Biodegradable (A) x B n Alternating Copolyester: Achieving PET-like Performance with Enhanced Marine Degradation

The development of high-performance biodegradable polymers that simultaneously achieve petrochemical-plastic-like mechanical properties and controlled environmental degradability remains an unsolved challenge in sustainable materials science. We present an (A)xBn alternating copolyester platform engineered through a precision cascade polycondensation-ring-opening polymerization (PROP) strategy, featuring (i) ultrashort succinic acid (SA) soft segments (B), (ii) architecturally tuned hard-segment ((A)x) lengths, and (iii) spherulite-size-modulated semicrystalline morphology. This triple-design strategy yields unprecedented property combinations: 61 MPa yield strength and 428% elongation at break, matching PET’s elastic-plastic behavior (<300% strain) while exhibiting superior marine degradability (60% mass loss in 90 days across lake/seawater). The material further enables closed-loop chemical recycling to high-purity glycolic acid, establishing a new paradigm for circular polymer design that addresses both microplastic generation and end-of-life management challenges.