KR102102185B1 - Conducting polymer composite with high strechability - Google Patents

Abstract

According to one aspect of the invention, the conductive polymer composite region including the electrical conductor particles; And it is connected to at least a portion of the conductive polymer composite region, a conductive polymer composite having high elasticity is provided that includes a capping region that does not include the electrical conductor particles. According to an embodiment of the present invention, the conductive polymer composite, a matrix made of a polymer material having self-healing ability; And a plurality of electrically conductive clusters distributed in the matrix. According to an embodiment of the present invention, the electrical conductor cluster includes: first electrical conductor particles; And the same material as the first electroconductor particles, and may include a plurality of second electroconductor particles distributed around the first electroconductor particles and having a smaller size than the first electroconductor particles. .

Description

Conductive polymer composite with high strechability

The present invention relates to a conductive polymer composite having excellent elasticity, improved electrical conductivity properties by deformation, and further exhibiting self-healing properties, and a method for manufacturing the same.

Recently, a polymer material that is human-friendly and has excellent elasticity has been used in wearable electroinc devices applied to biomedicine, robots, and flexible devices. The high elastic polymer material can stably transmit power and data between the electronic device and the human body, and can be applied to an interconnector having mechanical elasticity. The interconnects should not show any deterioration in power and data transmission capability even if significant deformation occurs, e.g., rapid stretching. Additionally, even if a part of the interconnect is damaged or even cut, the value of utilization becomes higher if it can be recovered by self-healability.

 However, it is very difficult to simultaneously realize high elasticity, high conductivity, and excellent self-healing ability. Current wearable human-robot interfaces cannot support long-term interactions between humans and machines due to the lack of flexible interconnects that enable self-healing to enable feedback communication even after severe damage. In order to improve the self-healing performance of the stretchable electrical conductor, a technique is known in which micro-capsules made of monomers and catalysts are embedded to heal broken cracks. However, this technique has a problem in that it is possible to heal only once for a crack in an area where a microcapsule is located. As another method, a technique in which a portion where a crack has occurred is irradiated with ultraviolet rays (UV) from outside or applied heat. Recently, a method of forming an eGaIn (eutectic Ga-In) liquid metal alloy layer on a polymer substrate having self-healing ability has also been proposed. Such a structure exhibits high elasticity and excellent self-healing ability, but has a problem that it is difficult to apply liquid metal to a general electronic device.

The present invention is to solve such a conventional problem, and has an object to provide a conductive polymer composite that has high elasticity and electrical conductivity and does not deteriorate electrical conductivity even if significant deformation occurs. In addition, another object of the present invention is to provide a conductive polymer composite in which recovery occurs due to excellent self-healing ability even when damage occurs. However, these problems are exemplary, and the scope of the present invention is not limited thereby.

According to one aspect of the invention, the conductive polymer composite region including the electrical conductor particles; And it is connected to at least a portion of the conductive polymer composite region, a conductive polymer composite having high elasticity is provided that includes a capping region that does not include the electrical conductor particles.

According to an embodiment of the present invention, the conductive polymer composite, a matrix made of a polymer material having self-healing ability; And a plurality of electrically conductive clusters distributed in the matrix.

According to an embodiment of the present invention, the electrical conductor cluster includes: first electrical conductor particles; And the same material as the first electrical conductor particles, and may include a plurality of second electrical conductor particles that are distributed and distributed around the first electrical conductor particles and have a smaller size than the first electrical conductor particles. .

According to an embodiment of the present invention, the capping region may include a polymer having self-healing ability.

According to an embodiment of the present invention, the conductive polymer composite and the capping region may be connected by self-bonding.

According to an embodiment of the present invention, when the conductive polymer composite is maintained for a predetermined time in a state deformed by an external force, the electrical conductivity may be increased.

According to an embodiment of the present invention, as the conductive polymer composite is deformed by an external force, a rearrangement step in which spaced electrical conductor clusters are connected to each other may be performed.

According to an embodiment of the present invention, when the conductive polymer composite is maintained for a predetermined time in a state deformed by an external force, the spaced electrical conductor clusters may be connected to each other and rearranged.

According to an embodiment of the present invention, as the conductive polymer composite is maintained for a predetermined time in a state deformed by an external force, relaxation of stress may occur.

According to an embodiment of the present invention, the source of the second electrical conductor production may be the first electrical conductor.

According to an embodiment of the present invention, the polymer material having self-healing ability is polydimethylsiloxane (PDMS), polyethyleneoxide (PEO), Perfluoropolyether (PFPE), polybutylene (PB), poly (ethylene-co-1-butylene), poly ( butadiene), hydrogenated poly (butadiene), poly (ethylene oxide) -poly (propylene oxide) block copolymer or random copolymer and elastomer material having a backbone of poly (hydroxyalkanoate). For example, PDMS-4,4'-methylenebis (phenyl urea) (MPU) 0.4-isophorone bisurea units (IU) 0.6. As a main material for PDMS can be used as a polymer material having self-healing ability.

According to an embodiment of the present invention, the first electrical conductor may be a metal material, and may include, for example, any one or more of Ag, Au, Cu, Al, W, Mo, Ti, Cr, Ni, and Pt You can.

According to an embodiment of the present invention, the group conductive polymer composite may have a strain rate of 1700% or less.

According to an embodiment of the present invention, the first electrical conductor may have any one or more shapes of plate-like, spherical, polygonal, fibrous and irregular.

According to one embodiment of the invention, the first electrical conductor may have a size in the range of 500nm to 2㎛.

According to an embodiment of the present invention, the second electrical conductor may have a size of 50 nm or less.

According to an embodiment of the present invention made as described above, it is possible to provide a conductive polymer composite having superior elasticity and improving electrical conductivity as deformation occurs. In addition, even if damage occurs, self-healing is possible, and after self-healing, it is possible to provide a conductive polymer composite having excellent elasticity and electrical properties. Of course, the scope of the present invention is not limited by these effects.

1 is a result of observing the internal structure of the SHP-AgF complex prepared according to an embodiment of the present invention.
Figure 2 shows the change in electrical conductivity according to the AgF content of the SHP-AgF composite prepared according to an embodiment of the present invention.
Figure 3 shows the change in electrical conductivity according to the strain of the SHP-AgF composite prepared according to an embodiment of the present invention.
Figure 4 shows a stress-strain graph of the SHP-AgF composite prepared according to an embodiment of the present invention.
Figure 5 shows the change in electrical conductivity and self-boosting effect according to the strain of the SHP-AgF composite prepared according to an embodiment of the present invention.
6 to 8 show the results confirming the self-boosting effect of the SHP-AgF complex prepared according to an embodiment of the present invention.
9 is a conceptual diagram of the internal structure of the SHP-AgF composite prepared according to an embodiment of the present invention and shows the results of observation.
10 is a conceptual diagram showing a rearrangement mechanism according to a modification of the SHP-AgF complex prepared according to an embodiment of the present invention.
11 and 12 are the results of observing changes in the internal structure when modifying or maintaining the SHP-AgF complex prepared according to an embodiment of the present invention.
13 is a result of observing the properties of the conductive polymer composite prepared using PDMS and ECOFLEX according to an embodiment of the present invention.
14 is a result showing the self-healing ability of the SHP-AgF complex prepared according to an embodiment of the present invention.
15 and 16 show electrical and mechanical properties after self-healing of the SHP-AgF complex prepared according to an embodiment of the present invention.
17 is a view showing the structure of a type 2 SHP-AgF complex prepared according to an embodiment of the present invention.
Figure 18 shows the change in electrical conductivity according to the strain of the type 2 SHP-AgF composite prepared according to an embodiment of the present invention.
19 is a result of observing the process of recovery after modification of the type 2 SHP-AgF complex prepared according to an embodiment of the present invention.
Figure 20 shows the results of the repeated load test of the first and second type SHP-AgF composites prepared according to an embodiment of the present invention.
21 and 22 show changes in electrical conductivity according to stress-strain curves and strains of the first and second type SHP-AgF composites prepared according to an embodiment of the present invention.
23 is a result showing diode characteristics made of the first and second type SHP-AgF composites prepared according to an embodiment of the present invention.
24 is a view showing the structure of a type 3 SHP-AgF complex prepared according to an embodiment of the present invention.
25 is a flowchart illustrating a method of manufacturing a type 3 SHP-AgF complex prepared according to an embodiment of the present invention.
FIG. 26 is a step-by-step view of a result produced according to each step of the flowchart of FIG.
27 is a result of observing the internal structure of the type 3 SHP-AgF complex prepared according to an embodiment of the present invention.
28 is a result of observing the internal structure of the type 4 SHP-AgF complex prepared according to an embodiment of the present invention.
29 is a result showing variation in electrical conductivity of the first and third type SHP-AgF composites prepared according to an embodiment of the present invention.
30 is a result of repeated load tests of various types of SHP-AgF composites prepared according to an embodiment of the present invention.
Figure 31 shows the self-boosting effect of the type 4 SHP-AgF composite prepared according to an embodiment of the present invention.
Figure 32 shows the electrical properties of a system using an interconnect made of a type 4 SHP-AgF complex prepared according to an embodiment of the present invention.
33 is a manufacturing step and configuration of an interconnector configured to realize a self-healing artificial skin.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and the following embodiments make the disclosure of the present invention complete, and the scope of the invention to those skilled in the art It is provided to inform you completely. In addition, for convenience of description, in the drawings, the size of components may be exaggerated or reduced.

The conductive polymer composite according to an embodiment of the present invention has a structure in which a stretchable polymer is used as a matrix, and electrical conductor particles are dispersedly distributed therein. The stretchable polymer may be, for example, a self-healing polymer.

A polymer having self-healing ability refers to a polymer having the ability to heal damage itself and recover to its pre-damage state when damage to the internal structure occurs. These polymers are polydimethylsiloxane (PDMS), polyethyleneoxide (PEO), Perfluoropolyether (PFPE), polybutylene (PB), poly (ethylene-co-1-butylene), poly (butadiene), hydrogenated poly (butadiene), poly (ethylene oxide) -It includes an elastomer material having a poly (propylene oxide) block copolymer or a random copolymer and a poly (hydroxyalkanoate) as a backbone. A polymer material having self-healing ability may be prepared by adding a precursor material or a new unit to the elastomer having the above-described materials as a main chain. For example, PDMS-4,4'-methylenebis (phenyl urea) (MPU) 0.4-isophorone bisurea units (IU) 0.6. As a main material for PDMS can be used as a polymer material having self-healing ability.

 As another example, the stretchable polymer may include PDMS, ECOFLEX, silbione, and the like.

Electroconductive particles that are distributed and distributed therein are elements that allow the composite to have electrical conductivity. In addition, when the complex is deformed by an external force, dynamic rearrangement occurs inside, which is a factor that causes a change in the electrical conductivity of the complex.

The electroconductive particles may typically include metal particles. The metal may include metals having high electrical conductivity such as Ag, Au, and Cu. In addition, W, Mo, Ti, Cr, Ni and Pt may be included. These metal particles may be manufactured by a wet method, a powder metallurgy method, or the like, and may have various shapes according to a manufacturing method or a grinding method. For example, the metal particles may have a shape of a spherical shape, a flake shape, a plate shape, a fiber shape, a wire shape, and the like, and may have an irregular shape that cannot specify a shape. have.

In the conductive polymer composite according to the embodiment of the present invention, the electric conductors distributed and distributed are characterized by forming clusters in which particles of the same material of different sizes are disposed close to each other. For convenience, a particle having a large particle size is referred to as a first electric conductor particle, and a particle having a relatively small size is referred to as a second electric conductor particle. For example, the first electroconductor particles may have a size in the range of 500 nm to 2 μm, and the second electroconductor particles may have a size range of 50 nm or less (greater than 0).

The conductive polymer composite may be prepared by drying a mixed solution prepared by injecting electrical conductor particles into a solution in which a polymer constituting a matrix is dissolved, and the first electrical conductor particles are introduced to prepare such a mixed solution. It can be a raw material. In addition, the second electroconductor particles may be produced by using the input first electroconductor particles as a source. For example, when the first electroconductive particle is a metal particle, a metal having a nano-scale size by combining with electrons supplied from the matrix while metal ions are diffused into the matrix from the oxide layer formed on the surface of the metal particle in the matrix 2 Electroconductive particles can be formed. Therefore, the second metal particles are dispersed and distributed around the first metal particles as a source.

When an external force is applied to the conductive polymer composite according to the embodiment of the present invention having such a fine structure, plastic deformation occurs as the chain structure of the polymer constituting the matrix is rearranged. During the predetermined deformation of the matrix, the electrical conductor clusters distributed therein also rearrange, and the electrical conductivity characteristics of the electrical conductor clusters are remarkably changed.

For example, the composite according to the embodiment of the present invention may exhibit an increase in electrical conductivity during a process in which the length is stretched by an external force. As another example, when a predetermined time elapses in a state in which the deformation is maintained after the deformation of stretching the length of the composite by applying an external force, a significant increase in electrical conductivity may occur compared to the initial deformation. This will be described in more detail through experimental examples described later.

The conductive polymer composite according to the embodiment of the present invention may be implemented in various forms.

The type 1 conductive polymer composite is a type in which an electric conductor cluster is randomly distributed in a polymer matrix.

The second form is a form in which a capping region is formed by bonding a self-healing polymer containing no electrical conductor particles to at least a portion of the conductive polymer composite of the first shape.

The third form is a type that is divided into a high-density region with a relatively high density of electrically conductive clusters and a low-density region with a relatively low density in the polymer matrix.

The fourth form is a form in which a capping region is formed by bonding a self-healing polymer containing no electrical conductor particles to at least a portion of the conductive polymer composite of the third shape.

Hereinafter, experimental examples for helping understanding of the present invention will be described. This experimental example is provided to aid the understanding of the present invention, and of course, the present invention is not limited to the experimental example.

[Experimental Example]

 In this Experimental Example, PDMS-4,4'-methylenebis (phenyl urea) (MPU) 0.4-isophorone bisurea units (IU) 0.6 .., which are self-healing polymers of the matrix, were selected. Ag particles were selected.

1.5 g of PDMS-4,4'-methylenebis (phenyl urea) (MPU) 0.4-isophorone bisurea units (IU) 0.6) (hereinafter referred to as 'SHP') was mixed with 8 mL of chloroform to prepare a solution and stirred for 1 hour. Did. After adding flake-shaped Ag particles (hereinafter referred to as 'AgF') to the solution, the mixture was stirred for 30 minutes to disperse in the solution. The stirred mixed solution is poured onto a silicon dioxide (SiO ₂ ) wafer treated with octadecyltrimethoxysilane (OTMS) and cured at room temperature for 1 hour to form a conductive polymer composite in the form of a film (hereinafter referred to as “SHP-AgF composite”) It is produced). The film-shaped specimen could be easily separated from the OTMS-treated substrate after curing. The weight ratio of AgF: SHP was changed to 2: 1, 3: 1, 4: 1 and 5: 1, respectively, and it is referred to as Specimen 1, Specimen 2, Specimen 3 and Specimen 4, respectively. The size distribution (particle size distribution) of AgF ranged from 500 nm to 2 μm, which was confirmed by dynamic light scattering.

1 (a), (b), (c), and (d) show the results of observing the microstructures of Specimen 1, Specimen 2, Specimen 3 and Specimen 4, respectively, using a scanning electron microscope (SEM). Referring to FIG. 1, it can be seen that aggregates of AgF dispersed in the SHP matrix (agglomerates) are observed, and the higher the weight ratio of AgF, the more AgF aggregates are observed.

Figure 2 shows the results showing the change in electrical conductivity according to the volume ratio of AgF in the specimen to confirm the electrical properties of the prepared specimens. The result of fitting equation 1 to equation 2 according to the three-dimensional percolation theory is shown in FIG. 2. In Equations 1 and 2, ρ is the electrical conductivity of the specimen, ρ ⁰ is the electrical conductivity of the filler, V _f ⁰ and V _c ⁰ are the volume ratio of the filler and the initial threshold of percolation, respectively, and s is the critical index.

Referring to Figure 2, the initial conductivity of the specimen 1 and specimen 4 (i.e., the conductivity in the state without deformation after preparing the specimen) is 19.29Scm ^-1 and 833.33Scm ^-1 , the content of AgF contained in the specimen It could be confirmed that as this increase, it increased.

ρ = ρ ⁰ (Vf ⁰ -Vc ⁰ ) ^s (Equation 1)

log (ρ) = s [logρ ⁰ ] + log (Vf ⁰ -Vc ⁰ ) (Equation 2)

Figure 3 shows the results of measuring the change in electrical conductivity (conductivity) in real time while stretching the specimens 1 to 4 at room temperature to 100% strain rate per minute to 1200% strain (strain). Referring to FIG. 3, overall, the specimens showed an increase in electrical conductivity as the initial stretching progressed, but again a decrease in electrical conductivity over a certain strain. However, the electrical conductivity was significantly higher than before the deformation was applied, and the electrical conductivity was high even when severe strain exceeding 1000% was applied. For example, specimen 3 (AgF: SHP 4: 1) showed the highest electrical conductivity (741Scm ^-1 ) at 1200% strain. The higher the content of AgF contained in the specimen, the higher the increase rate of electrical conductivity according to the strain. In the case of Specimen 1 (AgF: SHP 2: 1), the AgF content was low, resulting in a low electrical conductivity, and no significant increase in strain. On the other hand, in the case of Specimen 4 (AgF: SHP 5: 1), the electrical conductivity rapidly increased according to the amount of deformation. However, due to the increased brittleness due to the high AgF content, an electrical short circuit occurred as the specimen fractured in the early stage of deformation. This can be confirmed from the stress-strain graph shown in FIG. 4.

5 shows the result of stretching the specimen 3 to 1700% strain. Referring to FIG. 5, in the case of specimen 3, it was not only stretched to 1700% strain, but was able to maintain a high electrical conductivity of 599 Scm ^-1 . For the specimen 3, the results of electrical conductivity according to the strain when annealing at 80 ° C and 130 ° C were additionally measured, and this is illustrated in FIG. 5. When the annealing was performed, the elasticity and conductivity of the specimen 3 was deteriorated, which is interpreted mostly because of oxidation of AgF or aggregation of the polymer matrix.

On the other hand, Fig. 5 shows the change in electrical conductivity when the specimen 3 is stretched to 1700% strain and then held for 1 hour while maintaining the strain, and for 20 hours. The electrical conductivity of the initial 599Scm ^-1 increased to about 1000Scm ^-1 when maintained for 1 hour, and rapidly increased to 4,479S cm ^-1 after the final 20 hours maintenance.

In order to observe these phenomena in more detail, a total of 4 steps were performed after stretching at 400% strain while real-time monitoring the electrical resistance of specimen 3 for 4 minutes, and the results are shown in FIGS. 6 and 7. .

6 and 7, the resistance values immediately after reaching deformation amounts of 400%, 800%, 1200%, and 1600% were 3.19 Ω, 9.49 Ω, 49.8 Ω, and 4.79 kΩ, respectively. After the corresponding amount of strain was maintained for 20 minutes, resistance values were measured, and the results were reduced to 2.62 Ω, 6.61 Ω, 23.91 Ω, and 102.68 Ω. In particular, when 11 hours were maintained after stretching at a strain of 1600%, the resistance value was 17.8 Ω, which was significantly lower than the state immediately after stretching. From this, it was confirmed that the electrical conductivity continuously increased as time elapsed while maintaining the deformation.

In addition, in order to observe the change in electrical conductivity before and after stretching, it is transformed to 800% and maintained for 2 hours, and compared with the electrical conductivity when stretched to 1000% and the electrical conductivity when stretched to 1000% without these steps. Fig. 8 shows the results. The path 1) shown in FIG. 8 is a step of relaxing the specimen 3 stretched at 1000% strain to 800% strain, the path 2) is a step of maintaining for 2 hours, and the path 3 is stretching again at 1000% strain. to be.

The electrical conductivity of the case without such an initial step of directly stretched to 1000% strain is yieoteuna 608.8Scm ^-1, when subjected to the above-described steps, it was confirmed to represent a higher value to 841.7Scm ^-1. This means that in the case of the composite according to the embodiment of the present invention, after the deformation is caused by external force, the electrical properties are changed by rearrangement of the internal structure while the deformation is maintained. The inventors who discovered this phenomenon called it the "self-boosting" phenomenon.

To investigate the cause of this self-boosting, the behavior of AgF dispersed in SHP was investigated.

9 is a conceptual diagram conceptually showing the structure of the SHP-AgF complex prepared according to the embodiment of the present invention and the results of actual observation thereof.

Referring to FIG. 9 (a), the SHP-AgF complex is a type 1 SHP-AgF complex, and has a microstructure in which AgF is randomly dispersed in the SHP matrix. Furthermore, the SHP-AgF complex further includes spontaneously formed nano-sized Ag nanoparticles (hereinafter referred to as “AgNP”) that are distributed and distributed around the AgF.

9 (b) to 9 (c) show the results of observing the internal structure of the SHP-AgF complex with a transmission electron microscope (TEM) and an energy spectroscopy device (EDS). Referring to (b) to (d) of FIG. 9, it can be confirmed that approximately spherical AgNPs having a diameter of about 20 nm or less are distributedly distributed around the AgF in the form of a plate.

The AgNP is interpreted to be spontaneously formed by the reaction of SHP, which is a matrix, during the manufacturing process. That is, AgNP may be formed by receiving electrons from the carbonyl group of SHP as Ag ⁺ ions generated from Ag ₂ O generated on the surface of AgF diffuse into the matrix.

AgNP spontaneously formed between AgFs may contribute to improving the conductive pathway. In this specification, a structure in which a number of AgNPs are distributed and distributed around AgF is referred to as an AgF-AgNP cluster.

FIG. 10 schematically shows a mechanism for self-alignment and rearrangement of AgF-AgNP clusters in a modified SHP matrix. 11 and 12 are the results of observing the microstructure of the SHP-AgF complex in steps shown in FIG. 10 by μ-CT and in-situ SEM.

Referring to the upper left and lower parts of FIG. 10, stretching is performed in a specific direction by tensile stress in a state in which AgF-AgNP clusters are dispersedly disposed in the SHP matrix.

Next, referring to the lower right portion of FIG. 10, as the elongation of the SHP-AgF complex increases, the AgF-AgNP clusters are aligned in the direction of tensile stress and the electrical conductivity of the SHP-AgF complex due to the efficient percolation path. Is improved. This is because the effective length of the percolation pathway becomes shorter after stretching of the SHP-AgF complex through self-alignment and rearrangement of AgF-AgNP clusters in the SHP matrix. The results of observing these steps are shown in FIGS. 11 and 12 (a).

Next, referring to the right middle portion of FIG. 10, the self-aligned path in the highly stretched state is partially broken and weakened due to small cracks in the SHP, thereby reducing electrical conductivity. This phenomenon is shown in Fig. 12 (b), SEM at 1000% strain showing self-alignment of AgF-AgNP clusters organized in cracked SHP and partial disconnection of self-aligned AgF-AgNP clusters. You can check it with an image. The high elasticity of the SHP-AgF complex maintains the percolation pathway even if there is a crack in the SHP due to the high toughness and elasticity of the SHP.

Next, referring to the upper right portion of FIG. 10, the AgF-AgNP cluster is rearranged over time while the strain is maintained, and the percolation path is naturally restored, and accordingly, the electrical conductivity is increased to a much higher value than the original state. Referring to (c) of FIG. 12, AgF particles that were disconnected at 1000% strain are rearranged while the strain is maintained, and it can be seen that the separated AgF-AgNPs are in contact with or close to each other to restore the conductive path.

This improvement in electrical conductivity can be explained by the dynamic rearrangement of AgF-AgNP clusters in the modified SHP matrix. Rearrangement of the AgF-AgNP cluster may be caused by the stress relaxation effect of the SHP-AgF complex, which is the main driving force.

 This stress relaxation effect can be explained by an increase in matrix free volume due to low crosslinking density due to excessive AgF, and low crosslinking density can be explained by spontaneous formation of AgNP.

In addition to this experimental example, the polymer to be the matrix was selected as Sylgard 184 and ECOFLEX, which are self-healing polymers without self-healing ability among PDMS, and it was confirmed whether or not a self-boosting effect due to stress relaxation was exhibited. Did.

13 (a) shows a graph of stress-strain of a composite using PDMS (Sylgard 184) and ECOFLEX as a matrix, and FIG. 13 (b) shows a change in electrical conductivity and a self-boosting effect according to the strain. have. As shown in FIG. 13, it was confirmed that the self-boosting effect was also exhibited when Sylgard 184 and ECOFLEX were used as the polymer matrix. From this, it can be interpreted that the stress relaxation effect in the polymer-AgF composite plays an important role in improving the electrical conductivity.

SHP-AgF complex using SHP as a matrix showed excellent self-healing effect by self-bonding. Fig. 14 (a) shows the cut form of the SHP-AgF complex of specimen 3, and Fig. 14 (b) shows that the part cut by self-healing is in a normal form when the cut part is rejoined at room temperature. The recovered results are shown. The interface region is removed by self-bonding, and it is composed of one body to confirm the process.

15 is a result of measuring the change in electrical conductivity according to deformation after self-healing the cut specimen 2. In the case of specimen 2, it can be confirmed that even after self-healing, the change in electrical conductivity due to stretching did not change significantly compared to before self-healing.

When heated in a self-bonding step, self-healing ability may be improved. The heating temperature may be performed, for example, in the range of 50 ° C to 100 ° C. FIG. 16 shows the stretching characteristics in the case of applying heat when self-healing after cutting for specimen 3, and when applying heat to 60 ° C during self-healing, at a level similar to that of the SHP-AgF complex (pristine) before cutting. It was confirmed that the stretching properties were exhibited. When the SHP-AgF complex (pristine) was 100% before self-cutting, it was 30% at room temperature, but 92% when heated to 60 ° C. It can be seen that the self-healing efficacy is improved as it is heated.

The structure of the SHP-AgF complex according to another embodiment of the present invention is shown in FIG. 17. Referring to FIG. 17, the SHP-AgF composite 200 according to the present embodiment stacks SHP-free AgF on top and bottom of the first type SHP-AgF composite 201 to form a capping region 202 , 203). This form is called type 2 SHP-AgF complex. The type 2 SHP-AgF composite may be prepared by laminating SHP-free AgF on the upper and lower surfaces of the type 1 SHP-AgF composite, and then bonding to each other by self-bonding, thereby forming a capping region. As described above, SHP spontaneously joins to form a continuum when the faces cut by self-healing are joined together. For the experiment, specimen 5 was prepared by bonding SHP to the upper and lower surfaces of the SHP-AgF composite of specimen 3.

18 shows a graph comparing the results of electrical conductivity according to the strain of specimen 5 and the fracture energy of specimen 3 and specimen 5.

Referring to Figure 18, the specimen 5 did not break up to a strain of 3500%, the electrical conductivity at this time was 1137Scm ^-1 . In addition, after maintaining for 60 hours, the electrical conductivity soared to 3086Scm ^-1 by self-boosting. These unprecedented electrical and mechanical properties are interpreted to be due to the effective energy relaxation effect at the interface between the SHP-AgF composite and the capping region SHP. This can be confirmed from the result that the fracture energy of the specimen 5 having the interface formed by the SHP and the SHP-AgF composite is significantly higher than that of the specimen 3, which is a type 1 SHP-AgF composite.

In addition, it was also confirmed that the self-boosting effect as in the type 1 SHP-AgF complex appeared in the type 2 SHP-AgF complex.

19 (a) and (b) show the results of observing the process of recovering over time after deforming the specimen 5 by 100% and 200%, respectively. Referring to FIG. 19, it can be seen that bending occurs at an initial stage after stretching the specimen 5, but rapidly recovers to the shape of the first specimen as the bent portion expands over time.

FIG. 20 is a result of observing the properties of the specimen 3 and the specimen 5 when the stretching (Strech) / relaxation (Realse) is repeated 10 periodically. “W / o encapsulation” in FIG. 20 means specimen 3, “w / encapsulation” means specimen 5, and so on in other drawings.

20 (a) shows the shape of the specimen used in the experiment, and (b) and (c) show the stress-strain results of the specimen 3 and the specimen 5. Referring to (b) and (c) of FIG. 20, it can be seen that the ability to recover after the specimen 5 is stretched to the specimen 3 is better. FIG. 20 (d) shows the stress-strain results when the primary specimens were first stretched for the same specimens and then stretched again after 10 minutes, and the aging effect of specimen 5 over time compared to specimen 3 ( aging effect).

21 shows the results of stress-strain after self-healing of specimens 3 and 5, and FIG. 22 shows the results of changes in electrical conductivity according to strain. Referring to both FIGS. 21 and 22, it can be seen that the specimen 5 exhibits better stretching characteristics than the specimen 3, and the change in electrical conductivity according to the stretching is small and thus more stable.

The self-boosting effect of the SHP-AgF composite according to the embodiment of the present invention may enable the existing electronic device to still work well even under extreme deformation conditions.

In order to prove this, after the diode was manufactured using the specimen 3 and the specimen 5, the current change according to the voltage was observed, and the results are shown in FIG. 23.

Referring to (b) of FIG. 23, in the case of specimen 3 (w / o Encapsulation), the voltage-current characteristic of a typical diode was initially shown, but after the deformation of 1700%, the voltage-current characteristic was largely due to an increase in resistance. Changed. However, due to the self-boosting effect, the retention time was increased to 15 minutes, 30 minutes, 45 minutes and 60 minutes, and the performance of the initial diode was restored by the dynamic rearrangement of AgF.

On the other hand, referring to (a) of FIG. 23, in the case of specimen 5 (w / Encapsulation), there was only a slight change in diode characteristics after 1700% deformation compared to the initial diode characteristic, and after maintaining a certain time after deformation The characteristics of the diode were initially restored by the self-boosting effect.

From this, the self-boosting effect when applying the type 1 SHP-AgF complex and the type 2 SHP-AgF complex to electronic devices could be demonstrated, and in the aspect of electrical stability, the type 2 SHP-AgF complex is the type 1 SHP- It was confirmed that it was relatively superior to the AgF complex.

The structure of the SHP-AgF complex according to another embodiment of the present invention is shown in FIG. 24. In the SHP-AgF complex 400, AgF is non-uniformly dispersed in the SHP matrix. Referring to FIG. 24, a high-density region 401 with a relatively high density of AgF and a low-density region 402 with a relatively small density of AgF are dispersed while moving from the high-density region toward the surface of any one surface of the composite. Includes. At this time, the density of AgF in the direction from the high-density region 401 to the low-density region 402 may be continuously reduced. Alternatively, the density may be intermittently reduced. Also, the high-density region 401 may be centered, and the low-density region 402 may be in a form surrounding the high-density region 401. Optionally, the low-density region on or near the surface may be a region consisting of almost pure SHP with a substantially low AgF density. Optionally, as shown in FIG. 24, the low-density regions 402 facing each other may be symmetrical with respect to the central axis C passing through the high-density region 401. This type of SHP-AgF complex is called type 3 SHP-AgF complex.

25 is a flowchart showing a method of manufacturing the type 3 SHP-AgF complex step by step, and FIG. 26 is a view showing a step-by-step manufacturing example.

Referring to FIG. 25, first, at least two SHP-AgF complexes having an AgF density 500 of one side higher than an AgF density 501 of the other side are prepared (step S100 and FIG. 26A). For convenience, this is called the partial SHP-AgF complex.

Partial SHP-AgF complexes having an asymmetric density of AgF may be prepared using a specific gravity difference between SHP and AgF. For example, during the process of pouring and drying the mixed solution of SHP solution and AgF onto the substrate, AgF having a higher specific gravity sinks down in the SHP solution, and thus AgF in the lower region in the dried SHP-AgF complex. The density will have a higher density than the upper region. Therefore, an asymmetric AgF-SHP composite having a high-density region 501 at the bottom and a low-density region 502 at the top can be manufactured. At this time, by controlling the drying conditions, the slower the drying time of the mixed solution, the higher the AgF density in the lower region can be adjusted. Using this method, a plurality of asymmetric SHP-AgF complexes can be prepared.

Next, after selecting at least two partial SHP-AgF complexes, high-density regions 501 having a high AgF density are disposed to be in contact with each other and then self-bonded (step S200 and FIG. 26B). At this time, in order to accelerate self-bonding, heat treatment may be performed during the bonding.

Optionally, capping regions 503 and 504 may be formed by additionally stacking SHP-free AgHP on the upper and lower surfaces of the type 3 SHP-AgF composite thus prepared (S3000 and FIG. 26C). Therefore, the capping regions 503 and 504 are disposed adjacent to the low-density region 502. The capping region can also be formed by self-bonding. Hereinafter, a form in which a capping region is formed on the surface of the type 3 SHP-AgF complex is referred to as a type 4 SHP-AgF complex.

27 (a) and 27 (b) show the cross-sections of Type 3 SHP-AgF composites (which are referred to as Specimen 6 and Specimen 7, respectively) when the weight ratio of AgF: SHP is 3: 1 and 4: 1, respectively, by SEM. It is the result of observation. The dotted line portion in FIG. 27 is a portion that was an interface region before bonding, and it can be seen that the interface region is removed by self-bonding to form one body.

FIG. 28 shows the results of observation of a cross-sectional photograph of a type 4 SHP-AgF composite (which is referred to as specimen 8) prepared by the above-described method by SEM. Between the first SHP-AgF composite (1st layer) at the top and the second SHP-AgF composite (2nd layer) at the bottom, there was a portion that was the interface region before bonding (in the middle dotted region in FIG. 28), the top and bottom SHP It can be confirmed that a capping region consisting of (Top encap. And Bottom encap.) Exists.

Type 3 SHP-AgF complexes or Type 4 SHP-AgF complexes can be unique candidates for making robust interconnects of deformable electronic circuits. This is because the portion where the high-density region having a high density of AgF is formed is located on a neutral machine surface that does not have an interface due to self-bonding and also relieves deformation due to bending. To prove this, the electrical conductivity of the specimen 3 and the specimen 7 was first stretched to 1500% strain, and this is illustrated in FIG. 29. As shown in FIG. 29, the specimen 7 (Double) exhibited much more stable electrical properties due to less variation in electrical conductivity due to deformation than the specimen 3 (Single).

Fig. 30 shows a 50% deformation of specimen 3 (single w / o encap.), Specimen 5 (single w / o encap.), Specimen 7 (double w / o encap.), And specimen 8 (double w / o encap.). Durability test results are shown that are repeated periodically. Referring to FIG. 30, the specimen 8 exhibited the best durability. On the other hand, the specimen 7 had no capping region, but showed better durability than the specimen 5 having the capping region.

Fig. 31 shows the self-boosting effect of Specimen 8. Referring to FIG. 31, the electrical conductivity of 155Scm ^-1 is shown at 1700% strain, and it can be seen that after 12 hours maintenance, it is increased to 588Scm ^-1 .

After the interconnector was prepared using a type 4 SHP-AgF complex such as specimen 8, it was applied to a flexible wireless EMG signal monitoring system. This bio-integrated system was uniformly mounted to the skin without the use of a conductive gel and covered with a transparent skin patch.

The fabricated interconnect exhibits low impedance (1.5 kΩ) at ~ 100 Hz, similar to the natural frequency of the flexor carpi ulnaris (FIG. 32A). Through the interconnection, real-time EMG monitoring of muscle contraction of the forearm flexor muscle can be performed very accurately and quickly without using a conductive gel (FIG. 32B). In addition to electrophysiological performance, the interconnect exhibited reliable mechanical properties within the 50% strain range before and after fatal damage. In addition, the initial and self-healing interconnects were stretched up to 4000% and 2980%, respectively.

33 shows the manufacturing steps and configuration of the interconnector configured to realize a self-healing artificial skin. The three conductors in which the SHP-AgF complex was combined with SHP were bonded as shown in FIG. 33 (a) to constitute a reference electrode, a ground electrode, and an active electrode. After configuring this as an interconnector that connects the human arm and the robot hand, a series of commands was transmitted through it, and it was confirmed that the commands were successfully delivered. In addition, after cutting the interconnector prepared as shown in FIG. 33 (b), it was self-healed while being heated at 60 ° C. for 1.5 hours, and then joined again. In this way, the self-healing interconnector was able to confirm that the robot hand accurately reproduces the human hand motion as before the self-healing because the command transmission was performed well.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

400: SHP-AgF complex
401: high density area
402; Low density area

Claims (16)

A conductive polymer composite region including electrical conductor particles; And
It is connected to at least a portion of the conductive polymer composite region, and includes a capping region that does not contain the electrical conductor particles,
The conductive polymer composite,
A matrix made of a polymer material having self-healing ability; And
It includes a plurality of electrical conductor clusters distributed in the matrix,
The electrical conductor cluster,
First electrical conductor particles; And
The same material as the first electrical conductor particles, the dispersion is distributed around the first electrical conductor particles, and includes a plurality of second electrical conductor particles having a smaller size than the first electrical conductor particles,
The conductive polymer composite,
When it is maintained for a predetermined time in a state deformed by an external force, the electrical conductivity increases, and a rearrangement step in which the spaced electrical conductor clusters are connected to each other as the deformation by the external force proceeds,
Conductive polymer composite with high elasticity. According to claim 1,
The capping region includes a polymer having self-healing ability,
Conductive polymer composite with high elasticity. According to claim 2,
The conductive polymer composite and the capping region are connected by self bonding,
Conductive polymer composite with high elasticity. delete delete According to claim 1,
The conductive polymer composite,
When it is maintained for a predetermined time in a state deformed by external force, the electrically conductive clusters spaced apart are connected to each other and rearranged.
Conductive polymer composite with high elasticity. According to claim 1,
The conductive polymer composite,
Relaxation of stress occurs as it is maintained for a predetermined time in a state deformed by external force,
Conductive polymer composite with high elasticity. According to claim 1,
The source of the second electrical conductor generation is the first electrical conductor,
Conductive polymer composite with high elasticity. According to claim 1,
Polymer materials with self-healing ability,
polydimethylsiloxane (PDMS), polyethyleneoxide (PEO), Perfluoropolyether (PFPE), polybutylene (PB), poly (ethylene-co-1-butylene), poly (butadiene), hydrogenated poly (butadiene), poly (ethylene oxide) -poly ( Propylene oxide) block copolymer or random copolymer, and an elastomer (elastomer material) containing one of poly (hydroxyalkanoate) as a backbone,
Conductive polymer composite with high elasticity. The method of claim 9,
Polymeric substances with self-healing capabilities include PDMS-4,4'-methylenebis (phenyl urea) (MPU) 0.4-isophorone bisurea units (IU) 0.6,
Conductive polymer composite with high elasticity. According to claim 1,
The first electrical conductor is a metal material,
Conductive polymer composite with high elasticity. The method of claim 11,
The metal material includes any one or more of Ag, Au, Cu, Al, W, Mo, Ti, Cr, Ni and Pt,
Conductive polymer composite with high elasticity. According to claim 1,
The conductive polymer composite,
Strain is less than 3500%,
Conductive polymer composite with high elasticity. According to claim 1,
The first electrical conductor has a shape of any one or more of plate-like, spherical, polygonal, fibrous and irregular,
Conductive polymer composite with high elasticity. According to claim 1,
The first electrical conductor has a size in the range of 500nm to 2㎛,
Conductive polymer composite with high elasticity. According to claim 1,
The second electrical conductor has a size of 50nm or less,
Conductive polymer composite with high elasticity.

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