A guest/host composite of Fe(NO3)3/nanoporous polytriphenylamine assembly for humidity sensor

A nanoporous organic polymer based on triphenylamine was synthesized, and the structure and morphology of the resultant polytriphenylamine (PTPA) were described by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption/desorption analysis. PTPA was acted as the host to load the guest Fe(NO3)3 for preparing humidity sensitive composites. Compared with pure PTPA sensor, Fe(NO3)3/PTPA sensors showed improved humidity sensitive properties, especially the 20 wt% Fe(NO3)3/PTPA sensor. The impedance of the 20 wt% Fe(NO3)3/PTPA sensor changed four orders of magnitude over the whole humidity range, with a good linearity, litter hysteresis, rapid response and good long-time stability. The complex impedance plots and direct current (DC) reverse polarity method were used to research the mechanism of the optimized sensor.