Preparation of wood super-hydrophobic coating using the sand-in method

Abstract

Owing to the absence of well-defined mechanical properties and the substantial cost and intricacy associated with the production process, the extensive-scale manufacturing and practical use of super-hydrophobic coatings face constraints. This study presents a cost-effective and straightforward method, known as the ‘sand-in’ method, for the large-scale preparation of super-hydrophobic coatings. Epoxy resin (EP) is used as the primer, whereas a blend of EP and polydimethylsiloxane (PDMS) acts as the topcoat. The sanding step between coatings is replaced by sandpaper rotating sanding silica (SiO2). A hierarchical structure comprising a ‘primer–sand–topcoat’ sequence was established, resulting in the formation of a continuous and dense three-dimensional network structure composed of EP, PDMS and SiO2 on the surface of the wood. This coating combines the robust mechanical strength of EP with the low surface energy of PDMS. The coating exhibits a contact angle of 163.2° and a roll-off angle of 2°. It further boasts exceptional mechanical durability, chemical stability, self-cleaning and anti-fouling properties. Notably, it retains its super-hydrophobic ability even after prolonged exposure to outdoor conditions for 30 days. This method offers an innovative approach for creating super-hydrophobic coatings on wood surfaces and holds promising applications across various industrial sectors.