Dual Roles of a Xanthate as a Radical Source and Chain Transfer Agent in the Photoinitiated RAFT Polymerization of Vinyl Acetate

A high level of control over the photoinitiated RAFT polymerization of vinyl acetate (VAc) was achieved using a specifically designed xanthate, <i>S</i>-2-cyano-2-propyl-<i>O</i>-ethyl xanthate (CPEC), which acted as a radical source and a chain transfer agent simultaneously. Unlike other RAFT processes, the present system did not use any additional radical initiator, while achieving greater control over the polymerization than the photoiniferter process. The molecular weight of the resulting polymer could be modulated by changing the initial [VAc]₀/[CPEC]₀ ratio, but the control over the polymerization was lost with a very low initial [VAc]₀/[CPEC]₀ ratio. The intensity of UV irradiation affected the polymerization by reducing the induction period and increasing the rate of polymerization but did not affect the molecular weight of the resulting polymer