Reversible addition fragmentation chain transfer (RAFT) mediated polymerization of N-vinylpyrrolidone: RAFT agent design

A selection of seven O-ethyl xanthates with different R groups were tested for their ability to control the polymerization of N-vinylpyrrolidone (NVP). Quantification of the species involved in the initialization step was achieved via in situ 1H-NMR spectroscopy by using a high concentration of xanthate compared to typical polymerization concentrations. The results pointed at 3 different initialization behaviors, namely selective, poorly selective and selective but slow initialization. The selectivity and length of the initialization period were used as criteria to classify the different R groups with respect to NVP. The classification obtained is valuable to the design of an optimized RAFT agent for the preparation of poly(N-vinylpyrrolidone) with narrow molar mass distribution and well-defined endgroups.