CN113527862A - Stretchable conductive composite material based on liquid metal and preparation method thereof - Google Patents
Stretchable conductive composite material based on liquid metal and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a stretchable conductive composite material based on liquid metal and a preparation method thereof, wherein the stretchable conductive composite material is prepared by the following steps: preparing liquid metal into micro-nano particle/solvent dispersion liquid, soaking the sponge with the modified surface into the dispersion liquid, taking out the sponge/dispersion liquid compound, drying the dispersing agent, volatilizing the dispersing agent, and performing laser sintering or pressure sintering on the liquid metal coated on the surface of the sponge skeleton to prepare the stretchable conductive composite material. The invention solves the problem that the nano conductive filler in the traditional stretchable conductive composite material can not adapt to large deformation; the blending type liquid metal stretchable conductive composite material has the problems of large liquid metal consumption, poor conductivity and difficult large-scale application; the problem that the liquid metal of the filled type liquid metal stretchable conductive composite material is easy to overflow due to the lack of interface design with a matrix. The preparation method can be used for obtaining the stretchable conductive composite material with high conductivity, high conductive stability and low liquid metal consumption.
Description
Technical Field
The invention relates to the field of flexible conductive materials, in particular to a stretchable conductive composite material, and especially relates to a stretchable conductive composite material based on liquid metal and a preparation method thereof.
Background
With the development of wearable field, flexible electronic products such as foldable and rollable screens, flexible robots, flexible sensors, and flexible energy converters have higher requirements for flexible conductors. The development of high performance stretchable conductors that are resistant to large deformation, low in the amount of conductive components and high in conductivity has become one of the key tasks. The stretchable conductor with good performance is easy to prepare by compounding the nano conductive filler and the elastomer prefabricated three-dimensional network, and is more and more favored, and common nano conductive fillers comprise: conductive Carbon Black (CB), graphene, carbon nanotubes, metal nanowires, nanoparticles, and the like. Although the conductive material and the elastomer prefabricated three-dimensional network can reduce the using amount of the conductive filler and improve the conductive performance after being compounded, the conductive path is disabled due to the fact that the nano filler in the composite material increases the gaps among the nano fillers under large deformation, and finally the service life of the stretchable conductive composite material is greatly shortened, so that the application of the stretchable conductive composite material in the stretchable conductive field is limited.
Gallium-based liquid metal alloys, such as gallium-indium alloy (EGaIn) and gallium-indium-tin alloy (Galinstan), are nontoxic Liquid Metals (LM), have a low melting point (MP ═ 15 ℃), and high electrical conductivity (σ ═ 3.4 × 10 ℃6S m-1) Low viscosity (. eta. about.2 mPas). In recent years, in order to solve the problem that the nano conductive filler cannot adapt to large deformation, liquid metal is applied to the stretchable conductor. Zhou et al (Liquid metals gels for mechanical-Dual, All-Soft, electric conductors. J. Mater. chem. C2016, 5(7),1586-1590) propose a method of injecting Liquid Metal into channels in a preformed polydimethylsiloxane rubber sponge to prepare a stretchable conductive material, but this method lacks Liquid Metal and matrixThe interface design and easy overflow are not favorable for application and popularization. Chinese patent CN108198665A "a method for preparing elastic conductor" proposes a method for preparing stretchable conductor by blending liquid metal and elastomer, but this method uses a large amount of expensive liquid metal and has poor conductivity, thus making it difficult to apply it on a large scale.
Disclosure of Invention
In order to solve the technical problems, the invention provides a stretchable conductive composite material based on liquid metal and a preparation method thereof, wherein the stretchable conductive composite material is formed by compounding a liquid metal layer and elastomer sponge; the liquid metal layer is formed by sintering liquid metal micro-nano particles, and the technical problem solved is as follows: (1) the problem that the nano conductive filler in the traditional stretchable conductive composite material cannot adapt to large deformation; (2) the blending type liquid metal stretchable conductive composite material has the problems of large liquid metal consumption, poor conductivity and difficult large-scale application; (3) the filled liquid metal stretchable conductive composite material has the problem that the liquid metal and the matrix lack interface design and are easy to overflow.
It is an object of the present invention to provide a stretchable conductive composite based on liquid metal.
The stretchable conductive composite material based on the liquid metal comprises a liquid metal layer and an elastomer sponge matrix, wherein the liquid metal layer is distributed on the surface of an elastomer sponge framework; the volume percentage of the liquid metal layer is 0.5-15%, preferably 8-14% calculated by the apparent volume of the elastomer sponge;
wherein the liquid metal is eutectic point alloy with melting point lower than 25 ℃, preferably one or two of gallium indium alloy and gallium indium tin alloy; the porosity of the elastomer sponge is 45-95%, preferably 50-90%;
the stretchable conductive composite material is characterized in that a liquid metal layer in the stretchable conductive composite material is formed by sintering liquid metal micro-nano particles;
the elastomer sponge is polydopamine surface modified elastomer sponge, preferably one or more of polydopamine surface modified polydimethylsiloxane sponge, polyurethane sponge or latex sponge. After the polydopamine is modified, the sponge and the liquid metal are combined more tightly, the liquid metal is coated more uniformly, leakage is reduced, and the conductivity is better.
The invention also aims to provide a preparation method of the stretchable conductive composite material based on the liquid metal.
The preparation method provided by the invention comprises the following steps: preparing the liquid metal into liquid metal micro-nano particle dispersion liquid, dipping the elastomer sponge into the dispersion liquid, taking out the elastomer sponge/dispersion liquid compound, drying, and then performing pressure sintering or laser sintering to obtain the stretchable conductive composite material. The preparation method specifically comprises the following steps:
step 1, adding the liquid metal into a dispersing agent, adding a sulfhydryl compound after ultrasonic crushing, and mixing to form a liquid metal micro-nano particle dispersion liquid;
step 2, placing the elastomer sponge in a buffer solution dissolved with dopamine to be fully soaked at room temperature to obtain polydopamine-modified elastomer sponge;
step 3, dipping the modified elastomer sponge obtained in the step 2 into the liquid metal micro-nano particle dispersion liquid prepared in the step 1 at room temperature, fully dipping and drying to obtain the modified elastomer sponge coated with the liquid metal micro-nano particles;
and 4, performing laser sintering or pressure sintering on the modified elastomer sponge coated with the liquid metal micro-nano particles obtained in the step 3 to obtain the stretchable conductive composite material.
In the step 1, the liquid metal is eutectic point alloy with a melting point lower than 25 ℃, preferably one or two of gallium indium alloy and gallium indium tin alloy;
the dispersant is at least one of water and an organic solvent, the organic solvent is at least one of ether, furan, ketone and alcohol, and preferably at least one of diethyl ether, acetone, ethanol, isopropanol and tetrahydrofuran;
the concentration of the liquid metal in the dispersion liquid is 0.01-0.2 g/ml, preferably 0.02-0.15 g/ml;
the mercapto compound is at least one of organic compounds containing mercapto and carboxyl, organic compounds containing mercapto and amino, and organic compounds containing mercapto and carbonyl; preferably at least one of thioglycolic acid, mercaptopropionic acid, 4-mercaptobutyric acid, 8-mercaptoheptanoic acid, 11-mercaptoundecanoic acid, mercaptoethylamine, 3-mercapto-1-propylamine, 1-mercapto-2-acetone, 4-mercapto-2-pentanone, and 3-mercapto-2-butanone;
the concentration of the sulfhydryl compound in the dispersion liquid is 1-25 mM, preferably 1-20 mM;
ultrasonic crushing is carried out in a water bath at the temperature of 0-10 ℃ for 0.5-2 h; the power of ultrasonic crushing is preferably 1000-1500W, the preferred temperature is 0-5 ℃, and the preferred time is 0.5-1 h; carrying out ultrasonic crushing to obtain liquid metal micro-nano particles with the average particle size of 20-1000 nm, wherein the liquid metal micro-nano particles are dispersed in a dispersing agent;
the step 1 of mixing to form the liquid metal micro-nano particle dispersion liquid comprises the following steps: carrying out ultrasonic treatment on the mixture containing the liquid metal micro-nano particles, the dispersing agent and the mercapto compound in a water bath at the temperature of 0-40 ℃ for 10-50 min to obtain a stable liquid metal micro-nano particle dispersion liquid; centrifuging the liquid metal micro-nano particle dispersion liquid subjected to ultrasonic treatment at a centrifugation rate of 500-3500 r/min for 10-30 min, preferably 25-35 min; and removing liquid from the liquid metal micro-nano particle dispersion liquid, adding the dispersing agent again, and carrying out ultrasonic treatment after repeated washing to obtain the stable liquid metal particle dispersion liquid.
In the step 2), the elastomer sponge is a polydopamine surface modified elastomer sponge, preferably one or more of a polydopamine surface modified polydimethylsiloxane sponge, a polyurethane sponge or a latex sponge;
before dipping the elastomer sponge, cleaning and drying the elastomer sponge by using water or ethanol, wherein the drying temperature is 50-80 ℃;
the buffer solution is a tris (hydroxymethyl) aminomethane hydrochloric acid buffer aqueous solution, and the pH value of the buffer solution is 7.5-9;
the concentration of the dopamine in the buffer solution is 0.01-0.5 mol/ml, preferably 0.05-0.3 mol/ml;
the dipping time of the elastomer sponge is 1-32 hours.
In step 2), the elastomer sponge is modified by immersing the elastomer sponge in a solution of dissolved dopamine, which polymerizes on the surface of the elastomer sponge at the pH.
In the step 3), before dipping the liquid metal micro-nano particle dispersion liquid, cutting the modified elastomer sponge into blocks, sheets or strips; then dipping the sponge into the dispersion liquid, taking out the modified elastomer sponge dipped in the dispersion liquid, and drying the sponge in an oven at the temperature of 60-80 ℃ for 10-30 min; preferably, the elastomer sponge impregnated with the dispersion is inverted at a frequency of 1/20 min to 1/1 min, preferably 1/15 min to 1/1 min, during drying; and repeating the steps of drying the soaked modified elastomer sponge for 1-40 times.
In the step 4), the sponge is placed at 5-10J/cm2The laser sintering is preferably 7 to 9J/cm2Or mechanically sintering at 10-50 deg.C and 100-1000N pressure, preferably 10-40 deg.C and 500-1000N.
The polydopamine modified elastomer sponge soaked with the liquid metal dispersion liquid is sintered, liquid metal micro-nano particles can be sintered on the surface of the modified sponge, and the polydopamine is coated by the liquid metal.
The laser sintering and the pressure sintering both belong to physical sintering, and the material composition of the liquid metal is not changed, but is changed in physical form. When laser or pressure is applied, the oxide film on the surface of the liquid metal micro-nano particles is broken, and the liquid metal micro-nano particles form a continuous coating layer.
According to the liquid metal micro-nano particle modified by the mercapto bifunctional compound, the mercapto bifunctional compound forms a monolayer on the surface of the particle in a self-assembly manner, so that on one hand, the fusion of liquid drops can be reduced, and the interaction with poly-dopamine can be formed, on the other hand, the interfacial force between the liquid metal and a sponge matrix can be increased, so that the coating amount and the uniformity of the liquid metal micro-nano particle on the surface of a sponge framework are improved, the capability of adapting to large deformation of the sintered liquid metal layer is improved, the leakage of the liquid metal is reduced, and the electric conductivity of the composite material is finally improved and the using amount of the liquid metal is reduced.
According to the stretchable conductive composite material based on the liquid metal, when the elastomer sponge is used as a substrate, delta R/R is obtained under 50% deformation after stretching02 percent, and the conductivity can reach about 500S cm at the volume fraction of 14 percent of liquid metal-1The conductive material has excellent conductive stability, low liquid metal consumption and high conductive performance, and solves the problem of large overflow of liquid metal.
Compared with the prior art, the invention has the following beneficial effects:
1. compared with the traditional stretchable conductive composite material, the stretchable conductive composite material provided by the invention has the advantages that the liquid metal is more uniformly coated, the conductivity is better, the conductivity is more stable under tensile strain, and the delta R/R is changed under 50% of stretching0Is 2%;
2. compared with the traditional blending type stretchable conductive composite material, the stretchable conductive composite material provided by the invention has the advantages that the high conductivity of the composite material can be realized under the condition of low liquid metal consumption due to the existence of the high-efficiency liquid metal three-dimensional network: the conductivity can reach about 500S cm at the liquid metal volume fraction of 14 percent-1. This is advantageous for reducing costs and facilitating large-scale application of the stretchable conductive composite;
3. the preparation method of the stretchable conductive composite material provided by the invention improves the compatibility and the adhesive force of the liquid metal and the sponge matrix through effective interface design, and solves the problem that the liquid metal of the filling type liquid metal stretchable conductive composite material is easy to overflow in a large amount.
Drawings
FIG. 1 is a scanning electron micrograph of a polyurethane sponge and a polydopamine modified polyurethane, wherein the left figure shows the surface of the polyurethane sponge, and the right figure shows the surface of the polydopamine modified polyurethane sponge;
fig. 2 scanning electron microscope images of the conductive composite material precursors obtained in examples 5 and 6, wherein the left image uses polyurethane as a substrate, and the right image uses polydopamine modified polyurethane as a substrate, it can be seen that the coating of the liquid metal micro-nano particles modified by dopamine is more dense and uniform.
Detailed Description
While the present invention will be described in detail with reference to the following examples, it should be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the present invention.
The invention is further described with reference to the following examples:
description of related Performance tests:
the method for measuring the particle size of the liquid metal is to utilize Dynamic Light Scattering (DLS) to test the particle size distribution and the average diameter, and the used instrument is a Malvern laser particle size analyzer, which comprises the following steps: 3ml of the liquid metal dispersion liquid is taken and poured into a four-light-transmission cuvette, and the four-light-transmission cuvette is placed into a laser particle sizer for testing, so that the particle size distribution and the average diameter of the liquid metal are measured.
The microscopic morphology of the conductive composite material precursor is observed by a scanning electron microscope of Hitachi S-4800.
The conductivity of the conductive composite was measured by a four-wire mode of the Gishili 2450 digital Source Meter. The sample size was: at 5cm x 1cm x 0.2cm, alligator clips were loaded across the material and the resistance was measured by the formula: δ L/(R × S). Wherein L is the distance between the alligator clips, R is the measured resistance, and S is the cross-sectional area of the sample in the current direction.
The resistance change of the conductive composite material during stretching is obtained by combining a Jewel 2450 digital source meter and a tension machine (CMT4104) of Shenzhen SANs company, the conductive wires pulled at two ends are connected to the digital source meter by using crocodile clips after the splines are clamped on the clips, the material is stretched at the stretching rate of 30mm/min, and the digital source meter records the resistance change of the material.
Example 1: LM (liquid metal volume fraction) 0.5%
Preparing a stretchable conductive composite material precursor based on nano liquid metal by using polydopamine modified polyurethane sponge as a substrate.
(1) 0.7g of EGaIn liquid metal (liquid metal available from alfa, which has the composition Ga:65 wt% of In, 35 wt% of In and 6.359g/cm of density3Adding into 35ml of absolute ethanol at the melting point of 10.7 ℃, carrying out ultrasonic pulverization for 30min under 1500W in an ice-water bath, adding 2 mu L of mercaptopropionic acid (the mercaptopropionic acid is purchased from Shanghai Aladdin Biotechnology GmbH, the purity is more than 99.8%), and carrying out ultrasonic pulverization for 30min under a normal-temperature water bath. And placing the obtained dispersion liquid into a centrifugal tube, centrifuging for 30min at 3000r/min, removing supernatant, adding absolute ethyl alcohol, and centrifuging and cleaning for 2-3 times to obtain the nano liquid metal dispersion liquid with the average particle size of about 550 nm.
(2) The polyurethane sponge (commercial polyurethane sponge, the porosity of which is 85%) is washed 2-3 times with deionized water or ethanol, and after drying at 60 ℃, the polyurethane sponge is placed in a buffered aqueous solution of Tris-HCl (Tris-hydroxymethyl-aminomethane, the purity of which is more than 99.8%, and the dopamine is purchased from alfa corporation) dissolved in the buffered aqueous solution for 24 hours (Tris-hydroxymethyl-aminomethane hydrochloric acid buffer solution), the concentration of the dopamine is 0.05mol/ml, and the pH of the buffer solution is 8.5. And washing the modified sponge with deionized water and drying.
(3) Cutting polydopamine modified polyurethane sponge into strips (5cm x 1cm x 0.2cm), soaking in the nanometer liquid metal dispersion, taking out, placing in an oven at 65 deg.C for 30min, and uniformly distributing the liquid metal at a reversal frequency of 1/15 min.
(4) And (3) soaking the polyurethane sponge sample strip modified by polydopamine in the liquid metal dispersion liquid for 5 times to obtain a stretchable conductive composite material precursor based on the micro-nano liquid metal with the liquid metal volume fraction of 0.5%, and mechanically sintering under the pressure of 1000N to fuse the micro-nano particles of the liquid metal together to form a liquid metal layer, thus preparing the stretchable conductive composite material.
Example 2: LM 5%
The preparation method is the same as example 1, except that: after 1g of EGaIn liquid metal is subjected to ultrasonic grinding, 5 mu L of mercaptopropionic acid is added; the concentration of the dopamine in the step (2) is 0.1 mol/ml; step (3) uniformly distributing the liquid metal at a reversal frequency of 1 time/10 min to obtain a stretchable conductive composite material precursor based on the micro-nano liquid metal, wherein the volume fraction of the liquid metal is 5%; and (4) performing mechanical sintering under the pressure of 800N, wherein the test method is the same as that of the example 1, and the test results are shown in the table 1.
Example 3: LM 9.5%
The preparation method is the same as example 1, except that: after 1.3g of EGaIn liquid metal is subjected to ultrasonic grinding, 8 mu L of mercaptopropionic acid is added; the concentration of the dopamine in the step (2) is 0.15 mol/ml; uniformly distributing the liquid metal at the reversal frequency of 1 time/5 min to obtain a stretchable conductive composite material precursor based on the micro-nano liquid metal, wherein the volume fraction of the liquid metal is 9.5%; step (4) mechanical sintering was carried out under 650N, the test method was the same as in example 1, and the test results are shown in Table 1.
Example 4: LM 14%
The preparation method is the same as example 1, except that: after 1.6g of EGaIn liquid metal is subjected to ultrasonic grinding, 11 mu L of mercaptopropionic acid is added; the concentration of the dopamine in the step (2) is 0.2 mol/ml; uniformly distributing the liquid metal at the reversal frequency of 1 time/5 min to obtain a stretchable conductive composite material precursor based on the micro-nano liquid metal, wherein the volume fraction of the liquid metal is 14%; and (4) performing mechanical sintering under the pressure of 500N, wherein the test method is the same as that of the example 1, and the test results are shown in the table 1.
Comparative example 1:
thermoplastic polyurethane elastomer TPU 85A (available from Basff) is used as an elastomer matrix, 5g of TPU is dissolved in Tetrahydrofuran (THF) at a concentration of 20% by mass fraction, 4.45g of liquid metal is added, stirring is carried out at 300r/min for 5h, the mixture is placed in a polytetrafluoroethylene mold and placed at 60 ℃ for 24h to remove the solvent, and a liquid metal/elastomer composite material with the volume fraction of the liquid metal of 14% and the volume fraction of dozens of micrometers is prepared. The test method was the same as in example 1, and the test results are shown in Table 1.
Comparative example 2:
the comparative example was prepared in the same manner as in example 1, except that 1.575g of silver nanowires (AgNW) were added to 35ml of absolute ethanol in step (1), and subjected to ice-water bath and sonication for 30min to prepare an AgNW dispersion. The final composite test results are shown in table 1.
TABLE 1 comparison of the Performance of examples 1-4 with that of comparative example 1
| Conductivity (S/cm) | Delta R/R at 50% elongation0(％) | |
| Example 1 | 0.7 | 132 |
| Example 2 | 39.0 | 76 |
| Example 3 | 132.0 | 15 |
| Example 4 | 497.7 | 2 |
| Comparative example 1 | Is not conductive | 0 |
| Comparative example 2 | 10.0 | 390 |
As can be seen from the data in Table 1, the present invention was adoptedCompared with the stretchable conductive composite material prepared by the traditional nano filler, the liquid metal stretchable conductive composite material prepared by the method has delta R/R under large stretching deformation0A 50-fold decrease and nearly a 50-fold increase in conductivity. The liquid metal stretchable conductive composite material prepared by the method provided by the invention has stable conductive stability and good adaptability to deformation. In addition, the composite material prepared by the blending method does not form a conductive network under the condition of low liquid metal content, and the method shows high conductivity and high conductive stability under the condition of the same liquid metal content, so the method has obvious advantages.
Example 5:
polyurethane sponge is used as a matrix to prepare the stretchable conductive composite material precursor based on micro-nano liquid metal.
(1) 5.575g of EGaIn liquid metal (liquid metal available from alfa, having a composition of Ga: In 65 wt%: 35 wt% and a density of 6.359 g/cm)3Melting point of 10.7 ℃) into 35ml of absolute ethyl alcohol, carrying out ultrasonic pulverization for 30min under 1500W in ice-water bath, adding 21 mu L of mercaptopropionic acid, and carrying out ultrasonic pulverization for 30min under normal-temperature water bath. And placing the obtained dispersion liquid into a centrifugal tube, centrifuging for 30min at 3000r/min, removing supernatant, adding absolute ethyl alcohol, and centrifuging and cleaning for 2-3 times to obtain the nano liquid metal dispersion liquid with the average particle size of about 550 nm.
(2) Washing the polyurethane sponge with deionized water or ethanol for 2-3 times, drying at 60 ℃, cutting the polyurethane sponge into strips (5cm x 1cm x 0.2cm), dipping the strips into the micro-nano liquid metal dispersion, taking out the micro-nano liquid metal dispersion, placing the micro-nano liquid metal dispersion in an oven at 65 ℃ for 30min, and uniformly distributing the liquid metal at the reversal frequency of 1 time/min.
(3) And (3) soaking the polyurethane sponge sample strip in the liquid metal dispersion liquid for 3 times to obtain a stretchable conductive composite material precursor based on the micro-nano liquid metal with the liquid metal volume fraction of 10%, and mechanically sintering under the pressure of 600N to fuse the micro-nano particles of the liquid metal together to form a liquid metal layer, so as to prepare the stretchable conductive composite material. The test method was the same as in example 1, and the test results are shown in Table 2.
Example 6:
the preparation method is the same as example 5, except that in the step (2), the cleaned polyurethane sponge sample (5cm x 1cm x 0.2cm) is placed in Tris-HCl buffer solution with dissolved dopamine for 24h (Tris hydrochloric acid buffer solution), the dopamine concentration is 0.25mol/ml, and the pH of the buffer solution is 8.5. And washing the modified sponge with deionized water and drying. The test method was the same as in example 1, and the test results are shown in Table 2.
Comparative example 3:
washing the polyurethane sponge with deionized water or ethanol for 2-3 times, drying, cutting into strips (5cm x 1cm x 0.2cm), fixing below the liquid level of the liquid metal, placing in a vacuum drying oven for 5min, wiping off the residual liquid metal on the surface of the sample strip, and controlling the filling volume fraction to be 10%. The test method was the same as in example 1, and the test results are shown in Table 2.
TABLE 2 comparison of the Performance of examples 5-6 with that of comparative example 3
| Mass loss Δ m/m0(％) | Conductivity (S/cm) | Delta R/R at 50% elongation0(％) | |
| Example 5 | 4 | 118 | 17 |
| Example 6 | 1.5 | 123 | 19 |
| Comparative example 3 | 70 | 103 | 31 |
As can be seen from the data in Table 2, the liquid metal leakage is reduced and the conductivity stability are good after the liquid metal stretchable conductive composite material substrate prepared by the method provided by the invention is subjected to surface modification by the polydopamine. Compared with the method of directly filling liquid metal in the matrix, the method can obviously reduce the leakage of the liquid metal in the composite material and maintain good conductivity and conductive stability.
Claims (10)
1. A stretchable conductive composite based on liquid metal comprises a liquid metal layer and an elastomer sponge; wherein, the liquid metal layer is distributed on the surface of the elastomer sponge framework.
2. The stretchable conductive composite of claim 1, characterized in that:
the volume percentage of the liquid metal layer is 0.5-15%, preferably 8-14%, calculated by the apparent volume of the elastomer sponge.
3. The stretchable conductive composite of claim 1, characterized in that:
the liquid metal is eutectic point alloy with the melting point lower than 25 ℃, and preferably one or two of gallium-indium alloy and gallium-indium-tin alloy; and/or the presence of a gas in the gas,
the porosity of the elastomer sponge is 45-95%, preferably 50-90%.
4. The stretchable conductive composite of claim 1, characterized in that:
the liquid metal layer is formed by sintering liquid metal micro-nano particles, and/or,
the elastomer sponge is polydopamine surface modified elastomer sponge, preferably one or more of polydopamine surface modified polydimethylsiloxane sponge, polyurethane sponge or latex sponge.
5. The method of preparing a stretchable conductive composite material based on a liquid metal according to claims 1 to 4, comprising:
preparing the liquid metal into liquid metal micro-nano particle dispersion liquid, dipping the elastomer sponge into the dispersion liquid, taking out the elastomer sponge/dispersion liquid compound, drying, and then performing pressure sintering or laser sintering to obtain the stretchable conductive composite material.
6. The method according to claim 5, wherein the method comprises the steps of:
step 1, adding the liquid metal into a dispersing agent, adding a sulfhydryl compound after ultrasonic crushing, and mixing to form a liquid metal micro-nano particle dispersion liquid;
step 2, placing the elastomer sponge in a buffer solution dissolved with dopamine, and fully performing immersion reaction at room temperature to obtain polydopamine-modified elastomer sponge;
step 3, dipping the modified elastomer sponge obtained in the step 2 into the liquid metal micro-nano particle dispersion liquid prepared in the step 1 at room temperature, fully dipping and drying to obtain the modified elastomer sponge coated with the liquid metal micro-nano particles;
and 4, performing laser sintering or pressure sintering on the modified elastomer sponge coated with the liquid metal micro-nano particles obtained in the step 3 to obtain the stretchable conductive composite material.
7. The production method according to claim 6,
in the step 1: the liquid metal is eutectic point alloy with the melting point lower than 25 ℃, and preferably one or two of gallium-indium alloy and gallium-indium-tin alloy; and/or the presence of a gas in the gas,
the dispersant is at least one of water and an organic solvent, wherein the organic solvent is at least one of ether, furan, ketone and alcohol, and preferably at least one of diethyl ether, acetone, ethanol, isopropanol and tetrahydrofuran; and/or the presence of a gas in the gas,
the concentration of the liquid metal in the dispersion liquid is 0.01-0.2 g/ml, preferably 0.02-0.15 g/ml; and/or the presence of a gas in the gas,
the mercapto compound is at least one of an organic compound containing mercapto and carboxyl, an organic compound containing mercapto and amino, and an organic compound containing mercapto and carbonyl; preferably at least one of thioglycolic acid, mercaptopropionic acid, 4-mercaptobutyric acid, 8-mercaptoheptanoic acid, 11-mercaptoundecanoic acid, mercaptoethylamine, 3-mercapto-1-propylamine, 1-mercapto-2-acetone, 4-mercapto-2-pentanone, and 3-mercapto-2-butanone; and/or the presence of a gas in the gas,
the concentration of the sulfhydryl compound in the dispersion liquid is 0.5-25 mM, preferably 0.5-20 mM; and/or the presence of a gas in the gas,
the ultrasonic crushing is carried out in a water bath at the temperature of 0-10 ℃ for 0.5-2 h; the power of ultrasonic crushing is preferably 1000-1500W, the preferred temperature is 0-5 ℃, and the preferred time is 0.5-1 h; and/or the presence of a gas in the gas,
the liquid metal micro-nano particles dispersed in the dispersing agent are obtained through ultrasonic crushing, and the average particle size is 20-1000 nm; and/or the presence of a gas in the gas,
the mixing to form a liquid metal particle dispersion comprises: carrying out ultrasonic treatment on the mixture containing the liquid metal micro-nano particles, the dispersing agent and the mercapto compound in a water bath at the temperature of 0-40 ℃ for 10-50 min to obtain a stable liquid metal micro-nano particle dispersion liquid; and/or the presence of a gas in the gas,
centrifuging the liquid metal micro-nano particle dispersion liquid subjected to ultrasonic treatment for 10-30 min, preferably 25-35 min at a centrifugation rate of 500-3500 r/min; and removing liquid from the liquid metal micro-nano particle dispersion liquid, adding the dispersing agent again, and carrying out ultrasonic treatment after repeated washing to obtain the stable liquid metal particle dispersion liquid.
8. The method of claim 6, wherein:
in the step 2: the elastomer sponge is polydopamine surface modified elastomer sponge, preferably one or more of polydopamine surface modified polydimethylsiloxane sponge, polyurethane sponge or latex sponge; and/or the presence of a gas in the gas,
before dipping, cleaning and drying the elastomer sponge by using water or ethanol, wherein the drying temperature is 50-80 ℃; and/or the presence of a gas in the gas,
the buffer solution is a tris (hydroxymethyl) aminomethane hydrochloric acid buffer aqueous solution, and the pH value of the buffer solution is 7.5-9; and/or the presence of a gas in the gas,
wherein the concentration of the dopamine in the buffer solution is 0.01-0.5 mol/ml, preferably 0.05-0.3 mol/ml; and/or the presence of a gas in the gas,
the dipping time is 1-32 hours.
9. The method of claim 6, wherein:
in the step 3: cutting the modified elastomer sponge into blocks, sheets or strips before dipping the liquid metal micro-nano particle dispersion liquid; and/or the presence of a gas in the gas,
taking out the modified elastomer sponge soaked in the dispersion liquid, and drying in an oven at the temperature of 60-100 ℃ for 10-30 min; preferably, the elastomer sponge impregnated with the dispersion is inverted at a frequency of 1/20 min to 1/1 min, preferably 1/15 min to 1/min, during drying; and/or the presence of a gas in the gas,
and repeating the steps of drying the soaked modified elastomer sponge for 1-40 times.
10. The method of claim 6, wherein:
in the step 4: the sponge is placed at 5-10J/cm2The sintering is carried out under laser, and the preferred range is 7-9J/cm2Sintering under laser; or
And (3) mechanically sintering at the temperature of 10-50 ℃ and the pressure of 100-1000N, preferably at the temperature of 10-40 ℃ and the pressure of 500-1000N.
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