Preparation Of Conductive Polyimide Composite Aerogel And Research On Its Pressure Sensing Characteristics

With the foreseeable prosperity of artificial intelligence,the demand for wearable pressure sensors is increasing.Recently,conductive polymer composites（CPCs）based pressure sensor has attracted much attention due to its unique advantages of good flexibility,low cost and easy for large-scale production.However,the imbalance between high sensitivity and wide response range,poor fatigue resistance,unstable thermodynamic properties and other problems need to be solved urgently.In this study,high strength and good temperature tolerance polyimide（PI）was applied as polymer matrix,lightweight and porous conductive composite aerogel-based pressure sensor was prepared through the optimization design of structure.The specific research contents are as follows:1.A lightweight and porous PI/carbon nanotube（CNT）composite aerogel was successfully prepared via freeze-drying and thermal imidization process using water-soluble PI prepolymer-poly（amic acid）（PAA）as matrix and carbon nanotubes as conductive filler.Due to the strong interfacial bonding force between PI and CNT,the prepared PI/CNT composite aerogels exhibit excellent structural stability and can withstand compression up to 80%,bending at 180°or even twisting at 360°.The composite aerogel exhibits brilliant sensing performance,including wide sensing range（80%strain,61 k Pa）,ultralow detection limit（0.1%strain,<10 Pa）,fast response time（50 ms）and recovery time（70 ms）,remarkable long-term stability（1000 cycles）and so on.In addition,the composite aerogel still possesses stable sensing properties after annealing under different high temperatures,which proves its excellent high temperature resistance and structural stability.Finally,PI/CNT composite aerogel-based pressure sensors can effectively monitor a variety of human movements（including airflow,pulse,vocal cord vibration and human movement）and precisely detect pressure distribution when it is assembled into E-skin,demonstrating its great potential to serve as high-performance wearable pressure sensor.2.Conductive polyimide nanofiber（PINF）/MXene composite aerogel with typical“layer-strut”bracing hierarchical nanofibrous cellular structure has been developed via the simple freeze-drying using polyimide nanofibers（PINF）,PAA,and new two-dimensional filler MXene as matrix,adhesive conductive and filler,respectively.Benefiting from the porous architecture and robust bonding between PINF and MXene,the prepared PINF/MXene composite aerogel exhibits an ultralow density,intriguing temperature tolerance,superior compressibility and recoverability（up to 90%strain）.The composite aerogel can be used as a piezoresistive sensor,performing outstanding sensing capacity（90%strain,85.21 k Pa）,an ultralow detection limit（0.5%strain,0.01k Pa）,robust fatigue resistance over 1000 cycles,excellent piezoresistance sensing stability.Besides,the composite aerogel-based pressure sensor still has stable response in the temperature range of-196℃-150℃,showing the application potential in the extreme high/low temperature environment.Finally,the composite aerogel also exhibits superior oil/water separation properties such as high adsorption capacity(55.85 to 135.29 g·g^-1)and stable recyclability due to its hydrophobicity and robust hierarchical porous structure,showing great application potential as oil-water separation materials.