Continuous RAFT miniemulsion polymerization of styrene in a train of CSTRs

Reversible addition fragmentation transfer (RAFT) miniemulsion polymerization of styrene in a train of continuous stirred tank reactors (CSTRs) is described. It is observed that the polydispersity of the polymer decreases as the number of CSTRs in the train increases, as has been derived theoretically. Furthermore, the CSTRs do not reach steady state, which has been attributed to, at least in part, slow oligomerization of monomer and capping by RAFT agent in the feed. Particle nucleation in a CSTR is found to be less effective than in a batch reactor. This is attributed to a dry-out mechanism, which is observed to be more significant in a CSTR than in batch, leading to a nongrowing population of dormant chains. Experimental evidence for the presence of this nongrowing population is also provided. (C) 2005 American Institute of Chemical Engineers.