Facile preparation of mechanically durable, self-healing and multifunctional superhydrophobic surfaces on solid wood

Maintaining the hierarchically roughened structures and non-wetting properties are critically essential for a superhydrophobic surface upon sunlight irradiation, physical rubbing or organic contamination in practical applications but remain extremely challenging. Herein, by simply spraying a waterborne perfluoroalkyl methacrylic copolymer (PMC) emulsion mixed with TiO2 nanoparticles onto polydimethylsiloxane (PDMS) pre-coated substrates, mechanically durable, self-healing superhydrophobic surfaces were fabricated on solid wood. The coated surfaces exhibited exceptional repellency toward water as well as organic liquids with low surface tensions including ethylene glycol. The as-prepared coatings on the rigid wood substrate showed excellent durability against mechanical abrasion while retaining the rough surface textures due to the hydrophobic binder PMC anchoring the nanoparticles tightly on the surface, thus sustaining the superhydrophobicity of the surface. Moreover, the non-wetting properties of the surface damaged by ultraviolet (UV) irradiation can be automatically restored by a simple heat treatment, which facilitates the migration of the underlying hydrophobic PDMS onto the surface replenishing the necessary low-surface-energy materials. Besides, the TiO2-containing coatings exhibited photocatalytic activity in degrading organic contaminants and can also preserve the underlying wood substrate from photodegradation during UV exposure. The developed method herein features environment-friendly raw materials, facile processing and large-scale fabrication. Such superhydrophobic wood surfaces with multi-functionalities may open new avenues in the field of novel wood-based materials.