Construction And Property Study Of Flexible Conductive Materials Based On Functionalized Ionic Liquids

In the era of Internet of things,flexible conductive materials have been unprecedented development.However,the inverse coupling between ion conductivity and mechanical strength limits the use of stretchable conductive materials.Therefore,new materials and methods must be explored to construct a rational conductive network in an elastic polymer matrix,leveraging the potential synergistic effects between the polymer matrix and the conductive network to balance conductivity and mechanical properties.In this paper,flexible conductive materials are constructed based on functionalized ionic liquids,which are mainly divided into the following two parts.The first part of this paper aims to prepare a new type of PIL-OH/IL-OH ionic gel containing high mechanical properties and ionic conductivity by in-situ photo-induced polymerization of hydroxylated ionic liquids monomer,which has similar structures to ionic liquids solvent.The mechanical and electrochemical properties depend on the crosslinking density and ionic liquid content.The PIL-OH/IL-OH ionic gel with 40 wt%[HOEMIm][TFSI]has a fracture elongation of 238.58%,a tensile strength of 2.73 MPa,and a high elastic modulus of 19.66 MPa,achieved by the formation of a PIL-OH/IL-OH cross-linked network structure.In addition,these sturdy PIL-OH/IL-OH ionic gels exhibit high ion conductivity at room temperature（up to 4.48 m S/cm）.High strength,high conductivity,and stretchable ionic gels lay the foundation for developing new electrolyte materials for energy storage devices,overcoming the conflict between mechanical strength and ion conductivity.The second part of this paper develops a high-performance"dry"ionic conductive elastomer（ICE）by copolymerizing carboxyl-functionalized monomer（IL-COOH）with methacrylic acid-2-methoxyethyl ester（MEA）,in line with the trend of ionic conductors’development.Based on a rational structural design,the ICE material exhibits excellent mechanical properties,with a fracture elongation of 1421%when n（IL-COOH）:n（MEA）=1:4.Combining the ethoxy chain-providing ionic crosslinker[DVIm-（EG）₃][TFSI]with the P（IL-co-MEA）backbone helps to improve conductivity and tensile strength but reduces stretchability.The glass transition temperature（T_g）of these prepared ternary ionic conductive elastomers was lower than room temperature.The thermal stability of these conductive elastomers was above 300 ^oC,achieving ion conduction at room temperature without the addition of conductive fillers（up to 0.046m S/cm）.Compared with traditional polyacrylamide（PAM）hydrogels,it does not exhibit weight loss after 100 hours at room temperature.This work provides experimental and theoretical support for the development of new flexible sensors,showing potential applications in human-machine interaction.Finally,a brief discussion is given on the direction of further work.