Cyclic disulfides, ring-opening polymerization

Sulfur is an interesting atom because of the specific characteristics of the simple substance and compounds containing sulfur. Further, their functions are indispensable for current technologies. Studies on sulfur compounds are valuable not only in chemistry but also in biochemistry as well. Many cyclic monomers containing sulfur such as cyclic disulfides, thiiranes, thietanes, and arene dithiols were reported to form cyclic polymers by the ring-opening polymerization. The natural source of cyclic polymers is believed to be liquid, elemental sulfur [177-179]. 

A five-membered cyclic vinylsitlfone underwent the complete R-ROP to afford the polysitlfone with double bonds in the main chain, whereas the R-ROP of a six-membered one was accompanied by vinyl polymerization (5, 46). A six-membered vinyldisitlfone coitld imdergo the R-ROP to afford the complete ring opened polymer (3, 47). A polysnlfone with exo-methylene groups in the polymer backbone could be also prepared by the R-ROP of cyclic allylic disulfides followed by the oxidation (48). 

A new approach to the synthesis of aromatic polysulfides and polydisulfides consists of the preparation of polydisperse cyclic oligosulfides (or disulfides) followed by ringopening polymerization. In several publications [358-365] a Canadian research group has elaborated and described this approach in much detail. This approach may be subdivided into two classes of cycles and ring opening mechanisms ... 

---