The preparation of polythioamides through multicomponent polymerization involving elemental sulfur possesses several advantages such as simple procedure, wide monomer scope, catalyst free, and high atom economy. However, elevated temperature in previous work was indispensable on the synthesis of polythioamides. Herein, we designed highly active alkyne activated by electron-withdrawing unit to increase the reaction efficiency and reduce the polymerization temperature. Multicomponent polymerization of elemental sulfur, pyridyl-activated alkyne ,and aliphatic diamine was developed to afford different polythioamides with clear structures, high yield (98%) and high molecular weight (Mw = 35 400 g/mol) at room temperature without any catalyst. With the reaction temperature slightly increased to 40 °C, the molecular weight increased to 95 100 g/mol in high yield (98%), while the polythioamide with relatively low molecular weight (Mw = 59 100 g/mol) and yield (84%) synthesized from non-activated 1,3-diethynylbenzene required higher monomer concentration at higher temperature of 90 oC. Besides, with the introduction of pyridyl group into polymer backbone, the polythioamide obtained a higher enrichment efficiency with a lower mass ratio of polymer to mercury ions, owing to the coordination property of the pyridine group. Interestingly, the emission of both polythioamides and model compounds have blue shifts after being irradiated with 365 nm ultraviolet light for 30 minutes, which is a supplement and exploration on the luminescent property of the polythioamide systems.

Room temperature multicomponent polymerization of elemental sulfur, pyridyl-activated alkyne and aliphatic amines

ACS Spring 2022

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