Episullide polymerization offers a number of features that are uncommon in other ring-opening anionic mechanisms. Besides the negligible sensitivity to water, the most distinctive and novel one is likely to be the role of disulfides, which may act both at the levels of chain transfer and end-capping, producing polymers that feature both terminal and internal disulfides. In this article, we have qualitatively studied the kinetics of chain transfer and measured the thiolate-disulfide exchange equilibrium constants. (c) 2008 Wiley Periodicals, Inc.