Preparation of conductive polybenzoxazines by oxidative polymerization

Soluble and thermally curable conducting high molecular weight polybenzoxazine precursors were prepared by oxidative polymerization 3-phenyl-3,4-dihydro2H-benzo[e][1,3] oxazine (P-a) alone and in the presence of thiophene (Th) with eeric ammonium nitrate in acetonitrile. The structure of the precursors was confirmed by FTIR, ¹H NMR, and DSC measurements, indicating the presence of a cyclic benzoxazine structure, together with small but varying amount of a ring opened phenolic structure. The resulting polymers exhibit conductivities around 10^-2 S cm^-1 and undergo thermal curing at various temperatures. Attempts to copolymerize P-a with another electroactive monomer, pyrrole (Py), by a similar redox process were unsuccessful, which was attributed to the unfavourable oxidation potential of Py. The cured products exhibited high thermal stability but lower conductivity, than those of the precursors.