Cyclization Polymerization of Elemental Sulfur and Diisocyanate: New Polymerization Toward High-Performance Polymer

The development of polymer materials heavily relies on new polymerization reactions. Herein, we report the discovery of cyclization polymerization of element sulfur (S₈) and aliphatic diisocyanate at room temperature with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) organic base as the catalyst, where the two monomers are covalently linked via the formation of thiadiazolidinone (TDZD) or a cyclic isocyanurate ring. The polymer of S₈ and 1,6-diisocyanatohexane (HDI) exhibits remarkable thermal stability and mechanical properties. Particularly, it has exceptionally high adhesion to various substrates in air or under water, e.g., the underwater adhesion strength is as high as ∼26.5 MPa for poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) and ∼2.3 MPa for poly(tetrafluoroethylene) (Teflon). The cyclization polymerization provides the basis for the synthesis of high-performance polymers with elemental sulfur.