Polymerizations with elemental sulfur: A novel route to high sulfur content polymers for sustainability, energy and defense

Recent developments in the polymerizations of elemental sulfur (S8) to prepare high sulfur content polymers are reviewed. While the homopolymerization of S8 via ring-opening processes to prepare high molar mass polymeric sulfur has long been known, this form of polymeric sulfur is chemically unstable and depolymerizes back to S8. In the current report, we discuss the background into the production of sulfur via petroleum refining and the challenges associated with utilizing S8 as a chemical reagent for materials synthesis. To circumvent these long standing challenges in working with sulfur, the use of S8 as a reaction medium and comonomer in a process termed, inverse vulcanization, was developed to prepare chemically stable and processable sulfur copolymers. Furthermore, access to polymeric materials with a very high content of sulfur–sulfur (SS) bonds enabled for the first time the creation of materials with useful (electro)chemical and optical properties which are reviewed for use in Li–S batteries, IR imaging technology and self-healing materials.