Derived from a strategically chosen hexafluorinated dicarboxylate linker aimed at the designed synthesis of a superhydrophobic metal-organic framework (MOF), the fluorine-rich nanospace of a water-stable MOF (UHMOF-100) exhibits excellent water-repellent features. It registered the highest water contact angle (≈176°) in the MOF domain, marking the first example of an ultrahydrophobic MOF. Various experimental and theoretical studies reinforce its distinctive water-repellent characteristics, and the conjugation of superoleophilicity and unparalleled hydrophobicity of a MOF material has been coherently exploited to achieve real-time oil/water separation in recyclable membrane form, with significant absorption capacity performance. This is also the first report of an oil/water separating fluorinated ultrahydrophobic MOF-based membrane material, with potential promise for tackling marine oil spillages.

A facile one-step dip-coating method is reported here to prepare recyclable superhydrophobic polypropylene membrane. The membranes with nanoscale surface roughness and contact angle (water) greater than 150° were created by dipping polypropylene fabric film in solution of silica nanoparticles networked with alkylsiloxanes and they exhibited excellent oil flux for oil-water separation under gravity-induced simple separation system. Taking into consideration of its separation selectivity, productivity flux, reusability and endurance, the membrane shows promising in treatment of oily wastewater and oil spill cleanup.

Poly(dimethylsiloxane) (PDMS) membrane, which is generally prepared by cross-linking a hydroxylterminated-poly(dimethylsiloxane) liquid with a polymethylhydrosiloxane cross-linker through a condensation reaction between the hydroxyl end groups and hydride groups liberating hydrogen, is one of the most studied polymeric membranes for the separation of gases and liquids. Herein, a new PDMS membrane series prepared by direct cross-linking hydroxyl terminated polydimethylsiloxane pre-polymer liquid with RSiCl 3 molecules of different types in n-heptane solvent under a nitrogen environment were studied, wherein the alkyl chain, R, was varied as methyl CH 3 , octyl C 8 H 17 , perfluorooctyl C 8 H 4 F 13 , and octadecyl C 18 H 37 . For each membrane series, the amount of cross-linker to pre-polymer was varied as 13 : 87, 33 : 67 and 50 : 50 (w/w) to compare the membranes at different cross-linking densities. The cross-linked network structure of the membrane comprised dimethylsiloxane network structures of two cross-links and alkylsiloxane network structure of two or three cross-links. The changes in the structure and properties of the membranes depending on the concentration and type of trichloro(alkyl)silane used were observed by XRD, SEM, TEM, SANS, TGA, DSC, 29 Si NMR, IR, cross-linking density, contact angle (water) and ethanol-water separation performance measurements. The membranes with an optimal amount of trichloro(alkyl)silane cross-linker of approximately 10-30% (w/w) showed better separation performance than the other reported conventional PDMS membranes in terms of the ethanol selectivity and flux from an aqueous feed containing 5% (w/w) ethanol. Among the membranes prepared, the membranes cross-linked with perfluorooctylsiloxane/octadecylsiloxane showed better separation performance than those membranes cross-linked with methylsiloxane/octylsiloxane. Scheme 1 Cross-linking reaction of PDMS with organosilanes.This journal is