CN107698914A - A kind of preparation method of flexible memory conductive polymer composite aquogel - Google Patents

Abstract

The invention discloses a preparation method of a flexible memory polymer conductive composite hydrogel, which comprises the following steps: (1) dissolving pyrrole monomer in graphene oxide aqueous solution, stirring and dispersing by ultrasonic wave to form a solution, which is ready for use; (2) ) Add ferrous salt and H ₂ O ₂ solution to the solution obtained in step (1) sequentially, stir and disperse with ultrasonic waves to form a reaction system; (3) React the above reaction system at 0 to 20°C for 2 hours under stirring conditions; (4 ) Add initiator and N,N'-methylenebisacrylamide to the reactant obtained in step (3), stir and ultrasonically disperse evenly, then add acrylic acid, continue stirring for 5-10min; (5) Stand in an oven at 70°C For the reaction, place the obtained hydrogel in hydriodic acid with a mass fraction of 45% for reduction, and then purify and balance the obtained product in distilled water to obtain a flexible memory polymer conductive composite hydrogel.

Description

Preparation method of flexible memory polymer conductive composite hydrogel

technical field

The invention belongs to the technical field of supercapacitor electrode materials, and in particular relates to a preparation method of a flexible memory polymer conductive composite hydrogel.

Background technique.

With the rapid development of flexible electronics science and miniaturization technology of electronic products, flexible, wearable, foldable and portable electronic devices have come out one after another. As a kind of flexible power supply, due to its excellent electrochemical properties such as fast charge and discharge, high power density, and long cycle life, as well as mechanical deformation properties such as stretchable, bendable, and foldable, flexible supercapacitors meet the needs of wearable and portable Energy requirements of electronic devices. As the main component of supercapacitor, electrode material directly affects its performance. Electrode materials commonly used in supercapacitors, carbon materials, transition metal oxides and conductive polymers have limited flexibility, and their stretching and bending limits are very small, which is difficult to meet the requirements of flexible supercapacitors, usually by means of non-conductive flexible substrates. Composite materials as electrodes for flexible supercapacitors.

Hydrogels are a special class of wet and soft materials. It is a three-dimensional network polymer containing a large number of hydroxyl groups, amino groups and carboxyl groups and moderately cross-linked. It can swell in water and maintain a certain shape before and after water absorption. It has excellent elasticity and stretchability. Release, chemical sensors, artificial muscles and other fields have attractive application prospects. In recent years, polymer hydrogels have been applied in supercapacitors, with flexible and stretchable polymer-based hydrogels, such as oxidized polyethylene-based hydrogels, polyacrylic acid-based hydrogels, and polyvinyl alcohol-based hydrogels. , mainly used as supercapacitor electrolyte. Tang et al. immersed the cross-linked polyacrylic acid hydrogel in the aniline monomer, and then initiated the polymerization after the aniline permeated in the polyacrylic acid. The obtained polyaniline/polyacrylic acid 3D interpenetrating network polymer has good conductivity and can be used as an electrolyte for supercapacitors (Tang ZY, Wu J H, Liu Q, Zheng M, Tang QW, Lan Z, Lin JM. Preparation of poly (acrylic acid)/gelatin/polyaniline gel-electrolyte and its application in quasi-solid-state dye-sensitized solar cells. J. Power Sources, 2012, 203:282-287.).

Flexible hydrogel electrodes prepared by compounding conductive polymers and polymer hydrogels can obtain good electrochemical activity. For example, Li et al. introduced conductive polyaniline into the three-dimensional network framework of polyvinyl alcohol to prepare high-strength supramolecular hydrogels, which can be used as electrode materials for flexible supercapacitors to obtain good electrochemical activity (Li WW, Gao FX, WangXQ, Zhang N, Ma MM. Strong and robust polyaniline-based supramolecularhydrogels for flexible supercapacitors. Angew. Chem. Int. Ed., 2016, 55: 1-8.). Hao et al placed the conductive polymer monomer in the cross-linked polyacrylamide hydrogel, and adopted a "two-step method" to prepare the polyacrylamide hydrogel first, and then soak it in the aniline monomer solution to prepare Flexible and stretchable polyacrylamide/conductive polyaniline hydrogel electrodes, the introduction of α-cyclodextrin with amphiphilic structure induces the polymerization of aniline inside the hydrogel 3D porous structure, and its superior supercapacitive properties are attributed to the flexible Polymer chains, highly connected porous structure and good contact between matrix and conductive polyaniline (Hao GP, Hippauf F, Oschatz M, Wisser FM, Leifert A, Nicel W, Mohamed-Noriega N, Zheng ZK, Kaskel S . Stretchable and semitransparentconductive hybrid hydrogels for flexible supercapacitors. ACS Nano, 2014, 7:7138-7146.). In summary, flexible and stretchable conductive composite hydrogel electrodes have a certain basis, but the current conductive and mechanical properties (stretching, flexible bending properties) of flexible electrode materials cannot meet the needs of future portable electronic products.

Contents of the invention

In order to solve the above problems, the object of the present invention is to introduce graphene with high electrochemical activity and high conductivity, and conductive polymers into the three-dimensional network structure of flexible polyacrylic acid hydrogel. On the one hand, the introduction of graphene can form an appropriate amount of conductive cross-linking points, thereby further regulating the mechanical and electrochemical properties of the flexible composite hydrogel; on the other hand, the electric double layer capacitance and the Faraday capacitance provided by the electroactive material The combination can increase the overall specific capacitance of the electrode material, thereby further increasing its energy density. This method has not been reported at home and abroad.

In order to realize the foregoing invention object, the technical scheme that the present invention adopts is as follows:

A method for preparing a flexible memory polymer conductive composite hydrogel, comprising the steps of:

(1) Dissolve the pyrrole monomer in the graphene oxide aqueous solution, stir and disperse with ultrasonic waves to form a solution, and set aside, the concentration of graphene oxide is 0.1-2mg/mL, and the concentration of pyrrole monomer is 0.01M-0.3M;

(2) Add ferrous salt and H ₂ O ₂ solution to the solution obtained in step (1) sequentially, stir and disperse with ultrasonic waves to form a reaction system; the ferrous salt is one of ferrous sulfate and ferrous chloride , the mol ratio of H ₂ O ₂ and pyrrole is 20:1-2:1, and the mol ratio of H ₂ O ₂ and ferrous salt is 1000:1-100:1;

(3) React the reaction system obtained in step (2) for 2 hours under stirring at 0-20°C;

(4) Add initiator and N,N′-methylenebisacrylamide to the reactant obtained in step (3), stir and ultrasonically disperse evenly, add acrylic acid, and continue stirring for 5-10min; the initiator is persulfuric acid One of ammonium and azobisisobutylamidine hydrochloride, the concentration of acrylic acid is 5-20mg/mL, the mass ratio of ammonium persulfate to acrylic acid is 10:1-100:1, acrylic acid and N, Nˊ- The mass ratio of methylenebisacrylamide is 200:1-50:1,

(5) Stand the reaction in an oven at 70°C for 6-24 hours, place the obtained hydrogel in hydriodic acid with a mass fraction of 45% for reduction, and then purify and balance the obtained product in distilled water for 12-24 hours, The water was changed every 6 hours to obtain the flexible memory polymer conductive composite hydrogel.

The present invention adopts the H ₂ O ₂ -Fe ²⁺ system, the molar ratio of hydrogen peroxide to ferrous salt is 1000:1-100:1, the hydrogen peroxide is too much, the use of H ₂ O ₂ alone cannot make pyrrole polymerize, Fe ²⁺ here acts as a catalyst to promote the oxidation of _pyrrole by _H2O2 . When H ₂ O ₂ is added, it reacts preferentially with FeCl ₂ , transforming Fe ²⁺ into Fe ³⁺ and generating •OH. During the whole process of polymerization, Fe ³⁺ can slowly oxidize pyrrole to form pyrrole polymer. Fe ³⁺ is reduced to Fe ²⁺ while oxidizing polypyrrole, and Fe ²⁺ reacts with H ₂ O ₂ to form Fe ³⁺ and ·OH. This cycle is repeated until H ₂ O ₂ is exhausted, and pyrrole Polymerized into polypyrrole. The polymerization rate of pyrrole is slow throughout the reaction process, and the obtained nano-polypyrrole can be well dispersed into the graphene oxide solution. At the same time, there are hydrogen bonds and p-π conjugation effects between the OH continuously produced in the reaction process, graphene oxide and polypyrrole, so that the generated polypyrrole can be stably dispersed in the graphene oxide solution, giving full play to its subsequent use. Electrochemical activity in the formed flexible hydrogel 3D network structure. The beneficial effects of the present invention are as follows:

1. The present invention utilizes the oxygen-containing functional groups on the surface of graphene oxide to give it good dispersibility in hydrogel, and after graphene oxide is reduced, graphene serves as a conductive physical cross-linking point to give composite hydrogel good mechanical properties; at the same time, Using a complex oxidant system to regulate the stable and uniform dispersion of conductive polypyrrole molecular chains in the 3D crosslinked network structure, endowing the composite hydrogel with good electrochemical activity, has not been reported in domestic and foreign literature.

2. The conductive composite hydrogel prepared by the present invention has good flexibility, bending and tensile properties. After drying the water in it, the volume shrinks and hardens, and after reabsorbing water, the volume increases and restores flexibility. Its 3D network structure Has a good memory effect.

3. The polymerization reaction of the present invention is carried out under normal temperature and static state, the equipment is simple, the operation is easy, and it is easy to expand large-scale production.

Description of drawings

Fig. 1 is the hydrogel stress-strain curve figure prepared by the present invention;

Fig. 2 is an SEM photo of the flexible recovery and porous structure change of the composite hydrogel prepared in the present invention.

detailed description

The present invention will be described in further detail below through specific examples.

Example 1

A method for preparing a flexible memory polymer conductive composite hydrogel, the steps are as follows:

(1) Dissolve 14 μL (0.2 mmol) of pyrrole monomer in 20 mL (0.1 mg/mL) of graphene oxide aqueous solution, stir and disperse with ultrasonic waves to form a solution;

(2) Add 0.5 mg of ferrous chloride (4×10 ^-6 mol) and 122 μL of 30% H ₂ O ₂ (4 mmol) solution to the solution obtained in the above step (1) sequentially, and disperse by ultrasonic waves;

(3) React the product obtained in step (2) for 2 hours under stirring at 0°C;

(4) Add 0.1g of ammonium persulfate and 5mg of N,N'-methylenebisacrylamide to the reactant obtained in step (3), stir and ultrasonically disperse evenly, add 1g of acrylic acid, and continue stirring for 10 minutes;

(5) Stand for reaction in an oven at 70°C for 6 hours, place the obtained hydrogel in hydriodic acid with a mass fraction of 45% for reduction, then purify and balance the obtained product in distilled water for 12 hours, and change it every 6 hours water to obtain flexible memory polymer conductive composite hydrogel.

Example 2

A method for preparing a flexible memory polymer conductive composite hydrogel, which is different from Example 1 in that 14 μL (0.2 mmol) of pyrrole monomer is changed to 420 μL (6 mmol), and the concentration of graphene oxide is changed from 0.1 mg/mL to 2mg/mL, 0.5mg ferrous chloride (4×10 ^-6 mol) becomes 0.0152g (1.2×10 ^-4 mol), 122μL 30%H ₂ O ₂ (4mmol) becomes 366μL 30%H ₂ O ₂ (12mmol), 0.1g ammonium persulfate becomes 0.04g ammonium persulfate, 5mg N, N'-methylenebisacrylamide becomes 0.08gN, N'-methylenebisacrylamide, and the quality of acrylic acid changes from 1g to 4g . The 0°C in step (3) was changed to 5°C, the static reaction in step (5) was changed from 6h to 24h, and the purification equilibrium time was changed from 12h to 24h.

Example 3

A method for preparing a flexible memory polymer conductive composite hydrogel, which is different from Example 1 in that 14 μL (0.2 mmol) of pyrrole monomer is changed to 70 μL (1 mmol), and the concentration of graphene oxide is changed from 0.1 mg/mL to 0.5mg/mL, 0.5mg ferrous chloride (4×10 ^-6 mol) becomes 2.4mg (1.88×10 ^-5 mol), 122μL 30%H ₂ O ₂ (4mmol) becomes 432μL 30%H ₂ O ₂ (15mmol), 0.1g ammonium persulfate becomes 0.08g azobisisobutylamidine hydrochloride, 5mg N, N′-methylenebisacrylamide becomes 0.0106gN, N′-methylenebisacrylamide , the quality of acrylic acid changed from 1g to 1.6g. The 0°C in step (3) was changed to 10°C, the standing reaction in step (5) was changed from 6h to 12h, and the purification equilibrium time was changed from 12h to 18h.

Example 4

A method for preparing a flexible memory polymer conductive composite hydrogel, which is different from Example 1 in that 14 μL (0.2 mmol) of pyrrole monomer is changed to 140 μL (2 mmol), and the concentration of graphene oxide is changed from 0.1 mg/mL to 1mg/mL, 0.5mg ferrous chloride (4×10 ^-6 mol) becomes 6.1mg (5×10 ^-5 mol), 122μL 30%H ₂ O ₂ (4mmol) becomes 613μL 30%H ₂ O ₂ (20mmol), 0.1g ammonium persulfate becomes 0.06g azobisisobutylamidine hydrochloride, 5mg N, N′-methylenebisacrylamide becomes 0.024gN, N′-methylenebisacrylamide, The quality of acrylic acid changed from 1g to 2.4g. The 0°C in step (3) was changed to 15°C, the standing reaction in step (5) was changed from 6h to 18h, and the purification equilibrium time was changed from 12h to 18h.

Example 5

A method for preparing a flexible memory polymer conductive composite hydrogel, which differs from Example 1 in that 14 μL (0.2 mmol) of pyrrole monomer is changed to 280 μL (4 mmol), and the concentration of graphene oxide is changed from 0.1 mg/mL to 1.5mg/mL, 0.5mg ferrous chloride (4×10 ^-6 mol) becomes 0.0102g (6.7×10 ^-5 mol) ferrous sulfate, 122μL 30%H ₂ O ₂ (4mmol) becomes 613μL 30 %H ₂ O ₂ (20mmol), 0.1g ammonium persulfate becomes 0.0375g ammonium persulfate, 5mg N,N′-methylenebisacrylamide becomes 0.0375gN,N′-methylenebisacrylamide, mass of acrylic acid From 1g to 3g. The 0°C in step (3) is changed to 20°C, the standing reaction in step (5) is changed from 6h to 24h, and the purification equilibrium time is changed from 12h to 24h

The performance parameters of the composite materials prepared in Examples 1-5 are shown in Table 1.

Table 1

Elongation was calculated according to the following formula:

Among them, δ is the elongation rate, L is the maximum elongation length, and s is the original length

Figure 1 is the stress-strain curve of the composite hydrogel prepared in Example 1 of the present invention. It can be seen from the curve that its elongation at break can reach 400%, and its tensile strength can reach 0.2MPa, showing good flexibility and stretchability performance.

Fig. 2 is an SEM photo of the flexibility recovery and porous structure change of the composite hydrogel prepared in Example 1 of the present invention. This kind of hydrogel shrinks after drying, and it will regain its flexibility when it is re-immersed in water (as shown in the upper right corner of Figure 2). amount to regulate the change of its porous structure.

The above embodiments have described the technical solutions of the present invention in detail. Obviously, the invention is not limited to the described embodiments. Based on the embodiments of the present invention, those skilled in the art can make various changes accordingly, but any changes that are equivalent or similar to the present invention fall within the protection scope of the present invention.

Claims (7)

1. a kind of preparation method of flexible memory conductive polymer composite aquogel, it is characterised in that comprise the following steps：

(1) pyrrole monomer is dissolved in graphene oxide water solution, stirs and form solution using ultrasonic wave is scattered, it is standby；

(2) by ferrous salt and H₂O₂Solution is sequentially added in step (1) resulting solution, is stirred and is formed instead using ultrasonic wave is scattered Answer system；

(3) reaction system obtained by step (2) is reacted into 2h under 0 to 20 DEG C of stirring condition；

(4) initiator and N, N ˊ-methylene-bisacrylamide are added in step (3) gained reactant, stirs simultaneously ultrasonic disperse Acrylic acid is added after uniformly, continues to stir 5-10min；

(5) reaction is stood in 70 DEG C of baking ovens, obtained hydrogel is placed in the hydroiodic acid that mass fraction is 45% and gone back After original, by obtained product in distilled water cleaning and balance, obtain flexible memory conductive polymer composite aquogel.

2. preparation method according to claim 1, it is characterised in that the concentration of graphene oxide is described in step (1) 0.1-2mg/mL, the concentration of the pyrrole monomer is 0.01M-0.3M.

3. preparation method according to claim 1, it is characterised in that the ferrous salt described in step (2) is ferrous sulfate Or frerrous chloride.

4. preparation method according to claim 1, it is characterised in that H described in step (2)₂O₂Mol ratio with pyrroles is 20:1-2:1, the H₂O₂Mol ratio with ferrous salt is 1000:1-100:1.

5. preparation method according to claim 1, it is characterised in that the initiator described in step (4) is ammonium persulfate Or azo diisobutyl amidine hydrochloride, the concentration of described acrylic acid is 5-20mg/mL, acrylic acid and N, N ˊ-di-2-ethylhexylphosphine oxide third The mass ratio of acrylamide is 200:1-50:1,

6. preparation method according to claim 1, it is characterised in that the initiator described in step (4) is ammonium persulfate, The mass ratio of ammonium persulfate and acrylic acid is 10:1-100:1.

7. preparation method according to claim 1, it is characterised in that the time that reaction is stood described in step (5) is 6- 24h, cleaning and balance time are 12-24h, and a water is changed per 6h.