Solvent and Water Enabled Control of Alkyne-Base Polymerization Triggered by a Spontaneous Imine-Yne Click Reaction

The control of the polymer structure is a pivotal factor in imparting a wide range of desirable properties to polymers. However, existing methods often entail harsh conditions and laborious procedures. In this study, we demonstrate that solvent and water play a crucial role in the facile regulation of cyclic imidazolidine and linear dienamine units in the polymer chains produced by the facile polymerization of imidazolines and ester alkynes, which was triggered by the spontaneous imine-yne click reaction. Notably, when carried out in acetonitrile, the yielded polymers predominantly feature cyclic imidazolidine structures (up to 96%), whereas those synthesized in chloroform in the presence of water are predominantly characterized by linear dienamine structures (up to 91%). These structural variances give rise to diverse properties in the polymers, including variations in glass transition temperatures, Raman signals, nontraditional luminescence, refractive indices, etc. Moreover, the reaction mechanism was unambiguously proposed based on model reaction studies, shedding light on the underlying chemical processes driving these distinct results. The ability to control polymer structure through solvents and water offers a promising avenue for tailoring polymer properties, unlocking new opportunities for advanced materials design.