Fabrication of super-hydrophobic and super-oleophilic boehmite membranes from anodic alumina oxide film via a two-phase thermal approach

The present work demonstrates a simple two-phase thermal method to prepare oriented boehmite [AlO(OH)] membranes directly from anodic alumina oxide (AAO) substrate with a copper catalyst. The acidity of the aqueous phase and reaction time play important roles in the formation of the oriented AlO(OH) membranes. Closely packed AlO(OH) crystals are parallel-aligned and vertically oriented on the substrates. The wetting properties of as-prepared oriented AlO(OH) membranes were first investigated by measuring the contact angles of water and oil on the surfaces. The oriented AlO(OH) membranes (without any modification by low-surface energy polymer) show both super-hydrophobicity, with a water CA as high as 152.8°, and super-oleophilicity with a heptane CA reaching to 0° within 0.25 s.