Laccase-catalyzed octadecylamine modification enables green and stable hydrophobization of bamboo

Abstract

Bamboo has attracted widespread attention owing to its strong mechanical properties, availability in numerous regions, and green and low-carbon nature. However, the hydrophilic nature and susceptibility to mold growth limit its wide application. Therefore, this study uses green biological enzyme technology to improve the hydrophobic performance of bamboo, grafting hydrophobic monomer octadecylamine (OA) onto bamboo surfaces under the catalysis of laccase. The optimum reaction conditions such as the amounts of OA monomer and laccase, reaction time, and temperature were determined. Under these optimized conditions, the contact angle of treated bamboo reached 121°± 3°, which was six times higher than that of untreated bamboo, and its hydrophobicity is very stable compared to that of OA-bamboo, could withstand soaking and washing with hot water, ethanol and acetone, and the change rate of contact angle during 180s test was ∼1%. Moreover, as the water absorption rate of bamboo decreased, the defects of bamboo susceptible to mildew growth also considerably improved. The hydrophobic modification mechanism was studied using SEM (scanning electron microscopy), ¹H-NMR (nuclear magnetic resonance), and XPS (X-ray photoelectron spectroscopy), this analysis confirmed that OA grafting onto bamboo under laccase catalysis resulted in stable hydrophobicity. Moreover, OA chemically reacted with lignin in bamboo, possibly forming a C–N bond. This study provides valuable insights into the expanding applications of bamboo as sustainable materials.