Eugenol-based polyester and its bamboo fiber composite with enhanced mechanical and anti-ultraviolet properties

Eugenol (UG) is a sustainable allyl-substituted guaiacol that easily becomes the monomer for acyclic diene metathesis (ADMET) polymerization. Nevertheless, ADMET polymers usually have a moderate molecular weight and poor mechanical properties, which cannot meet the demand of daily use. Herein, UG is used as the starting material for polymerization and modification of polymers, aiming at improving the mechanical properties of UG-based polymers and realizing their functional application. A class of biobased unsaturated polyesters was prepared by ADMET polymerization of α,ω-dienes derived from UG bearing an allyl group, and the UG-based polyesters showed improved intrinsic anti-ultraviolet (UV) performance with a UV protection factor (UPF) ranging from 10.9 to 48.2 compared with furan-based ADMET polyesters. Meanwhile, UG was used as a comonomer to undergo inverse vulcanization with elemental sulfur, affording a novel polysulfide as the crosslinking agent. By adding raw bamboo fiber, the obtained polymer composite with enhanced mechanical properties and reprocessability exhibited excellent anti-UV performance with a superior UPF of 252 and could almost maintain its original mechanical properties and UV protection ability even after prolonged exposure to UV light. This work provided an effective approach for preparing renewable functional polyesters and plant fiber-toughening polymer composites with an expanded application field.