Achieving durable superhydrophobicity on wood tangential surfaces through alkali–etching–induced roughness

Wood surface superhydrophobic modification effectively mitigates liquid–water–induced shrinkage/swelling, enhancing dimensional stability. However, most researches focus on wood transverse sections due to inherent roughness, whereas few have achieved superhydrophobicity on environmentally exposed tangential surfaces. Furthermore, practical application of superhydrophobic wood remains challenging due to its poor interfacial stability. Herein, a scalable alkali etching strategy that partially removes hemicellulose/lignin to enhance roughness and active sites on wood tangential surfaces is proposed. Subsequent spraying of hydroxyapatite-polydimethylsiloxane (HAP-PDMS) composite solution forms a robust superhydrophobic coating. Etching-induced microcracks and voids facilitate nanoparticle anchoring, synergistically functioning with the cellular framework as a protective barrier to ensure exceptional durability. The modified surface can withstand mechanical abrasion, chemical corrosion, and UV exposure, retaining superhydrophobicity after 60-day outdoor aging. Notably, it exhibits autonomous self-healing: post seven abrasion-repair cycles, the water contact angle recovers to 142° (92.4% restoration efficiency). This work provides an economical route to engineer stable superhydrophobic tangential wood surfaces, extending product service life. Graphical abstract