Polyrotaxane Architecture Enables Unprecedented Toughness and Marine Degradability in Sustainable Polyesters

Biodegradable polyesters are a promising solution for plastic pollution; however, their widespread adoption is hindered by their poor mechanical properties and lack of marine degradability. Conventional bulk property modifications cannot overcome this trade-off. Herein, the incorporation of polycaprolactone-grafted polyrotaxane, a mechanically interlocked supramolecular additive that modifies the polymer chain mobility and crystallization behavior, is demonstrated to simultaneously enhance the toughness and marine biodegradability of polyesters. Using poly(butylene succinate) as a model system, we demonstrate that the toughness increased by 300% without reducing the tensile strength and Young’s modulus. Remarkably, this molecular engineering approach creates a “multi-lock biopolymer” to enhance the marine biodegradation 4-fold, with UV exposure triggering accelerated degradation to 10-fold. This strategy provides a new pathway for the development of high-performance biodegradable plastics with tunable degradation profiles, thereby addressing both the mechanical and environmental challenges of sustainable polymers.