Catalyst-Free Click Polymerization of Thiol and Activated Internal Alkynes: A Facile Strategy toward Functional Poly(β-thioacrylate)s

Thiol–yne click polymerizations have become efficient synthetic tools for the construction of linear and hyperbranched polysulfides with advanced functionalities. However, the polymerization reaction of internal alkynes and thiols has been rarely utilized to prepare functional polymers. In this work, a catalyst-free click polymerization between activated internal alkyne and thiol was developed. The polymerizations of 4,4′-thiodibenzenethiol (1) with dibutynoates (2) and diphenylpropiolates (3) were performed in N,N-dimethylformamide (DMF) at 60 °C, producing poly(β-thioacrylate)s (PTAs) with high molecular weights (Mw up to 50300) and high stereoregularities (Z content up to 84%) in high yields (up to 91%). The click polymerization can be conducted smoothly in an open atmosphere without protection against moisture and oxygen. The resultant PTAs possess good solubility in common organic solvents and high optical transparency. Thanks to the high contents of sulfur atoms, ester groups, and aromatic rings in the polymers, their thin films show high refractive indices (n > 1.63) in the wavelength region of 400–1700 nm. Moreover, the PTAs containing tetraphenylethene moieties exhibit aggregation-induced emission characteristics.