Polystyrene/polyaniline nanoblends for sensing of aliphatic alcohols

Electrically conductive polymer blends containing polyaniline doped with dodecyl benzene sulfonic acid (PANI-DBSA) dispersed in a polystyrene (PS) matrix were studied as sensing materials for an homologous series of alcohols, including, methanol, ethanol and 1-propanol. The blends were prepared by melt processing of PS/PANI-DBSA powders (prepared by blending of dispersions of PANI-DBSA and PS followed by coagulation) characterized by high conductivities at relatively low PANI-DBSA concentrations. Extruded PS/PANI-DBSA filaments produced by a capillary rheometer process at various shear rate levels were used in the sensing experiments. A significant conductivity increase was observed upon exposure of the filaments to the various alcohols. Some systems have demonstrated high sensitivity (relative resistance changes of few orders of magnitude) towards the studied alcohols combined with outstanding reproducibility and recovery behavior. The sensing performance and mechanism of these filaments are governed by the dopant content and method of processing. Under certain processing conditions a unique PANI network containing nanosized particles is realized, resulting in very high sensitivity levels. It is suggested that the observed resistance changes of these PS/PANI filaments result from enhanced charge carrier mobility through hopping processes between adjacent PANI particles.