Radical telomerization of vinyl acetate with chloroform. Application to the synthesis of poly(vinyl acetate)-block-polystyrene copolymers by consecutive telomerization and atom transfer radical polymerization

Abstract

This paper demonstrates that radical telomerization and atom transfer radical polymerization (ATRP) can be combined in a two-step procedure to prepare poly-(vinyl acetate)-block-polystyrene (PVOAc-b-PSt) diblock copolymers. The first step consists in telomerizing VOAc with chloroform, leading to trichloromethyl-terminated VOAc telomers CCl3(VOAc)nH. A detailed 1H NMR analysis shows that nearly pure telomer structures are obtained over a broad range of DPn values (up to at least 60 units). When ATRP of styrene is initiated with a model telomer adduct (CCl3CH2CH2OAc), molecular weights increase linearly with monomer conversion and match theoretical values. Moreover, polydispersities are consistently low (1.22 < Mw/Mn < 1.38) throughout polymerization. Similarly, VOAc telomers (DPn = 9 and 62) are good ATRP macroinitiators. The high purity of the resulting diblock copolymers is confirmed by GPC using RI/UV dual detection.