Water-Soluble Polyaniline fromγ-Ray-InducedN-Acylation Graft Copolymerization with Acrylic Acid in the Emeraldine State

The effect of γ-ray irradation on the emeraldine (EM) base form of polyaniline was investigated. The process of γ-ray, UV, and thermally-induced graft copolymerization of EM base with acrylic acid (AAc) in a number of solvents and co-solvents were compared in an attempt to prepare a water-solube EM through N-acylation. The presence of N-acylation was investigated by thermogravimetric (TG) analysis, Fourrier transform infrared (FTIR) spectroscopy., and X-ray photoelectron spectroscopy (XPS). In all cases, the grapht concentration and the resulting surface conductivity were shown to be a function of the monomer concentration. The thermostability and weight loss behavior of the grapht-copolymerized EM included those that were characteristic of the EM base, the AAc polymer and the amide polymer. Some of the grapht-modified EM base samples exhibited good water solubility. In particular, the γ-ray-induced graft copolimerization of EM with AAc in N-methyl-2-pyrrolodinone (NMP)/water co-solvent readily gave rise to a water soluble, self-protonated and semi-conductive EM, which could be cast into free-standing films from an aqueous solution.