Modulating Polymerization Behaviors of Ether-Ester Monomers and Physicochemical Properties of Poly(ether-alt-ester)s by Heteroatom Substitutions

The design of cyclic monomers is crucial for the development of polymers with ideal thermal and mechanical properties by ring-opening polymerization. Herein, we provide a systematic investigation into the thio-modification effects on the polymerization behavior of cyclic ether-ester monomers and the final properties of the corresponding poly(ether-alt-ester)s. The position of thio-modification significantly affected the polymerization thermodynamics and thus could regulate the ceiling temperature (T-c). O-to-S substitutions in the monomer ' s ether/ester sites would increase the monomer ' s alpha-H acidity, and the catalytic system strictly determined the chain initiation process as well as the chain-end groups. Density functional theory calculations and experimental studies revealed that O-to-S substitutions at the ester site would significantly accelerate the polymerization under the same conditions, thanks to the high reactivity of the thioester group and strong nucleophilicity of the chain end. The resulting poly(ether-alt-ester)s exhibited crystallinity, precisely tunable physicochemical properties, high recyclability, and high-density polyethylene-like mechanical properties, which exemplifies the potential of heteroatom modification in modulating the poly(ether-alt-ester)' s properties. This detailed investigation of structure-(de)polymerizability and structure-property relationships will inspire future monomer design toward poly(ether-alt-ester)s with high performance.