Humidity sensing studies on conducting polymers: Polyaniline and polypyrrole

Abstract

• Polyaniline (PANI) and Polypyrrole (PPy) - synthesized by in-situ polymerization and chemical polymerization method respectively. • The film of the samples prepared by spin deposition technique. • Humidity sensing response for PANI and PPy was experimentally established in the RH range of 10–97 %. • The mechanism for sensing: Grotthus mechanism was discussed thoroughly. The present paper addresses, a comparative canvas on the humidity sensing performance of the conducting polymers: Polyaniline (PANI) and Polypyrrole (PPy). For the purpose, PANI and PPy were synthesized by in-situ polymerization and chemical oxidative polymerization method respectively. The polymer matrix was functionally characterized by FTIR and XRD studies, and phonological characterized by SEM techniques. For the humidity monitoring measurements, the film of the PANI and PPy were made by fixing each sample on the simple substrate using an efficient spin deposition technique. The PANI has depicted a sensing response (S R ) of 41 % in the RH range of 10–97 % with timing behavior of 180 s of 60 s respectively. But PPy depicted a S R of 71 % over the RH 10–97 % with a response and recovery time of 63 s and 60 s respectively. The PPy has shown a better real sensitivity of 0.006 Ώ/% RH, lower limit of detection (LOD) of 11 % RH, best linearity of 0.9818, less humidity-hysteresis of 15 % and maximum stability over a period of two months. Along with these, physical features are also increased in PPy compared to PANI. The sensing operation has thoroughly discussed on the shaping of three layers in accordance with Grotthus mechanism, later followed by condensation.