Graft copolymerization of thiophene onto polystyrene synthesized via nitroxide-mediated polymerization and its polymer - clay nanocomposite

Abstract

A new strategy for graft copolymerization of thiophene onto a polystyrene (PSt) backbone by a multi-step process is suggested and the effects of an organoclay on the final properties of the graft copolymer sample are described. For this purpose, first poly(styrene-co-4-chloromethyl styrene) [P(St-co-CMSt)] was synthesized via nitroxide-mediated polymerization. Afterwards, the chlorine groups of P(St-co-CMSt) were converted to thiophene groups using the Kumada cross-coupling reaction and thiophene-functionalized PSt multicenter macromonomer (ThPStM) was synthesized. The graft copolymerization of thiophene monomers onto PSt was initiated by oxidized thiophene groups in the PSt chains after addition of ferric chloride (FeCl3), an oxidative catalyst for polythiophene synthesis, and FeCl3-doped polythiophene was chemically grafted onto PSt chains via oxidation polymerization. The graft copolymer obtained was characterized by H-1 NMR and Fourier transform infrared spectroscopy, and its electroactivity behavior was verified under cyclic voltammetric conditions. Finally, PSt-g-PTh/montmorillonite nanocomposite was prepared by a solution intercalation method. The level of dispersion of organoclay and the microstructure of the resulting nanocomposite were probed by means of XRD and transmission electron microscopy. It was found that the addition of only a small amount of organoclay (5wt%) was enough to improve the thermal stabilities of the nanocomposite.(c) 2013 Society of Chemical Industry