Enabling Oxygen–Sulfur Exchange Reaction to Produce Semicrystalline Copolymers from Carbon Disulfide and Ethylene Oxide

This work describes the first example of semicrystalline poly(thiocarbonate)s from carbon disulfide (CS2) and ethylene oxide (EO), two mass producible low‐cost monomers. Lewis acid/base pairs (LPs) exhibit high activity (EO conversion up to >99%, 8 h) in catalyzing the copolymerization under low Lewis pair/monomer ratio of 1:1500. Oxygen–sulfur exchange reaction (O–S ER) during the copolymerization of CS2 and EO, the generation and mutual copolymerization with COS, CO2, and episulfide, is harnessed to introduce crystallizable segments [SC(O)O and SC(S)S] in the copolymer. The type of Lewis base is found to have a great impact on the chain microstructure and the crystalline properties. The formed copolymers with melting point from 117.7 to 245.3 °C are obtained. The maximum crystallinity is estimated to be 78% based on the powder wide‐angle X‐ray diffraction pattern. This work provides a general method to prepare semicrystalline sulfur‐containing polymers. Semicrystalline poly(thiocarbonate)s from ethylene oxide and carbon disulfide are synthesized with catalysis of organic Lewis pair. The oxygen–sulfur exchange reaction during the copolymerization controlled by the type of Lewis base and the reaction conditions is harnessed to produce the polythiocarbonate with various chain microstructure and the crystalline properties.