Atom-transfer radical batch and semibatch polymerization of styrene

Batch and semibatch styrene polymerizations are carried out using a heterogeneous ATRP catalyst system that provides excellent molecular-weight control. The observed initiator efficiency is lower for semibatch operation due to the high initiator concentrations required to make a low-MW polymer. Experiments verified that the insoluble metal complex does not participate in the polymerization and that Cu(I) solubility is an order of magnitude higher than that of Cu(II). A mechanistic model, using kinetic coefficients from literature and the solubility data from this study, provides a good representation of the experimental results.