Precisely Alternating Copolymerization of Episulfides and Isothiocyanates: A Practical Route to Construct Sulfur-Rich Polymers.

The development of a controlled and reliable method to construct well-defined sulfur-containing polymers has sparked great interest in polymer science. Herein, we present the trial on the copolymerization of isothiocyanates with episulfides in the presence of organic onium salts, which provides direct access to a class of sulfur-rich polymers. This methodology has combined advantages of simple operation, no metals, mild conditions (25-100 °C), controlled polymerization performance ( > 10 g mol, < 1.3), and high reactivity (turnover frequency over 1000 h). The metal-free feature and versatility of the easily accessible monomers, along with fine adjustment of the final properties enable this strategy to be a feasible approach to produce sulfur-rich polymers (16 examples).