Preparation of lithium-modified porous polymer for enhanced humidity sensitive properties

A porous polymer was synthesized through self-polymerization of monomer 3-hydroxybenzoic acid by the Friedel-Crafts alkylation reaction. To enhance hydrophilic properties of the resultant polymer (P3HBA), it was treated with lithium hydroxide to obtain lithium-modified polymer (Li@P3HBA). The structures of P3HBA and Li@P3HBA were characterized and their humidity sensitive properties were researched. Compared with P3HBA sensor, Li@P3HBA sensor exhibited improved humidity sensing properties. Li@P3HBA sensor showed the impedance change of three orders of magnitude at the whole humidity range, with a good linearity, litter hysteresis, rapid response and good long-term stability. Our results demonstrated that lithium-modified polymer with stable porous hydrophilic framework had the potential to fabricate humidity sensor for practical application.