Synthesis and electrochemical characteristics of polyaniline based composite electrodes

Abstract

The present work is concerned with the modification of polyaniline to enhance the redox switching and reversibility at the electrode/electrolyte interface when the polyaniline is applied as an electrode material. In chapter III, the structure and doping behaviors of the poly(p-styrene sulfonic acid) (PSSA)-doped polyaniline and the poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS)-doped polyaniline were investigated by conductivity measurement, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The conductivities of the PSSA-doped polyaniline composites are higher than those of the PAMPS-doped polyaniline composites of the same composition, given by acid to aniline ratio, up to about 2 orders of magnitude. The conductivity difference between the two different polymeric acid-doped polyaniline composites could be explained by the difference in the degree of the steric hindrance between the two acid moieties arising from their bulkiness difference. The PSSA and the PAMPS-doped polyaniline systems revealed the same optimum composition of 1/1 for maximum conductivity. The maximum conductivity seems to be attributed to the increase in the doping level and the decrease in the order and packing density of the polyaniline subchain alignment with the increase of the acid to aniline ratio. In chapter IV, the conductivities of the polyaniline composites doped with the copolymeric acids such as poly(methyl methacrylate-co-p-styrene sulfonic acid) (PMMA-co-SSA), poly(styrene-co-p-styrene sulfonic acid) (PS-co-SSA), and poly(methyl methacrylate-co-2-acrylamido-2-methyl-1-propane sulfonic acid) (PMMA-co-AMPS) were investigated as a function of the acid content in the copolymeric acids. With the fixed ratio of acid to aniline (1/1) in the polyaniline composites, the conductivities of the copolymeric acid-doped polyanilines decreased as the acid content in the copolymeric acids decreased. This could be attributed to the non-a...