Facile Synthesis of Well‐Defined Branched Sulfur‐Containing Copolymers: One‐Pot Copolymerization of Carbonyl Sulfide and Epoxide

Topological polymers possess many advantages over linear polymers. However, when it comes to the poly(monothiocarbonate)s, no topological polymers have been reported. Described herein is a facile and efficient approach for synthesizing well‐defined branched poly(monothiocarbonate)s in a “grafting through” manner by copolymerizing carbonyl sulfide (COS) with epichlorohydrin (ECH), where the side‐chain forms in situ. The lengths of the side‐chains are tunable based on reaction temperatures. More importantly, enhancement in thermal properties of the branched copolymer was observed, as the T_g value increased by 22 °C, compared to the linear analogues. When chiral ECH was utilized, semicrystalline branched poly(monothiocarbonate)s were accessible with a T_m value of 112 °C, which is 40 °C higher than that of the corresponding linear poly(monothiocarbonate)s. The strategy presented herein for synthesizing branched polymers provides efficient and concise access to topological polymers.