Self-switchable polymerization is an attractive strategy for precisely controlling the microstructures and monomer sequences of polymers. To date, catalysts for the polymerization are generally limited to metal complex catalysts and some organocatalysts. In this article, we report that simple, inexpensive, and environmentally benign alkali metal carboxylate catalysts smartly switch between the ring-opening alternating copolymerization of epoxides with cyclic anhydrides and the ring-opening polymerization of cyclic esters to create a single synthetic step and thus achieve sequence-controlled multiblock polyesters. This polymerization system shows extremely high effectiveness and versatility for different combinations of epoxides, cyclic anhydrides, cyclic esters, and initiators. As a result, various types of complex block copolymers, such as AB diblocks, BAB triblocks, star copolymers, hyperbranched copolymers, and CAB triblocks, can be simply prepared and postpolymerization modification can be performed. As a proof of concept, polyester-based elastomers and adhesives were successfully synthesized via one-step procedures by reasonably designing the monomer structures of triblock copolymers, showing great potential for industrial applications of polyesters.

The alternating copolymer of lactic acid and glycolic acid (PLGA) is a highly promising next generation biodegradable material for biomedical and pharmaceutical applications due to its uniform degradation behaviors in...

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Trimethyl glycine (TMG), a natural product found in plants as well as in humans, was demonstrated to be an efficient catalyst for the ring-opening polymerization (ROP) of cyclic carbonate, enabling the environmentally benign synthesis of aliphatic polycarbonate (APC). The ROP of trimethylene carbonate (TMC) using TMG proceeded under the bulk condition at 70 °C to give poly­(trimethylene carbonate), possessing controlled molecular weight (∼4000) and low dispersity (∼1.22). The results of a matrix-assisted laser desorption/ionization time-of-flight mass spectral analysis and a chain extension experiment confirmed the controlled/living nature of the present ROP system, where side reactions, such as inter- and intramolecular transesterifications, were minimized during the polymerization. The screening of TMG analogues as a catalyst for ROP revealed that the combination of the carboxylate and quaternary ammonium moieties in TMG is an essential structural requirement. The Fourier transform infrared analyses of TMC and alcohol initiator in the presence/absence of TMG confirmed the biactivation property of the TMG. End-functionalized APCs were obtained using alcohol initiators bearing clickable functionalities, such as azido and ethynyl groups. Furthermore, we demonstrated the synthesis of APC-diol and -triol, which can be used as prepolymers for APC-based polyurethane.