Fabrication of Superhydrophobic–Superoleophilic Fabrics by an Etching and Dip-Coating Two-Step Method for Oil–Water Separation

A dual-scale roughness
structure superhydrophobic–superoleophilic
fabric was fabricated by first etching the microscale fibers with
alkali and then dip-coating in a mixed solution of a polymer of intrinsic
microporosity (PIM-1) and fluorinated alkylsilane (PTES). Scanning
electron microscopy analysis showed that the etching process created
nanoscale pits on the fiber surface and subsequently formed hierarchical
structures on the fabric surface. Coating of PIM-1–PTES on
the etched fibers significantly lowered the surface energy of the
fibers, thus causing the fabric surface to possess superhydrophobicity
with a water contact angle of 158° and superoleophilicity with
an oil contact angle of 0°. The obtained superwettable fabric
was mounted in a leak-proof manner on the open-end glass bottle, like
an oil skimmer container. Such a new surface-tension-driven, gravity-assisted,
one-step, oil–water separation device was used to separate
the oil–water mixture with a separation efficiency as high
as 99.96% after 30 recycles.