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

Full Paper: This paper demonstrates that radical telomerization and atom tr ansfer radical polymerization (ATRP) can be combined in a two-step procedur e to prepare poly(vinyl acetate)-block-polystyrene (PVOAc-b-PSt) diblock co polymers. The first step consists in telomerizing VOAc with chloroform, lea ding to trichloromethyl-terminated VOAc telomers CCl3(VOAc)nH. A detailed H -1 NMR analysis shows that nearly pure telomer structures are obtained over a broad range of <(DP)over bar>(n) values (up to at least 60 units). When ATRP of styrene is initiated with a model telomer adduct (CCl3CH2CH2OAc), m olecular weights increase linearly with monomer conversion and match theore tical values. Moreover, polydispersities are consistently low (1.22<(M) ove r bar(w)/(M) over bar(n)<1.38) throughout polymerization. Similarly, VOAc t elomers (<(DP)over bar>(n) = 9 and 62) are good ATRP macroinitiators. The h igh purity of the resulting diblock copolymers is confirmed by GPC using RI /UV dual detection.