Polyaniline Nanostructures with Controlled Morphology Via Pseudo-high Dilution Technique

Abstract

The influence of dopant acid (hydrochloric acid; sulfuric acid; 2-acrylamido-2-methyl-1-propanesulfonic acid; chloroacetic acid; p-toluenesulfonic acid mono hydrate and salicylic acid) on the molecular structure, morphology, crystallinity, thermal stability and conductivity of polyaniline nanostructures, synthesized by using pseudo-high dilution, was studied The oxidation polymerization of a highly concentrated aniline solution, namely, 0.4M, provided a high polymer yield, utilizing ammonium persulfate as the oxidant. This pathway always produced polyaniline nanostructures of tunable morphology, moderate crystallinity and semiconducting properties. The infrared spectroscopy provided evidence that the polymerization occurred via the head-to-tail mechanism. Utilizing hydrochloric acid as a dopant led to the most thermally stable polymer. The conductivity results proved that sulfuric acid was the best dopant among the various used ones. 0.6:1 sulfuric acid/aniline molar ratio resulted in polyaniline nanostructures with a direct conductivity of 2.05 S/cm.