Straightforward synthesis of model polystyrene-block-poly(vinyl alcohol) diblock polymers

Abstract

We report the synthesis and characterization of well-defined polystyrene-block-poly(vinyl alcohol) (PS-b-PVA) polymers and the corresponding polystyrene-block-poly(vinyl acetate) (PS-b-PVAc) precursors using a combination of atom transfer radical polymerization (ATRP), copper-catalyzed azide alkyne cycloaddition reaction, and reversible addition–fragmentation chain transfer (RAFT) polymerization. Bromine end-functional polystyrene was first prepared using activators regenerated by electron transfer ATRP. A xanthate mediated macro chain transfer agent carrying a triazole-based R-group was achieved by the CuAAC reaction between the corresponding azide-functional polystyrene and an alkyne functional O-ethyl S-prop-2-ynyl carbonodithioate. PS-b-PVAc diblock polymers were synthesized by RAFT polymerization using the triazole-based macro-CTA. The formation of well-defined PS-b-PVA diblock polymers was followed by ¹H nuclear magnetic resonance spectroscopy, infrared spectroscopy and size-exclusion chromatography. Thermal properties of the diblock polymer were analyzed by thermal gravimetric analysis and differential scanning calorimetry. The PVAc segments were hydrolyzed to give the corresponding PS-b-PVA block polymers. The morphology of the polymers was investigated by grazing-incidence small-angle scattering as well as atomic force microscopy.