Polyaniline: Inter-Relationship between Ultra-Structure and Properties

Abstract : The conductivity (doped form), degree of crystallinity, tensile strength, solubility and swellability (as a gel) of polyaniline (emeraldine oxidation state) is found to be greatly dependent on the past chemical and/or mechanical history of the polymer which significantly affects the ultrastructure of the material. The conductivity and tensile strength of polyaniline films and fibers can be greatly enhanced by stretch orientation which is also accompanied by a monotonic increase in crystallinity. The solubility of the emeraldine base in NMP is greatly decreased as the degree of crystallinity is increased. The conductivity shows relatively little dependency on molecular weight as compared to crystallinity; it first rises monotonically with increase in molecular weight and then remains essentially independent of molecular weight. Gels of oriented emeraldine base exhibit a remarkable anisotropic swelling in NMP and in mixtures of NMP/CH3OH.