Humidity sensing properties of LiCl-loaded porous polymers with good stability and rapid response and recovery

A novel porous polymer was synthesized by Friedel-Crafts alkylation polymerization, and the structure and characteristic of the polymer was determined by Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained polymer was used to prepare humidity sensitive composites by loading LiCl. Compared with the pure polymer, LiCl-loaded composites showed improved humidity sensing properties and the 4 wt% LiCl/polymer sensor showed the best sensing properties. The impedance of the optimum sensor changed near four orders of magnitude over the whole humidity range, with a good linearity, little hysteresis, good stability and short response and recovery times (2 and 7 s, respectively). The complex impedance plots were used to research conductive mechanism.