Catalyst-Free Thiol–Yne Click Polymerization: A Powerful and Facile Tool for Preparation of Functional Poly(vinylene sulfide)s

The "thio-click" polymerization is a well-expanded concept of click polymerization. Among the click polymerizations, the thiol–yne click polymerization is less developed and still in its infancy stage. In general, UV light, elevated temperature, amine, or transition metal complexes is needed to catalyze the thiol–yne click polymerization, which greatly complicates the experimental operation and limits its application. In this work, a facile and powerful thiol–yne click polymerization was developed, which could be carried out under very mild conditions without using external catalyst. Simply mixing the aromatic diynes (1a–1e) and dithiols (2–4) with equivalent molar ratio in THF at 30 °C will readily produce soluble and regioregular functional poly(vinylene sulfide)s (PIa–PIe, PII, and PIII) with high molecular weights (Mw up to 85 200) in excellent yields (up to 97%) after as short as 2 h. Furthermore, no double addition product of an ethynyl group was found. This catalyst-free thiol–yne click polymerization has remarkably simplified the reaction conditions and will facilitate the preparation of functional materials applied in diverse areas.