ATRP of POSS Monomers Revisited: Toward High-Molecular Weight Methacrylate–POSS (Co)Polymers

Abstract

For the first time, ATRP was successfully employed for homopolymerization of a commercial methacrylate-functionalized polyhedral oligomeric silsesquioxane (POSS) monomer, iBuPOSSMA, to high molecular weights. It was found that iBuPOSSMA has a low ceiling temperature (Tc); therefore, low temperatures and/or high initial monomer concentrations need to be used in order to avoid low degrees of polymerization that had been observed previously. The values of Tc, as well as of the polymerization enthalpy ΔHp and entropy ΔSp were determined to be 130 °C (at [M]0 = 1 M), −41 kJ mol–1, and −101 J mol–1 K–1, respectively. Under optimized conditions, poly(iBuPOSSMA) homopolymers having low dispersity and high Mn, ranging from 23 000 to 460 000, were obtained in a well-controlled ATRP process. Moreover, various block copolymers having high-Mn poly(iBuPOSSMA) blocks were prepared by copolymerization of iBuPOSSMA with methyl methacrylate and styrene.