Construction And Mechanism Of Novel Highly Stretchable Ionogel

Ionogel,as a new type of gel polymer electrolyte material,has more and more applications in flexible energy storage devices,wearable electronic devices,flexible sensors and other devices.In order to meet the requirements of stretch and distortion of functional and smart devices,the preparation of novel ionogel polymer electrolyte with excellent flexibility,high stretchability and high conductivity has attracted much attention as a hot research area throughout the world.In this paper,a high-stretchable and self-healable polyvinyl alcohol(PVA)-based physical ionogel containing a liquid crystal texture was first prepared by a physical mixing method.And then,a high-stretchable chemical ionogels with chemical and physical cross-linking points based on gelatin and poly(diacetone acrylamide)(PDAAM)were prepared by chemical crosslinking method.We have conducted a detailed study on the mechanical properties,tensile properties,conductive properties and self-healing properties of the highly stretchable ionogels.The results are as follows:(1)A highly stretchable and self-healing ionogel was prepared using PVA as a matrix material in a 1-allyl-3-methylimidazolium chloride ionic liquid by physical cross-linking.It can be observed under a polarizing microscope that as the PVA content and degree of stretching increase,the liquid crystal phenomenon increases.The rheological measurements revealed that the storage modulus of the ionogel gradually increases to 50 KPa,and the gel-sol transition temperature increases from 79 ~oC to 121 ~oC,with the PVA content increases.The mechanical property test results show that the ionogel has excellent tensile properties,with the elongation at break can be as high as 700%.Electrochemical performance tests show that the ionic conductivity is above 1.0×10~-55 S/cm,which increases with the increase of the ionic liquid content,and the prepared sensor has excellent cycle stability.(2)A new chemical cross-linked ionogel with excellent self-healability and stretchability based gelatin was synthesized via the Schiff based reaction in ionic liquid of 1-ethyl-3-methylimidazolium acetate(EMIMAc).Rheological measurements revealed that the plateaus modulus in storage modulus increases with the content of gelatin increases.The ionogels displayed good thermal mechanical stability as the chemical networks were not destroyed even at temperature up to 140 ~oC.The prepared ionogel has high tensile properties and its elongation at break can reach 400%.Importantly,the room temperature ionic conductivity of ionogel was higher than 1.0×10~-33 S/cm,and the supercapacitors with this ionogel electrolyte showed temperature-dependent specific capacitance and remarkable flexible performance.(3)Using poly(diacetone acrylamide)(PDAAM)as the base material and acrylate-terminated hyperbranched polyester(HP-A)as the cross-linking agent,a novel highly stretchable ionogel electrolyte material was prepared in ionic liquid of 1-butyl-3-methylimidazole bis[(trifluoromethyl)sulfonyl]imide with both physical cross-linking caused by intermolecular hydrogen bonding interactions and chemical cross-linking from hyperbranched polymer cross-linker.The rheological results revealed that the plateaus modulus in storage modulus increases with increase of matrix content and cross-linker content and up to about 10~4 Pa.Although the elongation at break decreases with the increase of cross-linker content,the strength gradually increases,and the elongation at break of the prepared ionogel can reach about 1200%.The room temperature conductivity of ionogel is above 1.0×10~-33 S/cm,which has potential application value.