US-12617899-B2 - Electrically conductive elastomer and method of synthesizing the same

Abstract

Provided is an electrically conductive elastomer with high stretchability and high durability. A method of synthesizing an electrically conductive elastomer includes (a) preparing a eutectic solvent by mixing quaternary ammonium salt and organic acid, and (b) adding and blending the eutectic solvent with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a photocuring agent, and a crosslinker and performing photopolymerization.

Inventors

• Sang Woo Kim
• Jun Ho LIM

Assignees

• KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY

Dates

Publication Date

20260505

Application Date

20221101

Priority Date

20211221

Claims (10)

1. 1 . A method of synthesizing an electrically conductive elastomer, the method comprising: (a) preparing a eutectic solvent by mixing and causing reaction between quaternary ammonium salt and organic acid; and (b) adding and blending the eutectic solvent with poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a photocuring agent, and a crosslinker and then performing photopolymerization, wherein the polymerization of (b) prepares a polymer in which PEDOT:PSS nanoparticles have a coil-shaped benzoid structure; and transforming the coil-shaped benzoid structure of at least a portion of the PEDOT:PSS nanoparticles into a linear quinoid structure, wherein the photocuring agent and the crosslinker are blended in a molar ratio of 0.1 to 0.3 of the organic acid in step (b).
2. 2 . The method of claim 1 , further comprising performing sulfuric acid treatment on the elastomer synthesized in step (b) to transform the coil-shaped benzoid structure of at least a portion of the PEDOT:PSS nanoparticles into the linear quinoid structure.
3. 3 . The method of claim 1 , wherein the quaternary ammonium salt and the organic acid are mixed in a molar ratio of 1:1 to 1:3.
4. 4 . The method of claim 1 , further comprising adding 0.5 mol % to 2 mol % of phytic acid with respect to the organic acid.
5. 5 . The method of claim 1 , wherein the quaternary ammonium salt comprises choline chloride, tetramethylammonium, acetylcholine, benzalkonium chloride, or cetrimonium chloride.
6. 6 . The method of claim 1 , wherein the organic acid comprises any one selected from the group consisting of urea, thiourea, 1-methyl urea, 1,3-dimethyl urea, 1,1-dimethyl urea, acetamide, benzamide, ethylene glycol, glycerol, adipic acid, acrylic acid, benzoic acid, citric acid, malonic acid, oxalic acid, phenylacetic acid, phenylpropionic acid, succinic acid, lactic acid, and tricarboxylic acid.
7. 7 . The method of claim 1 , wherein a content of PEDOT:PSS ranges from 0.5 wt % to 10 wt % with respect to a total mass of PEDOT:PSS and the eutectic solvent in step (b).
8. 8 . An electrically conductive elastomer prepared by the method of claim 1 in which poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) nanoparticles are dispersed in an ionic conductor matrix formed from a eutectic solvent prepared by causing reaction between quaternary ammonium salt and organic acid, wherein PEDOT:PSS comprises a linear quinoid structure from which some of PSS is removed.
9. 9 . The electrically conductive elastomer of claim 8 , wherein the ionic conductor is formed from a eutectic solvent prepared by mixing choline chloride and acrylic acid.
10. 10 . A biosensor comprising the electrically conductive elastomer of claim 8 .

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION This application claims the benefit of Korean Patent Application No. 10-2021-0183912, filed on Dec. 21, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrically conductive elastomer and, more particularly, to a high-durability conductive elastomer synthesized by adding a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conductive polymer to an ionic eutectic solvent, and a biosensor manufactured using the conductive elastomer. 2. Description of the Related Art Currently, a technology for manufacturing light-weighted, flexible, and wearable devices by using a stretchable material that does not cause degradation of electromechanical performance of a system under deformation similar to that of human skin is being highly developed. In addition, research is being actively conducted on flexible body-attachable electronic skin technology that mimics various functions of human skin. To manufacture such devices with flexibility, materials having high mechanical stretchability and high conductivity are required. As the above-described materials, hydrogels and conductive elastomers stand out. The hydrogel-based materials have a self-healing function and a high transmittance. However, the function is lost when water evaporates in a dry environment. In contrast, the conductive elastomers are being commonly used in various industrial fields due to their high electrical conductivity, processability, flexibility, and easy synthesizability. With the current increase in demand for wearable devices such as stretchable organic light-emitting diodes (OLEDs), flexible organic photovoltaics, and patch-type electronic skins, high-stretchability and high-durability electrically conductive materials capable of transmitting signals and having flexibility so as not to be damaged by body motions are being increasingly demanded. SUMMARY OF THE INVENTION The present invention provides an electrically conductive elastomer with high stretchability and high durability. However, the scope of the present invention is not limited thereto. According to an aspect of the present invention, there is provided a method of synthesizing an electrically conductive elastomer, the method including (a) preparing a eutectic solvent by mixing and causing reaction between quaternary ammonium salt and organic acid, and (b) adding and blending the eutectic solvent with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a photocuring agent, and a crosslinker and then performing photopolymerization. The method may further include performing sulfuric acid treatment on the elastomer synthesized in step (b). The quaternary ammonium salt and the organic acid may be mixed in a molar ratio of 1:1 to 1:3. The method may further include adding 0.5 mol % to 2 mol % of phytic acid with respect to the organic acid. The quaternary ammonium salt may include choline chloride, tetramethylammonium, acetylcholine, benzalkonium chloride, or cetrimonium chloride. The organic acid may include any one selected from the group consisting of urea, thiourea, 1-methyl urea, 1,3-dimethyl urea, 1,1-dimethyl urea, acetamide, benzamide, ethylene glycol, glycerol, adipic acid, acrylic acid, benzoic acid, citric acid, malonic acid, oxalic acid, phenylacetic acid, phenylpropionic acid, succinic acid, lactic acid, and tricarboxylic acid. A content of PEDOT:PSS may range from 0.5 wt % to 10 wt % with respect to a total mass of PEDOT:PSS and the eutectic solvent in step (b). The photocuring agent and the crosslinker may be blended in a molar ratio of 0.1 to 0.3 of the organic acid in step (b). According to another aspect of the present invention, there is provided an electrically conductive elastomer in which poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) nanoparticles are dispersed in an ionic conductor matrix formed from a eutectic solvent prepared by causing reaction between quaternary ammonium salt and organic acid, wherein PEDOT:PSS includes a linear quinoid structure from which some of PSS is removed. The ionic conductor may be formed from a eutectic solvent prepared by mixing choline chloride and acrylic acid. According to another aspect of the present invention, there is provided a biosensor including the above-described electrically conductive elastomer. BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent by describing in detail embodiments thereof with reference to the attached drawings in which: FIG. 1A and FIG. 1B are conceptual views showing reactions for synthesizing an electrically conductive elastomer according to an embodiment of the present invention; FIG. 2A, FIG. 2B, and FIG. 2C are scanning electron microscope (SEM) images of embodi