 g of aniline, 0.2 g of polysiloxane prepolymer, and 0.05 g of ammonium persulfate were added to 90 mL of dimethyl sulfoxide. Under nitrogen protection and at 50 °C, mechanical stirring was carried out for 30 min, and then the mixture was allowed to stand and react for 12 h. After the reaction, the solvent was removed, and then the reaction product was washed, filtered by suction, and vacuum-dried at 5 °C for 24 h to obtain the hyperbranched polyaniline composite;

[0058] (3) Preparation of composite conductive hydrogel: 2 g of acrylamide was added with 0.02 g of hyperbranched polyaniline graphene composite, 0.009 g of graphene oxide, 20 mL of water, 0.01 g of N,N'-methylenebisacrylamide, and 0.05 g of ammonium persulfate. Then, 20 μL of accelerator tetramethylethylenediamine was added. After ultrasonic stirring evenly, the mixture was poured into a mold and formed into a film at room temperature.

[0059] After testing, the tensile property of the conductive hydrogel prepared in Comparative Example 1 was 0.56 MPa, and the conductivity was 0.78×10 -2 S / cm.

[0060] Comparative Example 2

[0061] This comparative example has the same feeding sequence and preparation steps as Example 1, except that the polysiloxane prepolymer was removed from the raw materials. To ensure the same mass of polymer monomers, the addition amounts of aniline and graphene oxide were increased to 1.1 g. The specific steps are as follows:

[0062] A preparation method of an amphoteric ionic organic gel electrolyte includes the following steps:

[0063] (1) Preparation of hyperbranched polyaniline graphene composite: 1.1 g of aniline, 1.1 g of graphene oxide, and 0.05 g of ammonium persulfate were added to 90 mL of dimethyl sulfoxide. Under nitrogen protection and at 50 °C, mechanical stirring was carried out for 30 min, and then the mixture was allowed to stand and react for 12 h. After the reaction, the solvent was removed, and then the reaction product was washed, filtered by suction, and vacuum-dried at 5 °C for 24 h to obtain the polyaniline graphene composite;

[0064] (2) Preparation of composite conductive hydrogel: 2 g of acrylamide was added with 0.02 g of hyperbranched polyaniline graphene composite, 20 mL of water, 0.01 g of N,N'-methylenebisacrylamide, and 0.05 g of ammonium persulfate. Then, 20 μL of accelerator tetramethylethylenediamine was added. After ultrasonic stirring evenly, the mixture was poured into a mold and formed into a film at room temperature.

[0065] After testing, the tensile property of the conductive hydrogel prepared in Comparative Example 2 was 0.48 MPa, and the conductivity was 0.85×10 -2 S / cm.

[0066] As can be seen from Comparative Example 1, the addition timing of graphene oxide is very important. Through the reaction with aniline and hyperbranched polysiloxane prepolymer, an overall conductive network formed by the three can be obtained, while improving the mechanical properties and conductive properties of the hydrogel. If graphene oxide is added subsequently, both the mechanical properties and conductive properties will decrease. As can be seen from Comparative Example 2, the hyperbranched polysiloxane prepolymer can endow the hyperbranched polyaniline-graphene composite with more excellent crosslinking and conductive effects, thereby improving the mechanical properties and conductive properties of the hydrogel.

[0067] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A preparation method of a conductive hydrogel, characterized in that, It includes the following steps: (1) Preparation of hyperbranched polysiloxane prepolymer: Take γ-methacryloxypropyltrimethylsiloxane, add dilute hydrochloric acid under stirring at room temperature, raise the temperature to 30 - 60 °C and continue the reaction. After 4 - 6 h, the reaction ends. Rotary evaporation is carried out to obtain the polysiloxane prepolymer, and the molar ratio of water to siloxane is controlled to be 1.1 - 1.5:1; (2) Preparation of hyperbranched polyaniline graphene composite: Add aniline, graphene oxide, the polysiloxane prepolymer prepared in step (1), and an initiator into dimethyl sulfoxide. Under nitrogen protection and at 30 - 60 °C, mechanically stir, let it stand and react for 12 - 24 h. After the reaction ends, remove the solvent, then wash, filter by suction, and dry the reaction product to obtain the hyperbranched polyaniline graphene composite, where the mass ratio of aniline, graphene oxide, and polysiloxane prepolymer added is 1 - 10:1 - 10:0.1 - 1, and the dosage of the initiator is 1 - 3 wt% of the total dosage of aniline, graphene oxide, and polysiloxane prepolymer; (3) Preparation of composite conductive hydrogel: Add the hyperbranched polyaniline graphene composite prepared in step (2), water, a crosslinking agent, an initiator, and an accelerator into acrylamide. After ultrasonic stirring evenly, pour it into a mold and form a film at room temperature, where the mass ratio of acrylamide, hyperbranched polyaniline graphene composite, and water added is 1 - 5:0.01 - 0.1:10 - 20.

2. The preparation method of the conductive hydrogel according to claim 1, characterized in that: In step (1), the reaction temperature is 50 °C and the reaction time is 5 h.

3. The preparation method of the conductive hydrogel according to claim 1, wherein: In step (2), the initiator is ammonium persulfate.

4. The preparation method of the conductive hydrogel according to claim 1, wherein: In step (2), the mechanical stirring time is 20 - 50 min.

5. The preparation method of the conductive hydrogel according to claim 1, characterized in that: In step (2), the drying step is vacuum drying at 50 °C for 24 hours.

6. The preparation method of the conductive hydrogel according to claim 1, wherein: In step (3), the initiator is ammonium persulfate, and the dosage is 1 - 3 wt% of the acrylamide dosage.

7. The preparation method of the conductive hydrogel according to claim 1, characterized in that: In step (3), the type of the accelerator is tetramethylethylenediamine.

8. The preparation method of the conductive hydrogel according to claim 1, characterized in that: In step (3), the type of the crosslinking agent is N,N'-methylenebisacrylamide.

9. The preparation method of the conductive hydrogel according to claim 1, characterized in that: In step (3), the dosage of the crosslinking agent is 0.1 - 3 wt% of the acrylamide dosage.

10. A conductive hydrogel prepared by the preparation method according to any one of claims 1 - ⑨.