Ring-Opening Polymerization of Aromatic 6-Membered Cyclic Disulfide and Characterization of the Polymer

Synthesis and characterization of polymers obtained from polymerization of 1,4-dihydro-2,3-benzodithine (XDS) were investigated. The polymerization of XDS proceeded at reaction temperatures above the melting points of XDS to give polymers, and the molecular weight, which determined by GPC was high. From the structural analysis of poly(XDS), the polymer was found to have cyclic structure, in contrast to their linear polymer (poly(XDS-XDT) obtained from the polymerization of XDS in the presence of chain transfer thiol compounds such as alpha,alpha'-mercapto-o-xylene (XDT). From TGA and DSC measurements, poly(XDS) with benzene rings in the main chain is more thermal stable than the polymer obtained from the polymerization of 1,2-dithiane (DT). From dynamic viscoclastic measurements, poly(XDS) showed a rubbery plateau under the molten state even though poly(XDS) has no crosslinking system. The difference in solubility between poly(XDS) and poly(XDS-XDT) was also observed. On the basis of the polymer characterizations, it may be concluded that the poly(XDS) obtained from thermal ring-opening polymerization of XDS includes a polycatenane structure.