Preparation Of Organic-inorganic Composite Polyimide Aerogel And Study Of Its Electromechanical Response Propertie

Due to the rapid development of intelligent electronic equipment in aerospace,transportation and other high-tech fields,the demand for sensitive pressure sensors is increasing.However,the application of most resistance pressure sensors in high temperature environments will lead to poor mechanical properties,sensor failure and other problems.At the same time,it is difficult for existing sensors to have high sensitivity,wide response range,excellent cyclic stability,good linear relationship and self-monitoring capabilities,which poses a challenge to the performance of flexible sensing materials used in related equipment.In this paper,anisotropic polyimide aerogels were used as the matrix,and nanosilver and carbon nanotubes were used as fillers to prepare the sensor.Composite aerogels（PI/Ag NPs）with silver nanoparticles coated polyimide layer with scorpion pectine-like microstructures were prepared by freeze-drying the precursor solution followed by thermal imination reaction and impregnation with silver nanoparticles solution.The microstructure provides sufficient structural strength for support while providing contact and recovery points for the conductive network.The surface silver layer thickness of PI/Ag NPs-1 is 78-120 nm.The composite aerogel has an electrical response under wide tension（PI/Ag NPs-2 aerogel changes from-15.63 k Pa at 30%tensile stress to 69.25 k Pa at 70%compressive stress）.The composite aerogel has excellent sensing properties,including good resistance change（89%）,ultra-high sensitivity(6.9 k Pa^-1),the ability to detect different deformations（compression,tension,and bending）,and low fatigue after3,000 load-to-unload cycles.In addition,these aerogels can withstand temperatures up to250℃and show good conductivity consistency at both high and room temperature.These PI/Ag NPs aerogels can be used as sensors in extreme conditions,such as aero-engine peripheral electronics.Secondly,by using the method of step by step a frozen,the preparation of polyimide/carbon nanotubes（PI/MWCNT）aerogel,within the aerogel to build six electric circuit structure,local compression experiments were carried out to study one-dimensional plane and two-dimensional domains responsiveness.By verifying the coupling relationship between loading position,stress and resistance changes,the large area sensing response performance of aerogel is improved,and the self-monitoring application of polyimide conducting aerogel is expanded.In this paper,based on the current problems,which restrict the development of the sensor by controlling the material physical properties,optimization of structure design and so on,greatly improve the comprehensive performance of the sensor,make it meet the demand of increasingly complex applications.