Recyclable Thermoplastic Poly(urethane-urea)s with Enhanced Mechanical and Adhesive Properties Derived from CO₂-Based...

Polyurethanes (PUs) with high-performance and recyclability remain challenging due to their complex structures and limited depolymerization pathways. Herein, we report a sustainable thermoplastic poly(urethane-urea) system based on renewable ε-caprolactone (CL)/3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP) copolyester diols derived from CO₂ and 1,3-butadiene. By regulating EVP incorporation (0-19 mol %), the polymer microstructures and mechanical properties are systematically tuned. EVP units disrupt poly(ε-caprolactone) (PCL) crystallization and reduce the spherulite size, leading to enhanced toughness and elastomeric behavior. An optimal performance is achieved at 11 mol % EVP, where PU₁₁ exhibits a tensile strength of 33 MPa and an elongation at break of 1079%, outperforming commercial SBS/SEBS elastomers. On the other hand, PU₆ with an intermediate 6 mol % EVP achieves excellent adhesive performances to metal plates, showing a lap shear strength of 4.76 MPa. Moreover, the polyester segments in these poly(urethane-urea)s undergo efficient chemical recycling via mild thermolysis conditions (170 °C, Sn(Oct)₂), enabling the recovery of pure EVP and CL monomers with a total yield of 94%. This work demonstrates a rational molecular design strategy that integrates mechanical performance with recyclability, providing a viable pathway for sustainable high-performance PU-based materials.