A synergistic metal ion–silane strategy enables fire-safe, water-repellent, and mold-resistant flattened bamboo board

Bamboo surface is engineered with a synergistic modification of metal ions–silane. • Coordinated alginate network provides flame retardancy and mold resistance. • Silane layer confers hydrophobicity and self-cleaning properties. • Crosslinked structure imparts excellent mechanical robustness. Flattened bamboo board (FB) characterized by its high raw-material utilization, large dimensions, and appealing aesthetics, holds potential for indoor furniture applications. However, its inherent hygroscopicity and flammability severely restrict its performance in humid or fire-sensitive environments. Herein, a multifunctional nanostructured coating system integrating metal-ion coordination and silane modification was developed to enhance the durability of FB. Specifically, Ca 2+ /Zn 2+ ions were first coordinated with sodium alginate to construct a bio-based alginate salt (AS) coating, followed by silane modification (PSO) to form an integrated AS/Ca-Zn@PSO coating, where the metal ion–silane synergy enabled concurrent improvements in flame retardancy, mold resistance, water repellency, and interfacial durability. The resultant FB functionalized with AS/Ca-Zn@PSO exhibited high flame retardancy (LOI = 32.3) with superior anti-mold performance, reaching the highest grade of level 0. Compared with untreated FB, the peak heat release rate and total smoke production of AS/Ca-Zn@PSO FB were reduced by 56% and 55%, respectively. Furthermore, the modified FB also maintained high hydrophobicity and flame retardancy after mechanical abrasion. This environmentally benign modification approach enables an effective route to valorize renewable bamboo into a sustainable material with favorable water resistance, anti-mold performance, and flame retardancy for indoor furniture applications. Download: Download high-res image (101KB) Download: Download full-size image