CN115881340A - Flexible stretchable electrode with high conductive stability and preparation method thereof - Google Patents
Flexible stretchable electrode with high conductive stability and preparation method thereof Download PDFInfo
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Abstract
The invention provides a flexible stretchable electrode with high conductive stability and a preparation method thereof. The flexible stretchable electrode includes a flexible stretchable insulating substrate and a flexible stretchable conductor on a surface thereof; the flexible stretchable conductor comprises a stretchable elastic insulator, micro-nano-scale conductive particles and conductive nanowires, wherein the mass ratio of the conductive particles to the elastic insulator is 1. The elongation of the flexible stretchable conductor can reach more than 30%, the resistance change rate of the conductor in the stretching process is small, the resistance change rate is less than 1.5 when the elongation reaches 5%, the resistance change rate is less than 3 when the elongation reaches 10%, and the resistance change rate is less than 20 when the elongation reaches 20%, so that the flexible stretchable conductor has high conductive stability and has a good application prospect in flexible electronic devices.
Description
Technical Field
The invention relates to the technical field of flexible electronics, in particular to a flexible stretchable electrode with high conductive stability and a preparation method thereof.
Background
In recent years, with the development of the internet of things and wearable electronic technology, flexible electronic devices have become the mainstream trend of the development of future electronic devices.
Elasticity is one of flexibility, which means that it can deform under the action of an external force and has a certain shape recovery capability when the external force is removed. The stretchable electronic device is one of elastic electronic devices, can deform under the action of external force to increase the length, has certain shape recovery capability when the external force is removed, and has wide application prospect in wearable electronic equipment.
Stretchable conductors are key components in stretchable electronic devices, having both mechanical stretchability and electrical conductivity. However, in practical applications, the stretchability and the conductivity of the material are difficult to be considered. For example, metal generally has excellent electrical conductivity, but its mechanical elongation is poor in stretchability; soft materials such as elastomers or rubbers generally have good stretchability, but have poor conductivity.
In addition, in flexible electronic devices, in order to maintain the conductive stability, it is desirable that the rate of change in resistance of the stretchable conductor during stretching be as small as possible. However, the rate of change in resistance of the conventional stretchable conductor increases sharply as the elongation rate increases. For example, the document Applied Physics Letters 82, 2404-2406 (2003) reports that the rate of change of resistance of an Au elastic electrode material reaches 700 when the material is elongated by 20%; the document Applied Physics Letters 98, 153110 (2011) reports that when silver electrodes are printed directly on flat PDMS, the rate of change of resistance of the conductor exceeds 10 when the conductor is elongated less than 2%.
Disclosure of Invention
In view of the above technical problems, the present invention aims to provide a flexible stretchable electrode having good conductive stability during stretching.
In order to achieve the technical purpose, after a large number of long-term experimental researches, the inventor finds that when the components of the conductor comprise a stretchable elastic insulator, conductive particles and conductive nanowires, wherein the conductive particles and the conductive nanowires are uniformly dispersed in the stretchable elastic insulator to form a conductive network, the mass ratio of the conductive particles to the elastic insulator is controlled to be 1; when the elongation reaches 20%, the resistance change rate is less than 20, even less than 6; the resistance change rate is less than 75, even less than 20 when the elongation reaches 30%.
In the present invention, the original length of the stretchable conductor before stretching is L, and the resistance of the conductor in the original length condition is R 0 Length after drawing is L ’ The resistance of the conductor after stretching is R ’ Conductor elongation epsilon = (L-L) ’ ) < L > 100%, rate of change of resistance = [ Delta ] R/R 0 ＝(R ’ -R 0 )/R 0 。
Namely, the technical scheme of the invention is as follows: a flexible, stretchable electrode having high conductive stability, characterized by: the flexible stretchable conductor comprises a flexible stretchable insulating substrate and a flexible stretchable conductor positioned on the surface of the flexible stretchable insulating substrate;
the flexible stretchable conductor comprises a stretchable elastic insulator, conductive particles and conductive nanowires, wherein the conductive particles and the conductive nanowires are uniformly dispersed in the elastic insulator; the particle size of the conductive particles is micron-scale or nano-scale;
the ratio of the mass of the conductive particles to the mass of the elastic insulator is 1;
the ratio of the mass of the conductive nanowire to the mass of the elastic insulator is from 2.
The flexible and stretchable insulating substrate is formed by compounding fabric and a high polymer film. As one implementation, the flexible stretchable substrate is made by hot-pressing a polymer adhesive film on a fabric. Preferably, the hot pressing temperature is 140 to 170 ℃. The fabric material is not limited and comprises one or more of cotton, hemp, wool, silk, wool fabric and fiber material. The polymer film material is not limited, and comprises one or more of silica gel, polydimethylsiloxane, polyurethane, rubber, hydrogel, TPE, ecoflex and POE (polyolefin elastomer) composite materials and composite materials taking the silica gel, the polydimethylsiloxane, the polyurethane, the rubber, the hydrogel, the TPE, the Ecoflex and the POE as substrates and containing doped materials.
Preferably, the conductive particles have a particle size of 10nm to 100 μm.
The material of the conductive particles is not limited, and includes metals and alloys, such as one or more of silver, copper, nickel, aluminum, silver-coated copper, silver-coated nickel, and the like, and carbon black.
Preferably, the length of the conductive nanowire is 1-30 μm, and the radial dimension is 1-30nm.
Preferably, the length of the conductive nanowire is greater than the particle size of the conductive particle.
The material of the conductive nanowire is not limited, and comprises one or more materials of a nano gold wire, a nano silver wire, a nano copper wire, a carbon nanotube and a conductive carbon fiber.
The stretchable elastic insulator has insulation properties and stretchable elasticity. The stretchable elastic insulator is not limited and comprises one or more of silicone rubber, polydimethylsiloxane, polyurethane (PU), rubber, hydrogel, SEBS, ecoflex and polyolefin elastomer (POE) and a composite material which takes the silicone rubber, the polydimethylsiloxane, the Polyurethane (PU), the rubber, the hydrogel, the SEBS, the Ecoflex and the POE as matrix materials and contains doped materials.
The invention also provides a method for preparing the flexible stretchable electrode, which comprises the following steps:
coating and printing the conductive slurry on a flexible stretchable substrate, and solidifying after the solvent is volatilized;
the preparation method of the conductive paste comprises the following steps:
adding a diluting solvent into the raw materials to dilute uniformly to obtain a diluent; the starting material is a polymeric monomer that polymerizes to form a stretchable, elastic insulator;
adding conductive nanowires and conductive particles into the diluent, and uniformly dispersing to obtain a mixed solution;
adding curing agent into the mixed solution to make the polymer monomer generate polymerization reaction, then coating and printing the mixture on a flexible and stretchable insulating substrate, and curing and forming after volatilizing the diluent.
The present invention also provides another method of preparing the flexible stretchable electrode, comprising the steps of:
adding a diluting solvent into the raw materials to dilute uniformly to obtain a diluent; the raw material is a polymer which is a stretchable elastic insulator;
adding conductive nanowires and conductive particles into the diluent, and uniformly dispersing to obtain a mixed solution;
and coating and printing the mixed solution on a flexible and stretchable insulating substrate, and curing and forming after the diluent is volatilized.
In the two preparation methods, the diluent contains the raw materials by weight percent of 10-40%.
In the two preparation methods, in the process of adding the conductive nanowires and the conductive particles into the diluent and uniformly dispersing to obtain the mixed solution, preferably, the conductive nanowires are firstly added into the diluent and uniformly dispersed, and then the conductive particles are added and uniformly dispersed. Preferably, ultrasonic dispersion is adopted, and the dispersion time is 3-120 min.
In the above two preparation methods, the diluent is volatilized by heating at 40-120 deg.C.
In the above two production methods, preferably, the curing and molding are followed by high-temperature heat treatment, preferably at a temperature of 150 to 180 ℃.
In the two preparation methods, the diluting solvent is not limited, and comprises one or more of N-hexane, N-heptane, cyclohexane, N-dimethylformamide, N-dimethylacetamide, benzene, toluene, dichloromethane, trichloromethane and the like.
In the above two manufacturing methods, preferably, a template is used when the mixed solution is coated or printed on the flexible stretchable insulating substrate, and the patterned conductor is obtained by curing and molding after the diluent is volatilized.
The invention combines a flexible stretchable insulating substrate and a flexible stretchable conductor to obtain a flexible stretchable electrode, wherein the flexible stretchable conductor is formed by adding conductive particles and conductive nanowires into a stretchable elastic insulator, so that the conductive particles are uniformly dispersed in the stretchable elastic insulator to form a conductive main body, and the conductive nanowires are uniformly dispersed in the stretchable elastic insulator to bridge the conductive particles, thereby forming a conductive network, and the conductivity and the stretchability of the material are realized by combining the stretchable elastic insulator. In addition, the invention realizes that the elongation of the conductor reaches more than 30 percent and simultaneously ensures that the resistance change rate of the conductor in the stretching process is smaller by controlling the contents of the conductive particles and the conductive nanowires, and the method comprises the following specific steps:
the resistance change rate is less than 1.5 and even less than 1.0 when the elongation reaches 5 percent;
when the elongation reaches 10%, the resistance change rate is less than 3, even less than 2;
when the elongation reaches 20%, the resistance change rate is less than 20, even less than 6;
the resistance change rate is less than 75 and even less than 20 when the elongation reaches 30 percent.
Especially when the elastic insulator is silicone:
when the elongation reaches 5%, the resistance change rate is less than 1.0, even less than 0.6;
the resistance change rate is less than 1.0 and even less than 0.5 when the elongation reaches 10 percent;
the resistance change rate is less than 0.5 and even less than 0.3 when the elongation reaches 20 percent;
the resistance change rate is less than 0.5, even less than 0.3 when the elongation reaches 30%.
Therefore, compared with the prior art, the flexible stretchable electrode greatly improves the conductive stability and has good application prospect in flexible electronic devices.
Drawings
FIG. 1 is a graph of the rate of change of resistance with elongation of stretchable conductors in examples 1-3 of the present invention.
FIG. 2 is a graph of the rate of change of resistance with elongation of the stretchable conductor in examples 1, 4 and 5 of the present invention.
FIG. 3 is a graph showing the rate of change in resistance with the stretching ratio of the stretchable conductor in comparative example 1.
Fig. 4 is a partially enlarged view of fig. 3.
FIG. 5 is a graph showing the rate of change in resistance with the stretching ratio of the stretchable conductor in comparative example 2.
FIG. 6 is a graph of the rate of change of resistance with the rate of stretching of the stretchable conductor in example 6.
Detailed Description
The present invention is further described in detail below with reference to the drawings and examples, which are intended to facilitate the understanding of the present invention without limiting it in any way.
Example 1:
in the present embodiment, the flexible stretchable electrode is composed of a flexible stretchable insulating substrate and a flexible stretchable conductor on a surface of the flexible stretchable insulating substrate. Flexible stretchable insulating substrate made of spandex fabric and
the TPU film is compounded and prepared by hot-pressing a TPU thermosol film on a spandex fabric.
The flexible stretchable conductor is composed of 15 parts by mass of PU, 0.75 part by mass of multi-walled carbon nanotubes and 30 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU. The particle diameter of the silver powder is 3-5 μm, and the purity is 99.9%. The diameter of the multi-wall carbon nano tube is 10-20nm, and the length of the multi-wall carbon nano tube is 10-30 mu m.
The preparation method of the flexible stretchable electrode comprises the following steps:
(1) Weighing 15 parts by mass of PU particles, adding the PU particles into a flat-bottomed flask filled with 85 parts of N, N-dimethylformamide reagent, and magnetically stirring for 6 hours to completely dissolve the PU particles without solid residues;
(2) Adding 0.75 part by mass of carbon nanotube resin dispersant into the completely dissolved PU solution obtained in the step (1), and magnetically stirring for 60min to completely dissolve the PU solution; then, 0.75 part by mass of multi-walled carbon nanotubes are added, magnetic stirring is carried out for 10min, then the mixture is placed in an ultrasonic cleaning machine for ultrasonic treatment for 30min, the multi-walled carbon nanotubes are dispersed, and the whole process is carried out by sealing with a preservative film;
(3) Weighing 30 parts by mass of silver powder, adding the silver powder into the PU solution of the dispersed multi-wall carbon nano-tube obtained in the step (2), sealing, magnetically stirring at a high speed for 90min, then placing the mixture into a vacuum oven, vacuumizing and defoaming for 10min, taking out and sealing for later use;
(4) Cutting a spandex fabric with the size of 20mm multiplied by 20mm, cutting a TPU hot melt adhesive film with the same size, hot-pressing the polyurethane fabric on a hot press at 160 ℃ for 30s, taking out the polyurethane fabric, and tearing off release paper;
(5) Printing the conductive paste prepared in the step (3) on one surface of a flexible substrate pressed with a TPU thermosol film through a stainless steel template, and then drying in a forced air drying oven at 40 ℃ to remove a solvent to obtain a template-shaped electrode; and (3) placing the electrode array subjected to solvent removal in an oven for heat treatment at 150 ℃ for 30min to obtain the flexible stretchable electrode.
In order to test the conductivity and tensile property of the flexible stretchable conductor, a hollow structure with the size of 35mm multiplied by 15mm multiplied by 0.5mm is cut out from a TPE sheet with the thickness of 0.5mm, the TPE sheet is pasted on a glass sheet to be used as a curing forming die, the mixed solution obtained in the step (3) after defoaming is poured into the forming die, the TPE sheet is placed in an oven to be heated to 40 ℃, a diluent solvent N, N-dimethylformamide is volatilized after heating for 120min, a cured composite PU film is obtained, then the cured composite PU film is placed in the oven, and the composite PU film is peeled from the glass sheet in a mechanical peeling mode after heat treatment is carried out for 30min at 150 ℃, so that the stretchable conductor is obtained.
Example 2:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: the flexible stretchable conductor is composed of 15 parts by mass of PU, 0.75 part by mass of multi-walled carbon nanotubes and 22.5 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The method of manufacturing the flexible stretchable electrode was substantially the same as that of example 1 except that 30 parts by mass of the silver powder particles in example 1 were replaced with 22.5 parts by mass of the silver powder particles.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (3) in the same manner as in example 1, except that 30 parts by mass of the silver powder particles in example 1 were replaced with 22.5 parts by mass of the silver powder particles.
Example 3:
in this embodiment, the structure and composition of the flexible stretchable electrode are substantially the same as those of the flexible stretchable electrode in embodiment 1, except that: the flexible stretchable conductor is composed of 15 parts by mass of PU, 0.75 part by mass of multi-walled carbon nanotubes and 15 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The flexible stretchable electrode was prepared in substantially the same manner as in example 1, except that 30 parts by mass of the silver powder particles in example 1 were replaced with 15 parts by mass of the silver powder particles.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in the step (3) in the same manner as in example 1, except that 30 parts by mass of the silver powder particles in example 1 were replaced with 15 parts by mass of the silver powder particles.
The conductive properties and tensile properties of the stretchable conductors obtained in examples 1 to 3 were measured, and the results of the tests are shown in FIG. 1, which show that these conductors have good stretchability, the elongation can reach 30% or more, and the rate of change in resistance is as follows:
it can be seen that, when the mass ratio of the carbon nanotube to the PU is 0.05, and the mass ratio of the ag powder to the PU is in the range of 1 to 1, the specific characteristics are as follows:
(1) The resistance change rate is less than 1.5 when the elongation rate is 5%, less than 3 when the elongation rate is 10%, less than 20 when the elongation rate is 20%, less than 35 when the elongation rate is 25%, and less than 75 when the elongation rate is 30%;
(2) The resistance change rate decreases with the increase of the mass of the Ag powder, and particularly when the mass ratio of the Ag powder to PU is 1.5 or more, the resistance change rate decreases significantly, the resistance change rate is less than 1.0 at an elongation of 5%, less than 2 at an elongation of 10%, less than 6 at an elongation of 20%, less than or equal to 10 at an elongation of 25%, and less than or equal to 20 at an elongation of 30%.
Example 4:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: the flexible stretchable conductor is composed of 15 parts by mass of PU, 0.3 part by mass of multi-walled carbon nanotubes and 30 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The flexible stretchable electrode was prepared in substantially the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 0.3 parts by mass of the multi-walled carbon nanotubes.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (3) in the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 0.3 parts by mass of the multi-walled carbon nanotubes.
Example 5:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: the flexible stretchable conductor is composed of 15 parts by mass of PU, 1.5 parts by mass of multi-walled carbon nanotubes and 30 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The flexible stretchable electrode was prepared in substantially the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 1.5 parts by mass of the multi-walled carbon nanotubes.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (3) in the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 1.5 parts by mass of the multi-walled carbon nanotubes.
The conductive properties and tensile properties of the stretchable conductors obtained in the above examples 1, 4 and 5 were measured, and the results of the tests are shown in fig. 2, which shows that these conductors have good stretchability, the elongation can reach 30% or more, and the rate of change in resistance is as follows:
it can be seen that, when the mass ratio of the Ag powder to the PU is 2:1-0.1, the specific characteristics are as follows:
(1) The resistance change rate is less than 0.8 at an elongation of 5%, less than 1.5 at an elongation of 10%, less than 5 at an elongation of 20%, less than 9 at an elongation of 25%, and less than 16 at an elongation of 30%.
(2) With the increase of the added mass of the carbon nanotubes, the resistance change rate of the conductor becomes smaller, mainly due to the addition of the carbon nanotubes and the increase of the conductive network structure, so that the resistance stability is increased during stretching. Especially when the mass ratio of the carbon nanotubes to the PU is greater than or equal to 0.05:1, a resistance change rate remarkably decreased, the resistance change rate was 0.6 or less at an elongation of 5%, the resistance change rate was 1.0 or less at an elongation of 10%, the resistance change rate was 4 or less at an elongation of 20%, the resistance change rate was 7.0 or less at an elongation of 25%, and the resistance change rate was 12.5 or less at an elongation of 30%.
Comparative example 1:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: in the flexible stretchable conductor, the stretchable conductor is composed of 15 parts by mass of PU, 0 part by mass of multi-walled carbon nanotubes and 30 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The method for preparing the flexible stretchable electrode was substantially the same as that of example 1, except that step (3) was performed after step (1) was completed, without including step (2).
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (3) in the same manner as in example 1, except that step (3) was performed after completion of step (1) without including step (2).
The conductive properties and tensile properties of the stretchable conductor prepared in this comparative example 1 were measured, and the results of the tests, as shown in fig. 3 and 4, showed that the tensile properties and conductive stability of the conductor were poor without the addition of multi-walled carbon nanotubes, the resistance change rate exceeded 800 at an elongation of 18%, and reached 10 already at an elongation of 10%.
Comparative example 2:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: the conductor consists of 15 parts by mass of PU, 0.15 part by mass of multi-walled carbon nanotubes and 30 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The flexible stretchable electrode was prepared in substantially the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 0.15 parts by mass of the multi-walled carbon nanotubes.
In order to test the conductivity and tensile properties of the flexible stretchable conductor in the same manner as in example 1, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (3) in substantially the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 0.15 parts by mass of the multi-walled carbon nanotubes.
The conductive properties and tensile properties of the stretchable conductor obtained in this comparative example 2 were measured, and as shown in fig. 5, the tensile properties and conductive stability of the conductor were improved as compared to those of comparative example 1, but the resistance change rate exceeded 60 when the elongation was 25%; when the elongation is 30%, the resistance change rate exceeds 350.
Comparative example 3:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: the conductor is composed of 15 parts by mass of PU, 2.25 parts by mass of multi-walled carbon nanotubes and 30 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The flexible stretchable electrode was prepared in substantially the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 2.25 parts by mass of the multi-walled carbon nanotubes.
In order to test the conductivity and tensile properties of the flexible stretchable conductor in the same manner as in example 1, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (3) in substantially the same manner as in example 1, except that 0.75 parts by mass of the multi-walled carbon nanotubes in example 1 were replaced with 2.25 parts by mass of the multi-walled carbon nanotubes. The preparation results show that the film forming property is poor, the surface is cracked, the tensile property is very poor, and the film is easy to break.
Comparative example 4:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in embodiment 1, except that: the conductor is composed of 15 parts by mass of PU, 0.75 part by mass of multi-walled carbon nanotubes and 9 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and silver powder are uniformly dispersed in the PU.
The flexible stretchable electrode was prepared in substantially the same manner as in example 1, except that 30 parts by mass of the silver powder particles in example 1 were replaced with 9 parts by mass of the silver powder particles.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in the step (3) in the same manner as in example 1, except that 30 parts by mass of the silver powder particles in example 1 were replaced with 9 parts by mass of the silver powder particles.
The conductive properties of the conductors prepared in this comparative example were measured and showed poor conductivity with a surface resistance >1M Ω.
Comparative example 5:
in this embodiment, the structure and composition of the flexible stretchable electrode are substantially the same as those of the flexible stretchable electrode in embodiment 1, except that: the conductor is composed of 15 parts by mass of PU, 0.75 part by mass of multi-walled carbon nanotubes and 33 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the PU.
The method of manufacturing the flexible stretchable electrode was substantially the same as that of example 1 except that 30 parts by mass of the silver powder particles in example 1 were replaced with 33 parts by mass of the silver powder particles.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in the step (3) in the same manner as in example 1, except that 30 parts by mass of the silver powder particles in example 1 were replaced with 33 parts by mass of the silver powder particles. The results show that the mixed solution obtained in step (4) has a high viscosity, a poor forming effect and a serious aggregation of Ag powder.
Example 6:
in the present embodiment, the flexible stretchable electrode is composed of a flexible stretchable insulating substrate and a flexible stretchable conductor on a surface of the flexible stretchable insulating substrate. The flexible stretchable insulating substrate is formed by compounding a spandex fabric and a TPU film and is prepared by hot-pressing a TPU thermosol film on the spandex fabric.
The stretchable conductor is composed of 100 parts by mass of silica gel, 5 parts by mass of multi-walled carbon nanotubes and 200 parts by mass of silver powder particles, and the multi-walled carbon nanotubes and the silver powder are uniformly dispersed in the silica gel. The silver powder has a particle size of 3-5 μm and a purity of 99.9%. The diameter of the multi-wall carbon nano tube is 10-20nm, and the length of the multi-wall carbon nano tube is 10-30 mu m.
The preparation method of the flexible stretchable electrode is shown in figure 1 and comprises the following steps:
(1) Weighing 100 parts of silica gel, adding 200 parts of n-heptane solvent for dilution, sealing with a preservative film, and magnetically stirring for 30min to completely dilute the silica gel;
(2) Adding 5 parts of multi-walled carbon nanotubes into the completely diluted silica gel solution obtained in the step (1), magnetically stirring for 10min, then placing the solution in an ultrasonic cleaning machine for ultrasonic treatment for 30min, dispersing the multi-walled carbon nanotubes, and sealing the whole process by using a preservative film;
(3) Weighing 200 parts of silver powder, adding the silver powder into the silica gel solution of the dispersed multi-walled carbon nano-tube obtained in the step (2), sealing, and magnetically stirring at a high speed for 90min;
(4) Weighing 10 parts of curing agent, adding the curing agent into the mixed solution obtained in the step (3), sealing the preservative film, magnetically stirring for 10min, then putting the mixture into a vacuum oven, vacuumizing and defoaming for 10min, taking out the mixture, and sealing the mixture for later use;
(5) Cutting a spandex fabric with the size of 20mm multiplied by 20mm, cutting a TPU hot melt adhesive film with the same size, hot-pressing the polyurethane fabric on a hot press at 160 ℃ for 30s, taking out the polyurethane fabric, and tearing off release paper;
(6) Printing the defoamed mixed solution obtained in the step (4) on one surface of a flexible substrate pressed with a TPU thermosol film through a stainless steel template, and then drying in a forced air drying oven at 40 ℃ to remove a solvent to obtain a template-shaped electrode; and (3) placing the electrode array subjected to solvent removal in an oven for heat treatment at 150 ℃ for 30min to obtain the flexible stretchable electrode.
In order to test the conductivity and tensile property of the flexible stretchable conductor, a hollow structure with the size of 35mm multiplied by 15mm multiplied by 0.5mm is cut out from a TPE sheet with the thickness of 0.5mm, the TPE sheet is pasted on a glass sheet and used as a silica gel curing forming die, the obtained mixed solution after defoaming obtained in the step (4) is poured into the forming die, the mixed solution is placed into an oven and heated to 60 ℃, the mixed solution is heated for 15min to volatilize a diluting solvent n-heptane, then the mixed solution is heated to 80 ℃ and cured for 120min to obtain a cured composite silica gel film, then the cured composite silica gel film is placed into the oven, and the composite silica gel film is peeled from the glass sheet in a mechanical glass mode after heat treatment at 150 ℃ for 30min to obtain the stretchable conductor.
The tensile properties and conductive properties of the stretchable conductor prepared as described above were measured, and the test results are shown in fig. 6, showing that the conductor has good stretchability, can achieve an elongation of 30% or more, and has good conductive stability during stretching, a resistance change rate of only about 0.55 when the elongation reaches 5%, a resistance change rate of only about 0.45 when the elongation reaches 10%, a resistance change rate of only about 0.27 when the elongation reaches 20%, and a resistance change rate of only about 0.23 when the elongation reaches 30%.
Comparative example 6:
in this embodiment, the flexible stretchable electrode has substantially the same structure and composition as those of the flexible stretchable electrode of embodiment 6, except that: the conductor is composed of 100 parts by mass of silica gel and 1 part by mass of multi-walled carbon nanotubes, and the multi-walled carbon nanotubes are uniformly dispersed in the silica gel.
The flexible stretchable electrode was produced in substantially the same manner as in example 6, except that 5 parts by mass of the multi-walled carbon nanotubes in example 6 were replaced with 1 part by mass of the multi-walled carbon nanotubes, and step (3) was not included.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (4) in the same manner as in example 6, except that 5 parts by mass of the multi-walled carbon nanotube in example 6 was replaced with 1 part by mass of the multi-walled carbon nanotube.
The results showed that the conductor had poor conductivity and had a surface resistance >1 M.OMEGA..
Comparative example 7:
in this example, the flexible stretchable electrode has substantially the same structure and composition as the flexible stretchable electrode in example 6, except that: the conductor is composed of 100 parts by mass of silica gel and 15 parts by mass of multi-walled carbon nanotubes, and the multi-walled carbon nanotubes are uniformly dispersed in the silica gel.
The flexible stretchable electrode was prepared in substantially the same manner as in example 6, except that 5 parts by mass of the multi-walled carbon nanotubes in example 6 were replaced with 15 parts by mass of the multi-walled carbon nanotubes, and step (3) was not included.
In order to test the conductivity and tensile properties of the flexible stretchable conductor, a stretchable conductor was prepared using the defoamed mixed solution obtained in step (4) in the same manner as in example 6, except that 5 parts by mass of the multi-walled carbon nanotubes in example 6 were replaced with 15 parts by mass of the multi-walled carbon nanotubes, and step (3) was not included.
The results showed that the conductor had poor film-forming properties and had surface cracks.
The embodiments described above are intended to illustrate the technical solutions of the present invention in detail, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modification, supplement or similar substitution made within the scope of the principle of the present invention should be included in the protection scope of the present invention.
Claims (14)
1. A flexible, stretchable electrode having high conductive stability, characterized by: the flexible stretchable conductor comprises a flexible stretchable insulating substrate and a flexible stretchable conductor positioned on the surface of the flexible stretchable insulating substrate;
the flexible stretchable conductor comprises a stretchable elastic insulator, conductive particles and conductive nanowires, wherein the conductive particles and the conductive nanowires are uniformly dispersed in the elastic insulator;
the particle size of the conductive particles is micron-scale or nano-scale;
the mass ratio of the conductive particles to the elastic insulator is 1;
the mass ratio of the conductive nanowire to the elastic insulator is 2.
2. The flexible stretchable electrode of claim 1 further characterized by: the flexible stretchable insulating substrate is formed by compounding a fabric and a high polymer film;
preferably, the flexible and stretchable insulating substrate is formed by hot-pressing a high polymer film on a fabric;
preferably, the hot pressing temperature is 140-170 ℃;
preferably, the fabric comprises one or more of cotton, hemp, wool, silk, wool fabric and fiber materials;
preferably, the polymer film material comprises one or more of silica gel, polydimethylsiloxane, polyurethane, rubber, hydrogel, TPE, ecoflex and POE (polyolefin elastomer) composite materials and composite materials taking the silica gel, the polydimethylsiloxane, the polyurethane, the rubber, the hydrogel, the TPE, the Ecoflex and the POE as substrates and containing doped materials.
3. The flexible stretchable electrode of claim 1 further characterized by: the mass ratio of the conductive particles to the elastic insulator is 1.5.
4. The flexible stretchable electrode of claim 1 further characterized by: the mass ratio of the conductive nanowire to the elastic insulator is 5.
5. The flexible stretchable electrode of claim 1 further characterized by: the particle size of the conductive particles is 10nm-100 μm.
6. The flexible stretchable electrode of claim 1 further characterized by: the conductive particles comprise a metal and carbon black;
the metal comprises one or more of silver, copper, nickel, aluminum, silver-coated copper, silver-coated nickel and silver nanowires.
7. The flexible stretchable electrode of claim 1 further characterized by: the length of the conductive nanowire is 1-30 mu m, and the radial dimension is 1-30nm.
8. The flexible stretchable electrode of claim 1 further characterized by: the length of the conductive nanowire is greater than the particle size of the conductive particle.
9. The flexible stretchable electrode of claim 1, wherein: the stretchable elastic insulator comprises one or more of silica gel, polydimethylsiloxane, polyurethane, rubber, hydrogel, SEBS, ecoflex and POE (polyolefin elastomer) and a composite material which takes the silica gel, the polydimethylsiloxane, the polyurethane, the rubber, the hydrogel, the SEBS, the Ecoflex and the POE as matrix materials and contains doped materials.
10. The flexible stretchable electrode of claim 1 further characterized by:
a resistance change rate of less than 1.5, preferably less than 1.0, at an elongation of 5%;
the rate of change of resistance of the flexible stretchable conductor up to 10% is less than 3, preferably less than 2;
a rate of change of resistance of the flexible stretchable conductor at 20% elongation of less than 20, preferably less than 6;
the flexible stretchable conductor has a resistance change rate of less than 75, preferably less than 20 at an elongation of 30%.
11. The stretchable conductor of claim 1, wherein: when the elastic insulator is made of silicon rubber,
a resistance change rate of less than 1.0, preferably less than 0.6, at an elongation of 5%;
a rate of change of resistance of the flexible stretchable conductor to 10% is less than 1.0, preferably less than 0.5;
a rate of change of resistance of the flexible stretchable conductor at 20% elongation of less than 0.5, preferably to less than 0.3;
the flexible stretchable conductor has a resistance change rate of less than 0.5, preferably less than 0.3 at an elongation of 30%.
12. A method of manufacturing a flexible stretchable electrode according to any one of claims 1 to 11 characterized by: the method comprises the following steps:
adding a diluting solvent into the raw materials to dilute uniformly to obtain a diluent; the starting material is a polymeric monomer that polymerizes to form a stretchable, elastic insulator;
adding conductive nanowires and conductive particles into the diluent, and uniformly dispersing to obtain a mixed solution;
adding a curing agent into the mixed solution to enable polymer monomers in the mixed solution to generate polymerization reaction, then coating and printing the mixture on a flexible and stretchable insulating substrate, and curing and molding after volatilizing a diluent in the mixture;
or, the method comprises the following steps:
adding a diluting solvent into the raw materials to dilute uniformly to obtain a diluent; the raw material is a polymer, namely a stretchable elastic insulator;
adding conductive nanowires and conductive particles into the diluent, and uniformly dispersing to obtain a mixed solution;
the mixed liquid is coated and printed on a flexible and stretchable insulating substrate, and the diluent is volatilized and then cured and molded.
13. The method of preparing a flexible stretchable electrode according to claim 12, characterized by: in the diluent, the mass percentage of the raw materials is 10-40%.
14. The method of preparing a flexible stretchable electrode according to claim 12, wherein: in the process of adding the conductive nanowires and the conductive particles into the diluent and uniformly dispersing to obtain a mixed solution, preferably, the conductive nanowires are added into the diluent and uniformly dispersed, and then the conductive particles are added and uniformly dispersed;
preferably, the diluent is volatilized by heating at 40-120 ℃;
preferably, high-temperature heat treatment is carried out after curing and forming, and the heat treatment temperature is preferably 150-180 ℃;
preferably, the diluting solvent comprises one or more of N-hexane, N-heptane, cyclohexane, N-dimethylformamide, N-dimethylacetamide, benzene, toluene, dichloromethane and chloroform.
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| CN117586671A (en) * | 2024-01-18 | 2024-02-23 | 之江实验室 | Conductive ink for preparing stretchable conductor, preparation method of conductive ink and stretchable conductor |
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