Syntheses and interfacial characterization of graft copolymers from styrene and 2-hydroxyethyl methacrylate that comprise either trunks or branches

Abstract

Polystyrene (PS) and poly(2-hydroxyethyl methacrylate) (PHEMA) macromonomers with either p-vinylbenzyl or methacrylate end groups were prepared by living anionic polymerizations of styrene and 2-(trimethylsilyloxy)ethyl methacrylate, respectively, followed by appropriate end-capping. They were radically copolymerized with 2-hydroxyethyl methacrylate and styrene, respectively, to afford PS-g-PHEMA and PHEMA-g-PS, having PS trunks with PHEMA branches or the reverse architecture. 1H NMR spectra of the graft copolymers in deuterated methanol showed their micelle formation with PS and PHEMA chains as the core and the shell, respectively. In chloroform the reverse micelles were observed. Contact angle measurements of water on the graft copolymer films revealed that PS chains were generally dominant on the free surface. The films either cast from methanol or after immersion into water, however, were apparently wettable, indicating dominant PHEMA chains on the surface. Keywords: styrene, 2-hydroxyethyl methacrylate, graft copolymer, micelle formation, wettability.