Robust Superhydrophobic Composite Featuring Three-Dimensional Porous Metal Rubber with an Embedded Carbon Nanofiber Network for Emulsion Separation

Superwetting materials for emulsion separation have attracted considerable attention in recent years as a way to combat increasing environmental pollution. However, there are still major challenges regarding the durability of superwetting materials and separating emulsions with high viscosities and/or complex compositions. Metal rubber (MR) with a robust three-dimensional (3D) porous structure has received significant attention for solving such challenges. In this study, carbon nanofiber-reinforced polydimethylsiloxane (CNF-PDMS) is subtly deposited into MR pores via a vacuum filtration method to form an extremely superhydrophobic and superoleophilic MR/CNF-PDMS composite with a unique embedded network structure. This material can efficiently separate water-in-oil (gasoline, diesel, engine oil, and lubricating oil) emulsions with high viscosities and complex compositions from mechanical systems. Additionally, the corrosion resistance of MR is significantly improved through embedding CNF-PDMS particles, and the MR/CNF-PDMS composite remains superhydrophobic after being soaked in acid, alkali, and salt solutions for 15 days. Most importantly, the excellent mechanical properties of MR can support the CNF network structure of the CNF-PDMS such that the MR/CNF-PDMS composite can withstand high impact and wear forces. In particular, discretely or partially superhydrophobic MR/CNF-PDMS obtained after wear treatment can still perform efficient emulsion separation. This work provides a basis for fabricating extremely robust superhydrophobic materials with unique structures for emulsion separation, showing considerable potential for large-scale practical applications.