Lithium‐Salt‐Driven Lewis Pair Polymerization for Chemically Recyclable and Ion‐Conductive Polyester Elastomers

ABSTRACT

Herein, we report a lithium‐salt‐driven Lewis pair polymerization (LPP) strategy to accomplish controlled polyester synthesis, ionic conductivity, and closed‐loop recyclability within a single platform. The combination of commercial lithium salts (LiTFSI or LiCF ₃ SO ₃ ) and a novel bifunctional N ‐heterocyclic olefin (NHO) enables rapid and living ring‐opening polymerization of diverse lactones ( ε ‐caprolactone, δ ‐valerolactone, and rac ‐lactide) under mild conditions, affording well‐defined block copolymers with predictable molecular weights and narrow molecular weight distributions. Kinetic and mechanistic studies reveal a nonclassical zero‐order dependence on the concentrations of both monomer and Lewis acid, governed by the multi‐coordination capability of lithium cations. Distinct from traditional polymerizations, the residual lithium salts are retained in situ to impart competitive ionic conductivity, which enables the fabrication of ion‐conductive polyester elastomers with highly tunable mechanical properties ( ε ∼229%‒2111% and σ ∼1.6‒37.4 MPa) and room‐temperature ionic conductivities (up to 10 ⁻⁵ S/cm) through a one‐step protocol. A comprehensive evaluation of the strain sensitivity, electrical hysteresis, response/recovery behavior, and cyclic sensing performance supports their potential for applications in reliable, real‐time flexible strain sensing. Furthermore, both the polyester matrix and lithium salts can be efficiently recovered, realizing full closed‐loop recycling. This catalyst‐to‐function paradigm provides a general blueprint for integrating catalysis, functionality, and circularity in polymer design.