Efficiently texturing hierarchical epoxy layer for smart superhydrophobic surfaces with excellent durability and exceptional stability exposed to fire

Coating superhydrophobic protective layers onto the lignocellulosic materials is promising to endow them with multifunctions, including waterproof, flame retardance, etc. However, appropriate approaches capable of engineering durable superhydrophobic lignocellulosic materials are still lacking. In this work, we developed an efficient thermally driven strategy to prepare durable superhydrophobic surfaces without the need for complicated pre/post treatment by immersing the lignocellulosic materials into a sealed vessel with a mixture of massive epoxy and SiO2 nanoparticles (NPs). The hierarchical structure was induced by the epoxy layer with micrometer-sized pores and the incompletely enclosure of SiO2 NPs. The unique hierarchical structure contributes to the superhydrophobic surfaces with a remarkable contact angle of 156 degrees and sliding angle of 2 degrees. Such prepared water repellent surfaces exhibited excellent durability when are subjected to mechanical abrasion, chemical corrosion, and harsh environmental conditions. In particular, the functional surfaces retained their original superhydrophobicity even when directly exposed to fire for 50 s. These surfaces fabricated on lignocellulose-based materials displayed exceptional flame retardancy manifested by a significant improvement in ignition delay. The superhydrophobic surfaces with impressive mechanical stability, superior thermal stability, and flame retardancy hold substantial potentials for practical applications in a broad range of fields.