A cost-effective, high-efficiency, and environmentally friendly laccase-catalyzed catechol/polyethyleneimine-modified bamboo fiber/poly(butylene succinate-co-butylene adipate) composite.

Bamboo fiber-reinforced biodegradable composites have been increasingly regarded for their renewable origin, cost-effectiveness, and high specific strength. However, the inherent hydrophilicity of bamboo fibers (BFs) results in poor interfacial compatibility with poly(butylene succinate-co-butylene adipate) (PBSA), thereby limiting composite performance. Inspired by the adhesive mechanism of dopamine self-polymerization, a straightforward, cost-effective approach was proposed in this study, in which the BFs were modified through a laccase-catalyzed oxidation process employing polyethyleneimine-catechol (PEI/CAT) crosslinked networks. BFs were modified with PEI/CAT at six different concentrations (0, 0.25, 0.5, 1, 2, and 4 wt%) to identify the optimal treatment. The enzymatic system facilitates the grafting of a hydrophobic layer onto the BFs, enhancing fiber-matrix compatibility. Results demonstrate that a 2 wt% PEI/CAT treatment yields a uniform, optimal coating, markedly enhancing fiber surface roughness and interfacial adhesion. The modified BFs were then compounded with PBSA to fabricate composites with a mass ratio of 35 % fibers to 65 % matrix. Compared to the composite with unmodified BFs (0 wt%), the PEI/CAT-modified BFs-PBSA composite exhibits improved mechanical properties, with tensile, flexural, and impact strengths increased by 44.78 %, 44.74 %, and 34.26 %, respectively. The temperature at 5 % mass loss is elevated by 23.9 °C, the crystallinity of the composite reached a maximum of 61.5 %, showing a slight increase compared to the unmodified group. This study provides an environmentally friendly and efficient modification approach to develop high-performance biodegradable fiber composites.