Humidity sensors based on Li-loaded nanoporous polymers

Nanoporous polymer based on divinylbenzene was synthesized by radical polymerization with a solvothermal route. The nanoporous characteristic of the resultant polymer poly(divinylbenzene) (PDVB) was determined by a series of characterizations. The hydrophobic porous polymer was used as the host to prepare composited humidity sensitive materials. Different levels of LiCl were loaded into the nanoporous polymer and their humidity sensing properties were researched. Humidity sensitivities of the composites were greatly improved by LiCl loading compared with pure PDVB. The sensor based on 5 wt% LiCl/PDVB showed the best sensing properties to relative humidity (RH). The impedance of the optimum sensor changed three orders of magnitude over the whole humidity range, with a good linearity and rapid response. The mechanism by the complex impedance plots suggests the protons are the domination carrier in low humidities and ions (Li+ and Cl−) in a high humidity range. The results demonstrate nanoporous polymers are a new kind of promising materials for humidity sensors.