Fabrication of eco-friendly durable superhydrophobic bamboo surfaces via HDTMS-modified silica nanoparticles

Bamboo is emerging as a renewable alternative to plastic and wood, with growing adoption in sustainable construction and consumer applications. However, its broader use is hindered by high water absorption and limited environmental durability, particularly in outdoor or high-humidity conditions. In this study, we aim to develop a facile and environmentally friendly method to endow bamboo surfaces with superhydrophobic and self-cleaning properties. To achieve this, a sol-gel composed of tetraethyl orthosilicate (TEOS) and hexadecyltrimethoxysilane (HDTMS) was uniformly applied to polished bamboo surfaces using a brush. This treatment promotes the formation of a dual-scale hierarchical surface, with hydrophobically modified SiO₂ nanoparticles aggregating into nano/micro clusters that provide excellent water repellency. The treated bamboo surfaces exhibited outstanding superhydrophobic performance, with a static water contact angle of 159° ± 2° and a sliding angle of just 8° ± 0.5°, enabling efficient water droplet roll-off. The coated surface also exhibited excellent mechanical durability, maintaining a water contact angle above 150° and complete dryness after 50 abrasion cycles under a 50 g load and 35 cycles under a 100 g load, demonstrating robust adhesion and sustained long-term water repellency. In addition, the coating showed excellent chemical stability, retaining consistent hydrophobic behavior across a wide pH range (3-13). The treated bamboo also effectively repelled common contaminants, including mud, sauces, and beverages, thereby reducing surface fouling and maintenance requirements. Overall, the superhydrophobically engineered bamboo represents a sustainable and multifunctional material platform with broad applicability in construction, outdoor furniture, and eco-friendly consumer products.