Dynamic Cross-Linked Poly(butylene adipate-<i>co</i>-terephthalate) Networks via Functional Eugenol for Simultaneous Enhancement of Mechanical, Processing, and Photothermal Performance

Poly(butylene adipate-co-terephthalate) (PBAT) films with high flexibility are highly suitable as a biodegradable alternative to low-density polyethylene (LDPE) films, which can significantly reduce the environmental accumulation of mulch films. However, improving the mechanical strength and processability of PBAT, and developing its photothermal function, remain challenging. Herein, we present dynamic cross-linked PBAT networks via multifunctional eugenol (DPE) to simultaneously enhance the mechanical, processing, and photothermal properties. The DPE samples exhibit a 49.1% increase in tensile strength, nearly 600% elongation at break, and a creep strain of only 1.3% at 130 °C, attributed to the increased intermolecular interactions and rigid aromatic units from the epoxidized eugenol cross-linker. Additionally, DPE samples demonstrate significant melt strain-hardening during extensional flow, due to the dynamic cross-link points slowing down chain dynamics and facilitating network strand stretching. Eugenol also imparts unique optical properties to DPE, such as UV resistance, photothermal conversion, and visible light transmittance. Under one sun intensity, the DPE films can heat to 68.5 °C and increase soil temperature by 7.2 °C compared to pure PBAT films. This innovative dynamic cross-linked PBAT network via eugenol not only enhances strength and processability but also enables efficient solar-to-thermal conversion, advancing the development of high-performance biodegradable photothermal mulching films.