Vapor phase sensing response of doped polyaniline-poly (vinyl alcohol) composite membrane to different aliphatic alcohols

Abstract

Conductive polymers in the form of pellet and coating on a suitable substrate have been extensively used in recent years as sensor materials for the vapor phase sensing of aliphatic alcohols. But due to lack of mechanical stability and reversible adsorption/desorption of alcohol molecules the use of conducting polymers in the above forms suffers from limited repeatability of sensing response. Here, we have developed some mechanically stable free standing doped polyaniline-poly (vinyl alcohol) (PVA-PANI) composite membranes as efficient materials for sensing of aliphatic alcohols in vapor phase. Camphor sulphonic acid (CSA), L-aspartic acid (ASP) and p-toluene sulphonic acid (PTSA) were used as dopants at the time of synthesis of polyaniline in presence of sodium dodecyl sulfate (SDS) by oxidative polymerization of aniline using 1 (M) ferric chloride solution at 0°C under nitrogen atmosphere. Membranes of thickness 0.15–0.18mm were prepared with PVA in dimethyl sulphoxide (DMSO) by solution casting. Doped polymer membranes were spectroscopically characterized. It has been observed that dopant has significant effect on the formation of polyaniline morphology in presence of SDS as seen in SEM images. Conductivities of doped membranes, viz., CSA-PANI-PVA, PTSA-PANI-PVA and ASP-PANI-PVA, are 9.30×10−3, 3.86×10−4 and 4.83×10−4S/cm respectively. Membranes have shown good sensing responses and repeatability of response patterns towards aliphatic alcohols with lower response time.