Cross-linking conducting polythiophene with yellow-green light-emitting properties and good thermal stability via free radical polymerization and electropolymerization

The electropolymerization and deposition of conjugated polythiophene network films on planar indium tin oxide electrode surfaces were described. The precursor polymer, a polymethacrylate functionalized with thiophene, poly[3-(hexyl methacrylate)]thiophene (P3HMAT), was synthesized and then electropolymerized on ITO substrates in boron trifluoride diethyl etherate (BFEE)/CH2Cl2 (v/v = 6:4) binary solution system, resulting in poly{poly[3-(hexyl methacrylate)]thiophene} (PP3HMAT). The possibility of inter- and intramolecular polymerization resulted in a cross-linking conjugated network microstructure. The fluorescence spectra indicated that PP3HMAT films can be used as yellow-green-light emitters even they could not be dissolved in common solvents. The thermal analyses demonstrated that PP3HMAT has good thermal stability. In addition, the molecular weight and distribution of P3HMAT were characterized by GPC, and the molecular structures of the monomer and the polymers were characterized by 1H NMR and FTIR, and optical properties of the monomer and polymers were characterized by UV–vis spectroscopy.