Studies on chemically synthesized soluble acrylic acid doped polyaniline

Abstract

Polyaniline doped with acrylic acid was synthesized by using chemical oxidative polymerization method. This is a new polymerization method for the direct synthesis of the emeraldine salt of polyaniline that is soluble in common organic solvents. The results are discussed with reference to HCl doped polyaniline. It is observed that acrylic acid doped polymer is comparatively more soluble in m-cresol and NMP than that doped with HCl in its salt form. UV–VIS spectra of acrylic acid doped polyaniline reveals the presence of a free carrier tail characteristic of an extended coil conformation at higher wavelength along with a sharp polaronic peak in m-cresol as a solvent. Whereas, in N-methyl pyrrolidinone (NMP) the emeraldine base form is predominant along with a sharp peak at ∼320 nm. Wide angle X-ray studies show that polyaniline doped with acrylic acid exhibits higher crystallinity indicating enhanced polymer sub-chain alignment. This is further manifested by the FT-IR studies. The broad and intense bands at ∼3400–3300 cm −1 and 1150–1120 cm −1 in acrylic acid doped polyaniline account for the higher degree of doping. These results are well supported by the conductivity measurements, where the conductivity of acrylic acid doped polymer is greater than that doped with HCl.