One-pot photoinduced synthesis of conductive polythiophene-epoxy network films

In this paper, we describe a novel methodology for fabricating conductive epoxy-polythiophene network films by simultaneous photoinduced step-growth and cationic ring opening polymerization processes. For this purpose, formulations containing a bifunctional epoxy monomer, namely 1,6-hexanediol diglycidyl ether (HDGE) and different amount of thiophene ranged from 0 to 50 wt% in the presence of an iodonium salt, namely (4-methylphenyl)[4-(2-methylpropyl) phenyl]-iodonium, hexafluorophosphate were irradiated under UV light. In the process, while polythiophene was formed through electron transfer reaction between photochemically formed phenyliodinium radical cations followed by proton release and coupling reactions, cationic ring opening polymerization of HDGE initiated by the liberated protons resulted in the formation of epoxy network. Conductivity of the obtained films was evaluated by surface resistivity measurements by means of a standard two-point micro-contact method before and after iodine doping. It was found that iodine doping provided a significant improvement in the surface conductivity. This work conclusively provides a new approach for bonding conducting polymers with epoxy-based network films via photoinduced electron transfer reactions in a simple, fast, and efficient approach of importance in electronic and other applications.