Insights into the Ring-Expansion Polymerization of Thiiranes with 2,4-Thiazolidinedione

The behavior of the ring-expansion homopolymerization of 2 (phenoxymethyl) thiirane (PMT) and propylene sulfide (PS), respectively, with thiazolidine-2,4-dione (TZD) as a cyclic initiator is investigated. The polymerizations show steadily growing molar masses with increasing monomer conversions. In addition, reversible merging reactions between rings are observed, with up to six merged macrocycles formed. The degree of merging is strongly dependent on the initial monomer concentration, whereas temperature has only a small impact. Under optimized conditions, ring poly(PMT) polymer with values of (M) over bar (n) up to 50 250 g mol(-1) and dispersities down to 1.11 can be synthesized. DSC and ESI-MS measurements of the novel ring-poly(PS) prove the formation of ring polymer having topological purity above 95%.