Bioinspired superhydrophilic/underwater superoleophobic surfaces with robust wax-prevention, self-cleaning, and oil/water separation functions

Abstract

Recently, much attention has been paid to underwater superoleophobic surfaces for their great potential in the industry. However, the large-scale practical utilization of the current underwater superoleophobic coatings is mainly limited by their complex and expensive fabrication processes and poor physical and chemical durability. Consequently, we fabricated a bioinspired superhydrophilic and underwater superoleophobic poly(vinyl alcohol)/montmorillonite composite surface by a facile, green process. This composite surface demonstrated excellent anti-wax and self-cleaning properties. The outstanding mechanical and chemical stabilities of this surface allowed it to retain its underwater superoleophobicity after 50 cycles of sandpaper abrading or prolonged immersion in corrosive solutions. Additionally, stainless steel mesh coated with this composite surface could separate various oil/water mixtures, including emulsions, driven only by gravity with an ultrahigh separation efficiency (>99.2%). Furthermore, the coated mesh achieved an extremely high separation efficiency of 98.6% and a separation flux of 37 098.6 L m⁻² h⁻¹ following 30 separation cycles. This multifunctional composite surface holds tremendous promise for large-scale practical applications.