INFLUENCE OF POLYMERIZATION PARAMETERS ON THE MOLECULAR WEIGHT OF POLYANILINE
Maja Vilènik, Majda Žigon*, Marko Zupan, Anton Šebenik Faculty of Chemistry and Chemical Technology, University of Ljubljana, Slovenia *National Institute of Chemistry, Ljubljana, Slovenia
The yield of polymerization and the molecular weight of polyaniline (PAN) were determined in dependence on the ratio of aniline and amoniumperoxodisulphate, temperature, reaction time and pH. It was found that polymerization yield and molecular weight decrease with the increasing ratio oxidant to aniline, pH and temperature. The pH of the reaction mixture rapidly decreases due to the release of proton from 0.80 to 0.35 and during the polymerization slowly increases back to the starting value. The polydispersity is in the wide range and is almost constant with the changing reaction parameters. After the reduction of emeraldine base to leucoemeraldine base, the molecular weight decreases due to the difference in the hydrodinamic volume of quinoid segments in comparision with that of benzenoide, as well as to intermolecular hydrogen bonds between amine and imine groups of benzenoid and quinoide segments of emeraldine base, and the decomposition of the -C-N- bonds after the reduction.