Preparation And Application Of Flexible Stretchable Ionic Conductors

Flexible electronic products have been widely used in various applications,such as flexible transistors,smart sensors,flexible energy harvesting and storage,flexible displays and artificial skin.The main advantages of flexible electronic products compared to rigid flat panel displays are high flexibility,low-cost manufacturing?such as inkjet printing and roll-to-roll processing?,and inexpensive substrate materials?such as plastic?.However,flexible electronic devices face challenges in applications where the device is subjected to large deformations?eg,bending,twisting,and stretching?or tightly coupled with curved surfaces?eg,human skin?,which has led to the emergence of stretchable electronic devices.Stretchable electronic technology is a technology for constructing electronic circuits on a stretchable substrate or by embedding electronic circuits in a stretchable matrix.In the past decade,the field of stretchable electronics has made exciting progress.The application of stretchable electronic devices in biocompatibility,wearable and compliant devices has aroused great interest.In these applications,flexible stretchable conductors with inherent adhesion,toughness and mechanical flexibility play a vital role in achieving flexible stretchability of the device.Existing stretchable conductors are mainly conductive composite materials:rigid conductors such as metals,carbon materials and conductive polymers are combined with stretchable elastomers to obtain conductivity and stretchability.This method usually achieves high conductivity(?10² S cm^-1).However,for the above-mentioned stretchable conductors,the compatibility between the conductive component and the elastic network is still a problem that is often ignored and difficult to solve,and always results in poor mechanical and electrical properties.The main reason is that the conductive network will be interrupted during the deformation process and cause irreversible damage to the electrical properties after stretching.At the same time,due to the weak interaction between the conductive network and the stretchable network,this leads to a decrease in mechanical properties.In response to the above problems,by introducing an ionic electrolyte salt having better affinity with the polymer network into the polymer network,a stretchable ionic conductor with excellent stretchability and conductivity is obtained.Moreover,due to the good compatibility of the conductive component and the electrolyte network,the prepared stretchable conductor can ensure the continuity of the conductive phase during the deformation process to ensure the conductive performance during the stretching process.The main research results are as follows:?1?In this study,amphiphilic small molecule DGI was successfully synthesized through a two-step esterification reaction.First,through the improvement of the synthesis method reported by Kouichi Naitoh,etc.,and then understanding the reaction principle,and then combining the existing equipment of the research group and some existing synthesis experience,the reaction device,synthesis method and later purification method were optimized and improved.And finally successfully prepared amphiphilic small molecule DGI.Then,we conducted a purity test on the obtained DGI samples.A number of test results showed that we successfully obtained DGI and at the same time had a very high purity.?2?In this study,iridescent hydrogel?PDGI/PAAm?was successfully prepared by introducing layered PDGI into PAAm hydrogel.Due to the Bragg diffraction of visible light in the periodic layered structure,the gel showed a bright structural color,and the color can be changed quickly by compressing or stretching.At the same time,the introduction of PDGI has also greatly improved the mechanical properties of hydrogels.Then,by soaking the resulting iridescent hydrogel in a lithium chloride salt solution,we successfully obtained a stretchable iridescent hydrogel ionic conductor.Finally,based on the iridescent hydrogel ion conductor,a capacitive sensor device was successfully prepared,and the device was used to monitor different actions.The device showed good response to different actions and different forces.?3?This study used a simple one-step photo-polymerization method to prepare ICE.The prepared ICE has many advantages,including transparency,high stretchability,electrical conductivity,and can heal itself under ambient conditions without the need for any external conditions.Moreover,the prepared ICE shows excellent stability,such as air stability,high temperature stability,adhesion stability,and electrochemical stability.In addition,through the copolymerization strategy,the electrical conductivity of ICE was improved.Finally,a copolymerized ICE was used to prepare a touch sensor and achieved specific responses to four stimuli,which means that the sensor has a high selectivity for different stimuli.