EXPERIMENTAL-EVIDENCE FOR HYDROGEN-BONDING IN POLYANILINE - MECHANISMOF AGGREGATE FORMATION AND DEPENDENCY ON OXIDATION-STATE

Aggregation in the nondoped polyaniline, emeraldine base (EB), as obse rved by GPC in a N-methyl-2-pyrrolidinone (NMP) solution, was found to be closely related to the fraction of the imine nitrogen atoms in the nondoped polymer, i.e., to the oxidation state of the polymer. As EB was reduced to leucoemeraldine base (LEE), the degree of aggregation w as significantly reduced. The results of gel permeation chromatography (GPC) and infrared studies suggest that the aggregation of the polyme r is due to interchain hydrogen bonding between the imine and amine ni trogen sites on adjacent polymer molecules. The degree of hydrogen bon ding and, thus, aggregation found in the polymer is greatly affected b y solvents, LiCl, and the oxidation state the polymer.