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 (S-S) 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.