Synthesis and Interfacial Characterization of Graft and Random Copolymers of Styrene and 2-Hydroxyethyl Methacrylate

Abstract

Polystyrene (PSt) macromonomers with methacrylate end-groups (M1) were copolymerized with 2-hydroxyethyl methacrylate (HEMA, M2) to give amphiphilic graft copolymers with PSt branches. The monomer reactivity ratio of HEMA was estimated as r2=1.7±0.4. The 1H NMR spectrum of a graft copolymer in methanol revealed a micelle formation with a PSt core, while chloroform caused the formation of a reversed micelle with a PHEMA core. The contact angle of water on polymer films suggested that the PSt segments generally dominate the surface properties of graft copolymers, independent of a composition above 15 wt% PSt. In contrast, the random copolymers of St and HEMA showed results as expected for a single-phase structure, both by 1H NMR and contact angle.