Shuo Yan

The one‐step synthesis of well‐defined telechelic polymers represents a highly attractive approach, providing an efficient alternative to conventional stepwise synthetic protocols. However, achieving such control remains challenging due to the competitive nature of chain propagation and end‐group functionalization, which often leads to uncontrolled chain‐end structures and broad dispersities. Here, we report an alcohol‐mediated self‐switching strategy, in which the dominant chain‐end reaction shifts from propagation to end‐group functionalization upon consumption of one monomer component within a single reaction system. Using epichlorohydrin, a multisite monomer, as a model for the ring‐opening alternating copolymerization with cyclic anhydrides, we obtained well‐defined epoxide‐terminated telechelic polyesters with narrow dispersities ( Đ ∼ 1.1), high end‐group fidelity (>99%), and controllable linear, three‐arm, and four‐arm architectures under alcohol‐mediated conditions. Mechanistic studies reveal that monomer activation and stabilization of the living species through hydrogen‐bonding interactions, combined with the zero‐order kinetics of cyclic anhydride, facilitate rapid propagation while suppressing premature functionalization. Subsequent intramolecular cyclization of β‐chlorohydrin living chain ends, along with proton‐transfer‐induced dehydrochlorination of β‐chlorohydrin dormant chain ends, collectively ensure quantitative epoxide end‐group formation. These results elucidate the catalyst‐like roles of alcohol and establish self‐switching of competing chain‐end reactions as a practical strategy for the direct synthesis of well‐defined telechelic polymers.

The one‐step synthesis of well‐defined telechelic polymers represents a highly attractive approach, providing an efficient alternative to conventional stepwise synthetic protocols. However, achieving such control remains challenging due to the competitive nature of chain propagation and end‐group functionalization, which often leads to uncontrolled chain‐end structures and broad dispersities. Here, we report an alcohol‐mediated self‐switching strategy, in which the dominant chain‐end reaction shifts from propagation to end‐group functionalization upon consumption of one monomer component within a single reaction system. Using epichlorohydrin, a multisite monomer, as a model for the ring‐opening alternating copolymerization with cyclic anhydrides, we obtained well‐defined epoxide‐terminated telechelic polyesters with narrow dispersities ( Đ ∼ 1.1), high end‐group fidelity (>99%), and controllable linear, three‐arm, and four‐arm architectures under alcohol‐mediated conditions. Mechanistic studies reveal that monomer activation and stabilization of the living species through hydrogen‐bonding interactions, combined with the zero‐order kinetics of cyclic anhydride, facilitate rapid propagation while suppressing premature functionalization. Subsequent intramolecular cyclization of β‐chlorohydrin living chain ends, along with proton‐transfer‐induced dehydrochlorination of β‐chlorohydrin dormant chain ends, collectively ensure quantitative epoxide end‐group formation. These results elucidate the catalyst‐like roles of alcohol and establish self‐switching of competing chain‐end reactions as a practical strategy for the direct synthesis of well‐defined telechelic polymers.

Epoxy resins, exemplified by bisphenol A diglycidyl ether, are widely used in coatings, electronic packaging, and composite materials. However, the conventional NaOH-based synthesis lacks precision, as the harsh alkaline conditions inevitably induce side reactions such as oligomerization and hydrolysis, thereby compromising resin quality. Here, we report an organocatalytic epoxide apparent exchange reaction that enables the precise synthesis of bisphenol A diglycidyl ether from bisphenol A and epichlorohydrin, in which the β-chlorohydrin groups in the ether intermediates undergo apparent exchange with the epoxide groups in epichlorohydrin. Computational studies revealed that the alkoxide in situ generated from epichlorohydrin ring-opening facilitates a hydrogen-bonding-mediated proton-transfer pathway that induces the dehydrochlorination of the β-chlorohydrin groups, thereby forming the target epoxide groups. This approach provides broad applicability to the synthesis of most commercial epoxy resins. Furthermore, this mild method overcomes the structural limitations of the NaOH process, providing an alternative route to polyester-based epoxy resins and promoting the development of sustainable epoxy materials.