(S)‐2‐(ethyl propionate)‐(O‐ethyl xanthate)‐ and (S)‐2‐(Ethyl isobutyrate)‐(O‐ethyl xanthate)‐mediated RAFT polymerization of vinyl acetate

Abstract

Abstract(S)‐2‐(Ethyl propionate)‐(O‐ethyl xanthate) (X1) and (S)‐2‐(Ethyl isobutyrate)‐(O‐ethyl xanthate) (X2) were used as the reversible addition‐fragmentation chain transfer (RAFT) agents for the radical polymerization of vinyl acetate (VAc). The former showed the better chain transfer ability in the polymerization at 60°C. Kinetic study with both RAFT agents showed pseudo‐first order kinetics up to around 85% monomer conversion. Molecular weight of the resulting polymer increased linearly with increase in the monomer conversion up to around 85%. The observed molecular weights calculated from 1H‐NMR spectrum [Mn(NMR)] are close to the corresponding theoretical molecular weights [Mn(theor)]. The corresponding polydispersity index (PDI) of the resulting polymers remained almost constant at around 1.2 up to ∼ 65% monomer conversion and then increased gradually with the further increase in the monomer conversion. Chain‐end analysis of the resulting polymers by 1H‐NMR showed clearly that polymerization started with the radical forming out of the xanthate mediator. The negligible homo‐chain extension and the hetero‐chain extension involving synthesis of poly(VAc)‐b‐poly(NVP) diblock copolymer were occurred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012