CN112961296B

CN112961296B - Organic gel and preparation method and application thereof

Info

Publication number: CN112961296B
Application number: CN202110378307.5A
Authority: CN
Inventors: 徐峰; 牛艳
Original assignee: Suzhou Dianan Biotechnology Co ltd
Current assignee: Suzhou Dianan Biotechnology Co ltd
Priority date: 2021-04-08
Filing date: 2021-04-08
Publication date: 2023-01-31
Anticipated expiration: 2041-04-08
Also published as: CN112961296A

Abstract

The invention relates to an organogel and a preparation method and application thereof, wherein the organogel comprises a cross-linked product of acrylic acid, gelatin and N-hydroxysuccinimide acrylate, and a solvent and an ionic compound coated in the cross-linked product; the solvent comprises water and polyhydric alcohol in a volume ratio of 1 (1-7). The organogel provided by the invention has excellent freezing resistance, high temperature resistance, tensile property and electric conductivity, and the formed device has high adhesion to a human body, accurate and reliable signal acquisition, faster response and recovery speed, and excellent comprehensive performance.

Description

Organic gel and preparation method and application thereof

Technical Field

The invention relates to the technical field of composite materials, in particular to an organogel and a preparation method and application thereof.

Background

The flexible wearable electronic device has been widely used in physiological index monitoring due to its advantages of lightness, thinness, softness and skin friendliness. Among them, hydrogel has become a bridge connecting a human body and an electronic device because of having a modulus matching with a skin of the human body.

However, the hydrogel electronic device is exposed to various changing environmental conditions (such as temperature or humidity) in practical applications, which may cause freezing (low temperature environment) or evaporation (high temperature or dry environment) of water in the internal network structure of the material, resulting in structural and functional damage of the hydrogel electronic device, affecting the stability of the operation and reliability of the acquired data, and in addition, in high humidity environment (such as sweat, underwater, etc.), the firm adhesion of the flexible device to the skin is problematic, and many researches on the modification of the hydrogel and the organic gel are currently being conducted.

CN112220960A discloses a double-layer hydrocolloid dressing and a preparation method thereof, wherein the disclosed preparation method mainly comprises the following steps: 1. carrying out heat preservation banburying on a continuous phase rubber matrix and hydrophilic phase hydrocolloid in a double-screw banbury mixer to obtain a hydrocolloid dressing; 2. pressing the hydrocolloid dressing by a flat vulcanizing machine to form a lower base layer material; 3. coating hydrogel formed by dissolving acrylic acid, gelatin, ketoglutaric acid, methacrylated gelatin and N-hydroxysuccinimide ester in deionized water on the lower-layer base material, and curing under ultraviolet light to obtain the double-layer hydrocolloid dressing. The double-layer hydrocolloid dressing disclosed by the method has better adhesive property and liquid absorption property under a wet environment. The double-layer hydrocolloid dressing disclosed by the method is tightly combined, and cannot be delaminated after being soaked in the prepared wound simulating liquid for 24 hours. Meanwhile, the double-layer hydrocolloid dressing disclosed by the method is non-toxic and harmless to human bodies, simple in preparation process and low in production cost, and can be widely produced and applied. The disclosed two-layer hydrocolloid dressing has limited application in high and low temperature environments.

CN112376317A discloses a preparation method of a low-cost cold-resistant mouse and ant prevention packaging box, the disclosed packaging box has a very good cold-resistant effect due to the addition of a mixed adhesive composed of a water-based acrylic resin, a water-based epoxy modified acrylic resin and a modified melamine formaldehyde resin, and the disclosed packaging box can achieve the effect of repelling mice and ants by adding traditional Chinese medicine components consisting of Qilixiang, camphor leaves, pepper and agastache rugosus; in order to improve the mouse and ant repelling effect of the packaging box at low temperature, the cold-resistant emulsion disclosed by the method can be added with glycerol and ethanol, so that the volatilization effect of the traditional Chinese medicine extract at low temperature can be effectively improved. The disclosed packing box is used poorly in a high temperature and humid environment.

In conclusion, it is important to develop a gel with excellent comprehensive performance of freezing resistance, high temperature resistance, tensile property and electrical conductivity, and the device formed by the prepared gel is required to acquire accurate and reliable signals.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide the organogel, the preparation method and the application thereof, wherein the organogel has excellent freezing resistance, high temperature resistance, tensile property and electric conductivity, the formed device has high adhesion with a human body, the acquired signal is accurate and reliable, and the comprehensive performance is excellent.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an organogel comprising a solvent and an ionic compound in which a crosslinked product of acrylic acid, gelatin and N-hydroxysuccinimide acrylate (AA-NHS) is encapsulated;

the solvent comprises water and polyhydric alcohol in a volume ratio of 1 (1-7), such as 1.

The solvent in the organogel adopts a mixed solvent of water and polyhydric alcohol in a specific ratio, and because hydroxyl in the polyhydric alcohol can compete with water molecules to form hydrogen bonds, part of the polyhydric alcohol is used for replacing water, so that the freezing point and the water evaporation of the material can be reduced, the freezing resistance and the high temperature resistance of the material can be obviously improved, and if the ratio of the polyhydric alcohol is too heavy, the system cannot form gel; if the proportion of the polyhydric alcohol is too light, the realization of the frost resistance and high temperature resistance of the material cannot be ensured. Meanwhile, the ionic compound can improve the conductivity of the organogel, and can be cooperatively matched with the polyol to improve the frost resistance of the organogel due to the water retention effect of the ionic compound. In addition, N-hydroxysuccinimide acrylate is introduced into the organogel, and N-hydroxysuccinimide groups can form covalent bonds with amino groups on human skin, so that the adhesion between an electronic device formed by the organogel and a human body is improved, and the accuracy and reliability of signal acquisition are guaranteed. Therefore, the organogel has excellent freezing resistance, high temperature resistance, tensile property and electric conductivity, and the formed device has high adhesion to a human body, accurate and reliable signal acquisition and excellent comprehensive performance.

Preferably, the polyol comprises ethylene glycol and/or glycerol, preferably glycerol.

The reason why the organic gel is preferably glycerol is that the glycerol replaces part of water and can compete with water molecules to form hydrogen bonds, so that the freezing point of a system is reduced, the evaporation of water is reduced, the tolerance of the gel in a low-temperature environment and a high-temperature or dry environment is greatly improved, and the excellent conductive and tensile properties of a gel device can be guaranteed under various environmental conditions.

The polyol of the present invention refers to dihydric and higher alcohols.

Preferably, the mass fraction of the crosslinked product in the organogel is 33.5% to 49%, such as 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, etc.

Preferably, the ionic compound comprises sodium chloride (NaCl), calcium chloride (CaCl) ₂ ) Or lithium chloride (LiCl), preferably lithium chloride.

Preferably, the mass fraction of the ionic compound in the organogel is between 10% and 15%, such as 11%, 12%, 13%, 14%, etc.

The mass fraction of the ionic compound in the organogel is 10% -15%, the addition of the ionic compound in the range can give consideration to both the conductivity and the frost resistance of the system, and the excessive proportion of the ionic compound can influence the tensile property of the system.

In a second aspect, the present invention provides a process for the preparation of an organogel according to the first aspect, said process comprising the steps of: crosslinking acrylic acid, gelatin and N-hydroxysuccinimide acrylate in a solvent, and soaking a crosslinked product of the acrylic acid, the gelatin and the N-hydroxysuccinimide acrylate containing the solvent in an ionic compound solution to obtain the organogel;

the solvent includes water and a polyol in a volume ratio of 1 (1-7), for example, 1.

The method for introducing the ionic compound into the organic gel is to soak the crosslinked product in the solution of the ionic compound, and the method is not only simple and easy to operate, but also avoids the influence of the direct addition of the ionic compound on other properties of the organic gel during crosslinking.

Preferably, the crosslinking process further comprises adding an auxiliary agent.

Preferably, the auxiliary agent comprises a cross-linking agent and/or an initiator.

Preferably, the cross-linking agent comprises methacrylic acid gelatin (GelMA).

Preferably, the initiator comprises alpha-ketoglutaric acid.

Preferably, the mass ratio of the acrylic acid to the gelatin to the N-hydroxysuccinimide acrylate is (8-12): (25-35): 1, wherein 8-12 can be 9, 10, 11, etc., and 25-35 can be 26, 28, 30, 32, 34, etc., preferably 10.

Preferably, the time for crosslinking is 15-25min, such as 16min, 18min, 20min, 22min, 24min, etc.

Preferably, the means of crosslinking comprises uv crosslinking.

Preferably, the power of the light source in the ultraviolet crosslinking is 5-10W, such as 6W, 7W, 8W, 9W, etc., preferably 8W.

Preferably, the wavelength of the light source in the ultraviolet crosslinking is 200-500nm, such as 250nm, 300nm, 350nm, 400nm, 450nm and the like, preferably 254nm.

Preferably, the concentration of the ionic compound solution is 1 to 10mol/L, such as 2mol/L, 3mol/L, 4mol/L, 5mol/L, 6mol/L, 7mol/L, 8mol/L, 9mol/L, etc., preferably 2.5mol/L.

Preferably, the soaking time is more than 24h, such as 26h, 28h, 30h, 32h and the like, preferably 24h.

As a preferable technical scheme, the preparation method comprises the following steps:

(1) Uniformly mixing acrylic acid, gelatin, N-hydroxysuccinimide acrylate and a cross-linking agent in a mixed solvent of water and polyhydric alcohol with the volume ratio of 1 (1-7) to obtain a mixed solution;

(2) Carrying out ultraviolet crosslinking on the mixed solution obtained in the step (1) for 15-25min under the conditions that the power of an ultraviolet light source is 5-10W and the wavelength is 200-500nm to obtain a crosslinked product;

(3) And (3) soaking the crosslinked product obtained in the step (2) in an ionic compound solution with the concentration of 1-10mol/L for 12-36h to obtain the organogel.

In a third aspect, the present invention provides a strain sensor comprising the organogel of the first aspect.

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

the organogel provided by the invention has excellent freezing resistance, high temperature resistance, tensile property and electric conductivity, and the formed device has high adhesion to a human body, accurate and reliable signal acquisition and excellent comprehensive performance. Moreover, the organogel of the present invention has faster response and recovery speed, response within 116ms and recovery within 68 ms.

Drawings

FIG. 1 is a scanning electron micrograph of the organogel of example 2.

FIG. 2 is a schematic representation of the organogel of example 2 after one week at room temperature.

FIG. 3 is a visual representation of the tensile set test of the organogel of example 2 after one week at room temperature.

FIG. 4 is a visual representation of the flexural deformation test after one week at room temperature for the organogel described in example 2.

FIG. 5 is a visual representation of the torsional deformation test after the organogel described in example 2 has been left for one week at room temperature.

FIG. 6 is a graph of stress-strain relationship for organogels described in example 2 at various temperatures.

FIG. 7 is a statistical chart of the impedance measurements of the organogel of example 2 at different temperatures.

FIG. 8 is a statistical chart of the organogel adhesion test results described in example 2.

FIG. 9 shows the rate of change of resistance (. DELTA.R/R) of the organogel of example 2 at different draw ratios ₀ ) And (5) characterizing the graph.

FIG. 10 is the Δ R/R of the organogel of example 2 during cyclic stretching ₀ And (5) characterizing the graph.

FIG. 11 is Δ R/R at cyclic stretching for the organogel of example 2 ₀ The characterization map is enlarged partially.

FIG. 12 is a graph representing response time of a strain sensor prepared from the organogel described in example 2.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The invention provides an organogel which consists of acrylic acid, gelatin (available from sigma aldrich, under the trademark 73865 MSDS) and a crosslinked product of N-hydroxysuccinimide acrylate (41% by mass), water, glycerol and LiCl (10% by mass);

the volume ratio of water to glycerol is 1.

The preparation method of the organogel comprises the following steps:

(1) Weighing 1g of acrylic acid, 3g of gelatin, 0.1g of AA-NHS, 0.1g of GelMA and 0.04g of alpha-ketoglutaric acid by using a balance, adding into a mixed solvent of 2880 mu L of water and glycerol respectively, and stirring until the mixture is uniformly mixed to obtain a precursor solution;

(2) Injecting 1mL of precursor solution into a polymethyl methacrylate (PMMA) mold with the length of 20mm, the width of 10mm and the thickness of 2mm, discharging bubbles, and then putting into an ultraviolet crosslinking instrument with the light source power of 8W and the wavelength of 254nm for crosslinking for 20min;

(3) And demolding the crosslinked organogel, and soaking the crosslinked organogel in a LiCl solution with the concentration of 1mol/L for 24 hours to obtain the organogel.

Example 2

This example is different from example 1 in that the ionic compound content is 15% by mass, and the LiCl solution used in the preparation has a concentration of 2.5mol/L, and is the same as example 1.

Example 3

This example is different from example 1 in that the ionic compound content is 15% by mass, and the LiCl solution used in the preparation has a concentration of 5mol/L, and the rest is the same as example 1.

Example 4

This example is different from example 1 in that the ionic compound content is 15% by mass, and the LiCl solution used in the preparation has a concentration of 10mol/L, and the rest is the same as example 1.

Example 5

This example is different from example 1 in that LiCl is 1% by mass in the organogel, and LiCl solution is used in the preparation at a concentration of 0.5mol/L, and the rest is the same as example 1.

Example 6

This example is different from example 1 in that LiCl is present in the organogel in a mass percent of 17% and the LiCl solution used in the preparation is present in a concentration of 12mol/L, the rest being the same as example 1.

Comparative example 1

This comparative example differs from example 2 in that the solvents are water and glycerol in a volume ratio of 1.

Comparative example 2

This comparative example differs from example 2 in that the solvent is water only, and the rest is the same as example 2.

Comparative example 3

This comparative example differs from example 2 in that the crosslinked product is a crosslinked product of acrylic acid and gelatin, the mass ratio of acrylic acid and gelatin in the preparation is 1.1.

Comparative example 4

This comparative example differs from example 2 in that the organogel does not include an ionic compound, the preparation process does not include step (3), and the rest is the same as example 2.

Performance testing

Examples 1-6 and comparative examples 1-4 were tested as follows:

(1) Microscopic morphology: and observing the microstructure of the organic gel by using a scanning electron microscope.

(2) Mechanical properties:

(1) placing the ionic conduction organogel in an environment with room temperature of 25 ℃ and relative humidity of 40% for a week, and observing the performance of the ionic conduction organogel under various mechanical loads;

(2) the organogel is tested by a universal tensile machine to obtain the breaking tensile property at room temperature (25 ℃), low temperature (-20 ℃) and high temperature (60 ℃).

(3) Conductivity:

(1) testing the impedance of the gel at different temperatures by using a multimeter;

(2) the prepared gel with the size of 20mm in length, 10mm in width and 2mm in thickness is used as a variable resistor to be connected in series in a circuit containing a fixed resistor, in the process of stretching the two ends of the gel, the voltage at the two ends of the gel is detected by an oscilloscope and converted into a resistance value, and the relative resistance change of the gel under different stretching states is calculated;

(3) fitting a relation graph of the stretching length and the relative resistance by measuring and calculating the relative resistance change of the gel in different stretching states;

(4) the gel is stretched to the same length in a multiple-cycle manner, and the change of the relative resistance of the cycle stretching along with the time is drawn, so that the gel is stable in performance after multiple-cycle stretching;

(5) the gel was rapidly stretched to a certain length, the relative resistance was plotted against time, and the response time of the gel strain sensor was recorded.

(4) Adhesion performance:

(1) bonding the prepared ionic conductive organic gel with pigskins with the same size, and presetting a non-adhesion area with the length of 10mm at one end for connecting a clamp;

(2) respectively placing the adhered samples in air and water, and taking out to be tested after 2 hours;

(3) and respectively connecting the gel at the non-adhesion area end and the pigskin with a clamp, performing a tensile test at a tensile speed of 0.15mm/s, drawing a graph of the change relation between displacement and adhesion force, and calculating the adhesion strength by the formula 2 x the displacement-force curve to reach the width of the force/sample corresponding to the plateau period.

(5) Thermal properties: the freezing point of the organogel was tested with a differential scanning calorimeter.

The test results are summarized in FIGS. 1-12 and tables 1-2.

TABLE 1

TABLE 2

As can be seen from the analysis of tables 1 and 2, the organogel disclosed by the invention has excellent freezing resistance, high temperature resistance, tensile property and electric conductivity, and the formed device has high adhesion to a human body, accurate and reliable signal acquisition and excellent comprehensive performance.

As can be seen from the analysis of comparative examples 1-2 and example 2, comparative examples 1-2 are inferior to example 2 in performance, and it was confirmed that the organogel prepared using the mixed solvent in the volume ratio range of 1 (1-7) is superior in overall performance.

As can be seen from the analysis of comparative example 3 and example 2, comparative example 3 is inferior in performance to example 2, demonstrating that organogels prepared without the addition of AA-NHS have a poor combination of properties.

As can be seen from the analysis of comparative example 4 and example 2, comparative example 4 is inferior in performance to example 2, demonstrating that organogels prepared without the addition of ionic compounds have inferior overall performance.

As can be seen from the analysis of examples 5-6 and example 2, the performance of examples 5-6 is inferior to that of example 2, and the comprehensive performance of the organogel prepared by the mass fraction of the ionic compound in the organogel of 10% -15% is more excellent.

As can be seen from the analysis of FIG. 1, the organogel of the present invention has a porous structure.

As can be seen from the analysis of FIGS. 2 to 5, the organic gel of the present invention has good flexibility after being placed at room temperature for one week, and can endure various deformation effects such as stretching, bending and twisting.

As can be seen from the analysis of FIG. 6, the organogel of the present invention has good elasticity at room temperature, low temperature and high temperature, and the breaking strain reaches 600% -900%.

As can be seen from the analysis of FIG. 7, the organogel of the present invention has satisfactory resistance values at different temperatures.

As can be seen from the analysis of FIG. 8, the organogel of the present invention has better adhesion strength under underwater or dry conditions.

In FIG. 9, R ₀ The resistance of the gel without stretching, and Δ R is the real-time resistance change (i.e., relative to R) corresponding to different lengths of the gel stretched ₀ Variation of (c) in fig. 9, it can be seen that the organogel of the present invention has good sensitivity in the range of strain of 0-300%,and excellent in linearity (R) ² ＝0.982)。

As can be seen from the analysis of FIG. 10 and FIG. 11, the organogel of the present invention is stretched to the same length in multiple cycles, and the change of the relative resistance with time is relatively stable, which indicates that the organogel of the present invention has stable stretching performance in multiple cycles.

As can be seen from the analysis of FIG. 12, the organogel of the present invention responds within 116ms and recovers within 68ms, which shows that the organogel of the present invention has faster response and recovery speed.

The applicant states that the present invention is illustrated by the above examples to show the detailed method of the present invention, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be carried out. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. An organogel comprising acrylic acid, gelatin, andN-a cross-linked product of hydroxysuccinimide acrylate and a solvent and an ionic compound encapsulated in the cross-linked product;

the solvent comprises water and polyhydric alcohol in a volume ratio of 1 (1-7).

2. Organogel according to claim 1, characterized in that said polyol comprises ethylene glycol and/or glycerol.

3. The organogel of claim 2, wherein the polyol is glycerol.

4. The organogel of claim 1, wherein the crosslinked product has a mass fraction in the organogel of from 33.5% to 49%.

5. Organogel according to claim 1, characterized in that the ionic compound comprises any of sodium chloride, calcium chloride or lithium chloride.

6. Organogel according to claim 5, characterized in that said ionic compound is lithium chloride.

7. The organogel of claim 1, wherein the ionic compound is present in the organogel in an amount of from 10% to 15% by weight.

8. A process for the preparation of an organogel according to any of claims 1 to 7, characterized in that it comprises the following steps: mixing acrylic acid, gelatin andN-hydroxysuccinimide acrylate is crosslinked in a solvent, and acrylic acid, gelatin and solvent are mixed withN-immersing the crosslinked product of hydroxysuccinimide acrylate in a solution of an ionic compound to obtain the organogel;

9. The method of claim 8, wherein the cross-linking process further comprises adding an auxiliary agent.

10. A method of manufacturing as claimed in claim 9, wherein the auxiliary agent comprises a cross-linking agent and/or an initiator.

11. The method of claim 10, wherein the cross-linking agent comprises methacrylic gelatin.

12. The method of claim 10, wherein the initiator comprises α -ketoglutaric acid.

13. The method according to claim 8, wherein the acrylic acid, gelatin andNthe mass ratio of the hydroxyl succinimide acrylate to the hydroxyl succinimide acrylate is (8-12) to (25-35) to 1.

14. The method of claim 8, wherein the cross-linking time is 15-25 min.

15. The method of claim 8, wherein the crosslinking comprises ultraviolet crosslinking.

16. The method according to claim 15, wherein the power of the light source in the UV crosslinking is 5-10W.

17. The method according to claim 15, wherein the wavelength of the light source in the uv crosslinking is 200 to 500 nm.

18. The method according to claim 8, wherein the concentration of the ionic compound solution is 1 to 10 mol/L.

19. The method according to claim 8, wherein the soaking time is 24 hours or more.

20. The method of claim 8, comprising the steps of:

(1) Mixing acrylic acid, gelatin,NUniformly mixing hydroxy succinimide acrylate and a cross-linking agent in a mixed solvent of water and polyhydric alcohol with the volume ratio of 1 (1-7) to obtain a mixed solution;

21. A strain sensor, characterized in that the strain sensor comprises the organogel according to any of claims 1 to 7.