Cascade Initiation of Ring Opening Polymerization for Dynamic Covalent Poly(disulfide)s: One-Step Double Modification and Copoly(disulfide) Synthesis by Living Polymerization

The dynamicity and recyclability of a material are the chemical bases of sustainable future smart materials. In this context, the poly(disulfide)s of 1,2-dithiolane are a very significant class of polymers due to the presence of dynamic covalent disulfide bonds in the main-chain polymer. Here we reported an amine-activated cascade initiation of thiolate-induced ring opening polymerization (ROP) of the 1,2-dithiolane ring to synthesize functional poly(disulfide)s at room temperature and under an open-air condition. In situ generation of the thiolate initiator by the reaction of the thiolactone ring and amine, stabilization, and use of the phenyl isocyanate terminator enable us to perform the polymerization in a controlled manner. Additionally, in situ, one-step, dual modification at the polymer chain end by varying amine and thiolate allowed us to access a variety of functional poly(disulfide)s. The primary amine is found to be a more effective activator compared to the secondary amine. We also demonstrated the living nature of the poly(disulfide)s and synthesized tailor-made copoly(disulfide)s. We believe that the ROP of poly(disulfide)s activated by amine is the first report in the literature where we can use a library of amines to functionalize poly(disulfide)s and access diverse structures of polymers. This methodology establishes a versatile platform and opens up enormous opportunities for the synthesis of a variety of dynamic polymers.