Trimethylene sulfide is primarily used as a monomer in the synthesis of polythioethers, which are sulfur-containing polymers known for their flexibility and chemical resistance. These polymers find application in specialty elastomers and sealants, particularly in environments requiring resistance to fuels and organic solvents. It is also explored in the development of functional materials for lithium-sulfur batteries due to the compound’s ability to form conductive and stable sulfur-rich networks. Additionally, trimethylene sulfide serves as an intermediate in organic synthesis, enabling the construction of heterocyclic compounds and bioactive molecules in pharmaceutical research. Its ring-opening reactivity makes it valuable in controlled polymerization techniques for designing advanced polymeric architectures.