Economical sulfur conversion to polythioamides through multicomponent polymerizations of sulfur, dibromides, and diamines

Polythioamides, as a new group of sulfur-containing polymer materials with unique optical properties and metal coordination ability, have attracted increasing research interest recently. Their cost-effective synthetic approaches and potential scale up of production are highly desired. In this work, the efficient N-methylpiperidine (NMP)-assisted reaction of elemental sulfur, benzyl bromide, and amine was demonstrated to produce thioamides in 85–89% yields. The NMP-assisted multicomponent polymerization (MCP) of elemental sulfur, dibromides, and diamines was hence developed to provide economical access to a series of polythioamides with high molecular weights (M_w up to 16 900 g mol⁻¹) and excellent yields (up to 97%). The MCP featured high efficiency, mild conditions in air, a simple procedure, and robustness, and all three monomers were readily available commercial raw materials, enabling the 10-gram-scale synthesis of these polythioamides. The polythioamides exhibited high glass transition temperatures and high refractive indices of 1.7135–1.7771 at 589 nm, and could be used to enrich Au³⁺ from aqueous solutions with high enrichment capacity (up to 495 mg Au³⁺ per g), high selectivity and efficiency, demonstrating their potential economic value. The MCP of elemental sulfur, dibromides, and diamines, hence, offers a versatile synthetic strategy to produce cost-effective and sustainable functional polythioamides, accelerating the development of profitable polymer materials originating from sulfur.