Elemental Sulfur as an Initiator for the Synthesis of Sulfur-Containing Epoxy Resins Through Anionic Polymerization

Elemental sulfur has been applied as feedstock for the synthesis of sulfur-rich polymers through radical-based reaction mechanisms in inverse vulcanization processes. This work demonstrates another reaction route that utilizes elemental sulfur in the synthesis of sulfur-containing epoxy resins through elemental-sulfur-initiated anionic polymerization. First, the reaction mechanism is examined using a model reaction that employs a monofunctional epoxide compound. After that, various multifunctional epoxide compounds are utilized as monomers in the elemental sulfur-initiated anionic polymerization, resulting in the corresponding sulfur-containing epoxy resins. The sulfur content of the resins can be adjusted by varying the amount of elemental sulfur loaded into the reaction systems. The thermal, mechanical, and optical properties of sulfur-containing epoxy resins depend on the sulfur contents and structures of the epoxide monomers. Another role of elemental sulfur has been demonstrated in polymerization chemistry as an effective and convenient approach for the synthesis of sulfur-containing polymers.