CN113980296B - A kind of high tensile photocurable ion conductive hydrogel and preparation method thereof - Google Patents

Abstract

The invention discloses a high-stretch light-curing ion conductive hydrogel and a preparation method thereof, belonging to the technical field of polymer hydrogel materials. The invention utilizes a two-step method of photocuring and solvent replacement, and under specific conditions, introduces electrolyte ions into the photocurable hydrogel to obtain high stretchability, high transparency, high conductivity, good water retention capacity, and good strain. Sensitive and biocompatible ionically conductive hydrogels. Compared with the existing acrylic ion-conducting hydrogel prepared by light curing, its production is simpler and more efficient, and the raw materials are green, environmentally friendly, non-toxic and non-polluting. The hydrogel has good application prospects in human tissue engineering and flexible electronic devices, especially flexible pressure sensors.

Description

A kind of high tensile photocurable ion conductive hydrogel and preparation method thereof

technical field

The invention relates to a high-stretch light-curing ion conductive hydrogel and a preparation method thereof, belonging to the field of polymer hydrogels.

Background technique

The production and manufacture of traditional electronic products are mainly made of metal materials or semiconductor materials. These materials have greater rigidity, excellent electrical conductivity and good sensing sensitivity. With the development of science and technology, flexible electronic components with deformability, flexibility and ductility are becoming more and more important. As a new type of flexible electronic material, conductive hydrogel is due to its excellent flexibility and good conductivity. and tunable mechanical properties have received extensive attention. Traditional conductive hydrogels are composed of intrinsic conductive polymers and other hydrogel matrices. The rigidity of conductive polymers itself leads to defects in tensile properties. The ion-conducting hydrogel is composed of flexible polymer chains and conducts electricity by the electrolyte solution dispersed in it, so it can make up for the defects of stretchability and transparency of the intrinsically-conducting polymer hydrogel.

At present, most of the raw materials of photocurable ion-conducting hydrogels are polyacrylic acid, polyacrylamide, k-carrageenan and other polymer materials containing carboxylic acid and amide groups. In the process, it is inevitable to add photoinitiators with certain toxicity such as 2-hydroxyl-2-methyl-1-phenyl-1-acetone (photoinitiator 1173), 2-hydroxyl-4-(2-hydroxyl Ethoxy) ~ 2-methyl Propiophenone (photoinitiator 2959), this type of hydrogel has certain toxic and side effects, which will adversely affect people's health during daily use.

Therefore, the development and preparation of a non-acrylic, environmentally friendly, highly stretchable photocurable conductive hydrogel has become an urgent problem to be solved.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the first object of the present invention is to provide a high-stretch light-cured ionically conductive hydrogel and a preparation method thereof. The main steps are as follows,

(1) dilute the polyvinyl alcohol-styrene pyridinium salt solution with deionized water to obtain a pregel solution;

(2) The pregel solution is placed in a transparent glass mold, cross-linked in an ultraviolet curing machine to obtain a hydrogel, and the hydrogel is soaked in an electrolyte salt solution to fully replace the solvent to obtain a photocurable ionic conductivity Hydrogels.

Specifically, the degree of polymerization of the polyvinyl alcohol-styrene pyridinium salt is 1700.

Specifically, the mass fraction of the solute in the polyvinyl alcohol-styrene pyridinium salt solution is 10% to 15%.

Specifically, the electrolyte salt is one of ferric chloride, sodium chloride, calcium chloride, and aluminum chloride.

Specifically, the wavelength of the light source of the UV curing machine is 365 mm, and the intensity is 1600 mJ/cm ² .

Specifically, the ultraviolet curing temperature is room temperature, and the curing time is 6 minutes. The purpose is to make the styrene pyridinium salt (SbQ) group in the above solution undergo photodimerization to generate chemical cross-linking bonds to form a complete hydrogel.

Specifically, the concentration of the solute in the electrolyte salt solution is 0.1-0.6 mol/L.

Specifically, the temperature of the solvent replacement reaction is room temperature, and the time is 1 to 3 hours. The purpose is to fully enter the electrolyte salt into the hydrogel to provide free ions that can be used for conduction, and at the same time, some of the hydrogen bonds in the metal ion hydrogel are Ionic coordination interactions are generated, resulting in new ion coordination crosslinks, thereby enhancing the mechanical properties of the hydrogel.

The second object of the present invention is to provide a high-stretch photocurable ion-conducting hydrogel, which is prepared by the above-mentioned preparation method, and its components include polyvinyl alcohol-styrene pyridinium salt according to the mass fraction percentage (PVA-SbQ), an electrolyte salt and deionized water, wherein the content of the polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) ranges from 8.38% to 14.595% and the content of the electrolyte salt ranges from 2.7% to 16.2 %, the content of deionized water ranges from 75.42% to 82.705%.

The tensile strength of the above-mentioned high tensile photocurable ion conductive hydrogel is 0.136-0.303MPa; the tensile elongation at break is 559%-838%; the electrical conductivity is 0.006-0.31S/m; the room temperature is 32% RH and The water retention rates stored for 10 hours at 75% RH were 35%-60% and 45%-77%, respectively; the resistance change rate was 20% when the finger was bent 90°, and there was no obvious hysteresis.

The third object of the present invention is to provide the application of the above-mentioned high-stretch photocurable ion-conductive hydrogel in the preparation of sensors and wearable devices.

Compared with the prior art, the beneficial effects of the present invention:

(1) The present invention adopts the biocompatible material polyvinyl alcohol-styrene pyridinium salt (PVA~SbQ), and through the two-step method of ultraviolet light curing and introduction of conductive ions, the prepared photocurable ion conductive hydrogel has High stretchability, high transparency, high conductivity, good water retention, good strain sensitivity and biocompatibility. It has broad application prospects in the fields of visual wearable devices, strain sensors, and intelligent artificial skin;

(2) The present invention can adjust the tensile properties and electrical conductivity by adjusting the concentration of electrolyte salt, endow the ion-conducting hydrogel with excellent adjustable mechanical properties and controllable high electrical conductivity, and make the ion-conducting hydrogel It is more widely used in sensors;

(3) The method of the present invention is simple in process, short in production period, mild in reaction conditions, green and environmentally friendly, non-toxic and non-polluting, and can be industrially produced, thereby having good popularization and application value.

Description of drawings

In order to illustrate the technical solutions in the specific embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Figure 1 is the tensile properties of the photocured ionically conductive hydrogels prepared in each example;

Figure 2 is the water retention properties of the photocurable ionically conductive hydrogels prepared in each example at 32% RH;

Figure 3 is the water retention properties of the photocurable ionically conductive hydrogels prepared in each example at 75% RH;

Figure 4 is the electrical conductivity of the photocurable ionically conductive hydrogels prepared in each example;

FIG. 5 shows the sensing properties of the photocured ionically conductive hydrogel prepared in Example 5. FIG.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution in each example was purchased from Shanghai Kaichi Printing Technology Co., Ltd.

Example 1

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/ ^cm2 in a UV curing machine for 6min by light curing, and the obtained hydrogel is placed in a ferric chloride FeCl3 solution with a solubility _of 0.1mol/L at room temperature for 1h. The photocurable ion-conducting hydrogel is obtained, and according to the mass percentage, the content of its component polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) is 14.595%, the content of ferric chloride FeCl ₃ is 2.7%, deionized The water content was 82.705%.

Example 2

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/ ^cm2 in a UV curing machine for 6min by light curing, and the obtained hydrogel is placed in a ferric chloride FeCl3 solution with a solubility _of 0.2mol/L at room temperature for 1h. The photocurable ion-conducting hydrogel is obtained. According to the mass percentage, the content of its component polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) is 13.244%, the content of ferric chloride FeCl ₃ is 5.4%, and the deionized content is 13.244%. The water content was 81.356%.

Example 3

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/ ^cm2 in a UV curing machine for 6min by light curing, and the obtained hydrogel is placed in a ferric chloride FeCl3 solution with a solubility _of 0.3mol/L at room temperature for 1h. The photocurable ion-conducting hydrogel is obtained, and according to the mass percentage, the content of its component polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) is 11.947%, the content of ferric chloride FeCl ₃ is 8.1%, deionized The water content is 79.953%.

Example 4

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/ ^cm2 in a UV curing machine for 6min by light curing, and the obtained hydrogel is placed in a ferric chloride FeCl3 solution with a solubility _of 0.4mol/L at room temperature for 1h. The photocurable ion-conducting hydrogel is obtained. According to the mass percentage, the content of its component polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) is 10.704%, the content of ferric chloride FeCl ₃ is 10.8%, and the deionized content is 10.704%. The water content is 78.496%.

Example 5

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/ ^cm2 in a UV curing machine for 6min by light curing, and the obtained hydrogel is placed in a ferric chloride FeCl3 solution with a solubility _of 0.5mol/L at room temperature for 1h. The photocurable ion-conducting hydrogel is obtained. According to the mass percentage, the content of its component polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) is 9.515%, the content of ferric chloride FeCl ₃ is 13.5%, and the deionized content is 9.515%. The water content is 76.985%.

Example 6

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/cm ² in a UV curing machine for 6min by light curing, and the obtained hydrogel is placed in a ferric chloride FeCl ₃ solution with a solubility of 0.6mol/L at room temperature for 1h. The photocurable ion-conducting hydrogel is obtained. According to the mass percentage, the content of its component polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) is 8.38%, the content of ferric chloride FeCl ₃ is 16.2%, and the deionized content is 8.38%. The water content was 75.42%.

Comparative Example 1

Take 15% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution of polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) with a degree of polymerization of 1700, add deionized water to dilute at room temperature, and stir well A 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was obtained, and then the 10% polyvinyl alcohol-styrene pyridinium salt (PVA-SbQ) solution was loaded into a transparent glass mold and placed at the wavelength of the light source It is 365mm and the intensity is 1600mJ/cm ² in a UV light curing machine for 6 min of light curing to obtain a light curing hydrogel.

The ion conductive hydrogels prepared in Examples 1 to 6 and the comparative example were cut into dumbbell-shaped splines with a size of about 12 mm×2 mm×2 mm. At room temperature, the prepared dumbbell-shaped hydrogel splines were tested for tensile properties using an Instron 5967 universal testing machine manufactured by Instron Testing Equipment Trading Co., Ltd., and the tensile rate was 50 mm/min.

The ion-conducting hydrogels prepared in Examples 1 to 6 and the comparative example were cut into cylindrical samples with a diameter of 10 mm, which were placed in vessels with relative humidity of 32% and 75%, respectively. The gel was removed until the mass of the hydrogel no longer changed. The mass of the sample is weighed and recorded. Calculate the water retention of the hydrogel using the equation:

Water retention rate=Mt/M0×100%

Among them, M0 is the initial mass of the hydrogel, and Mt is the mass of the hydrogel at t.

Use the Keithley2400 digital source meter manufactured by Beijing Saifan Optoelectronics Instrument Co., Ltd. to test and record the resistance of the hydrogel, a group of 5 samples, and take the average value as the final conductivity. The calculation formula is as follows:

δ=0.69314/(3.14×R×d)

Among them, 6 (S/m) represents the conductivity of the material, R (Ω) represents the test resistance, and d (mm) represents the thickness of the sample.

In order to detect the strain response and monitor human motion, the resistance change of the hydrogel was obtained by a CHI-660e electrochemical workstation manufactured by Shanghai Chenhua Instrument Co., Ltd. and a Keithley2400 digital source meter manufactured by Beijing Saifan Optoelectronic Instrument Co., Ltd. The change in resistance is calculated by:

ΔR/R0=(R-R0)/R0×100%

where R0 and R are the unstrained and strained resistances, respectively.

The test data are shown in Figures 1 to 5. Figure 1 shows the tensile properties of the photocured ion conductive hydrogels prepared in each example; Figure 2 shows the photocured ion conductive hydrogels prepared in each example at 32% RH. The water retention performance of the hydrogel; Figure 3 is the water retention performance of the photocured ion conductive hydrogel prepared in each example at 75% RH; Figure 4 is the photocured ion conductive hydrogel prepared in each example. Conductive properties; Figure 5 shows the sensing properties of the photocured ionically conductive hydrogel prepared in Example 5. For the convenience of comparison, the test data are arranged in the following table;

Table 1

As can be seen from Table 1, Comparative Example ₁ did not soak FeCl solution, and Examples 1-6 were soaked in ferric chloride solution, and the hydrogel soaked in ferric chloride solution had better mechanical properties, water retention and electrical conductivity. This is because in the hydrogel obtained by soaking in FeCl solution, the Fe _- SbQ hydrogels obtained by immersion in FeCl3 solution are relatively stable compared to the PVA-SbQ hydrogels formed by photodimerization of styrene pyridinium salts under the action of UV light to form chemically cross-linked networks. ³⁺ enters the hydrogel network and interacts with the abundant hydroxyl groups on PVA-SbQ to form a new ionic coordination cross-linked network, making the originally bound PVA-SbQ hydrogel network denser. tangled together. There are three kinds of interactions in the hydrogel system: chemical cross-linking, ionic coordination cross-linking, and hydrogen bonding. The network formed by these interactions is interpenetrating. When external forces are applied, the ionic coordination bonds in the hydrogel It may be destroyed first, effectively dispersing and absorbing external force energy, and the chemical bonds generated by photodimerization ensure the integrity of the hydrogel structure, thereby achieving stronger mechanical properties than PVA-SbQ hydrogels, and the dense network structure gives hydrogels. The gel has better water retention, and the abundant Fe ³⁺ ions in the system can provide the electrical conductivity of the hydrogel; Examples 1-6 are hydrogels obtained by soaking in different concentrations of FeCl ₃ solutions, and Examples 1-4, along with As the concentration _of FeCl3 solution increases, the free ions in the hydrogel increase and the ion coordination and crosslinking effect is enhanced, so that the hydrogel obtains a denser network structure, and the mechanical properties, water retention and electrical conductivity of the hydrogel increase; Example 4-6, when the concentration of FeCl ₃ solution reaches 0.4mol/L, the hydrogel network structure tends to be stable, and the presence of higher concentration salt solution leads to a large difference in osmotic pressure between the hydrogel and the environment, which leads to hydrogelation. The mechanical properties and water retention properties of the glue decreased slightly.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (7)

1. A preparation method of high-tensile photo-curing ion-conductive hydrogel is characterized by mainly comprising the following steps,

(1) Diluting the polyvinyl alcohol-styrene pyridinium salt solution with deionized water to obtain a pre-gel solution;

(2) Placing the pre-gel liquid in a transparent glass mold, crosslinking in an ultraviolet light curing machine to obtain hydrogel, placing the hydrogel in an electrolyte salt solution for soaking, and carrying out solvent displacement reaction to obtain the photocuring ionic conductive hydrogel;

the electrolyte salt is one of ferric trichloride and aluminum chloride;

the concentration of solute in the electrolyte salt solution is 0.1-0.6 mol/L;

the temperature of the solvent replacement reaction is room temperature, and the time is 1-3 h.

2. The method for preparing a high tensile photo-curing ionic conduction hydrogel according to claim 1, wherein the polymerization degree of the polyvinyl alcohol-styrene pyridinium salt in the polyvinyl alcohol-styrene pyridinium salt solution is 1700.

3. The method for preparing a high-tensile photo-curing ionic-conductive hydrogel according to claim 1, wherein the mass fraction of the solute polyvinyl alcohol-styrene pyridinium salt in the polyvinyl alcohol-styrene pyridinium salt solution is 10% to 15%.

4. The method for preparing high-tensile photo-curing ion-conductive hydrogel according to claim 1, wherein the light source wavelength of the UV curing machine is 365mm, and the intensity is 1600mJ/cm ² 。

5. The method for preparing high-tensile photo-curing ion-conductive hydrogel according to claim 1, wherein the UV curing temperature is room temperature and the curing time is 6min.

6. The high-tensile photocuring ionic-conductive hydrogel is characterized by being prepared by the preparation method of any one of claims 1 to 5, and the components of the hydrogel comprise polyvinyl alcohol-styrene pyridinium salt, electrolyte salt and deionized water, wherein the content of the polyvinyl alcohol-styrene pyridinium salt is 8.38-14.595%, the content of the electrolyte salt is 2.7-16.2% and the content of the deionized water is 75.42-82.705% in percentage by mass.

7. Use of the high tensile photo-curable ionic conducting hydrogel according to claim 6 for the preparation of sensors and wearable devices.

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