Vapor polymerization deposition of polyimide thin films having oligothiophene segments in the main chain

New polyimide thin films that have oligothiophene segments in the main chain have been fabricated in the form of thin films by a vapor deposition polymerization technique. First, polyamide acid (precursor of polyimide) thin film was prepared by the addition reaction between pyromellitic dianhydride and α,ω-bis(aminomethyl)oligothiophene whose degree of polymerization spans dimer to tetramer. Next, the polyamide acid was imidized to polyimide film by curing (annealing). The spectroscopic data indicate that the reaction occurs successfully and that the thin films have the oligothiophene backbone. The films of high quality are uniform and transparent. The curing process causes reorientation of the polymer chains. X-ray diffraction measurement indicates that the morphology of the fully imidized films shows layered structure and that the molecular axis is almost perpendicular to the substrate plane like the vapor deposited films of the monomers.