Chemically Recyclable Alternating Poly(thioether<i>‐alt</i>‐ester)s with Tunable Properties Enabled by Substitution Effects and Stereochemistry

Abstract The development of innovative poly(ether‐ester)s with perfectly alternating ether and ester functionalities to overcome the trade‐offs between the polymer's depolymerizability and performance properties is in high demand for advanced material applications and sustainable development. Herein, we prepared a series of enantiopure cyclic thioether‐ester monomers bearing various pendant substituents by a facile “polycondensation‐depolymerization” strategy. The controlled ring‐opening polymerizations of these enantiopure monomers will afford stereoregular poly(thioether‐ alt ‐ester)s with structural diversity. The varieties of substituent size, position and stereo‐configuration provide the opportunity to systematically investigate polymerization kinetics and thermodynamics as well as structure‐properties relationship for the resulting poly(thioether ‐alt ‐ester)s. The strategic positioning of α‐, γ‐, and δ‐substituents coupled with stereoregular chain architectures and stereocomplex formation enables wide‐range modulation of the polymer's thermal and mechanical properties. A(hard)‐B(soft)‐A(hard) triblock thermoplastic elastomers with good mechanical performance and elastic recovery were also created by sequential polymerization. Of note, these polymers can be chemically recycled by either ring‐closing depolymerization or alcoholysis, with high monomer regeneration efficiency. The systematic investigation of substitution effects and structure‐property relationships in this work provides a molecular blueprint for designing novel chemically recyclable polymers with high performance.