Anisotropic hydrophobic/hydrophilic nanoporous membranes and methods of forming anisotropic hydrophobic/hydrophilic nanoporous membranes are disclosed. The method of forming the nanoporous membrane includes growing a nanoporous oxide film on a substrate. A nanoporous membrane having a top side and a bottom side can then be formed by partially separating the nanoporous oxide film from the substrate. A fluorocarbon film can be deposited on the top side of the nanoporous membrane by plasma polymerization. The disclosed anisotropic hydrophobic/hydrophilic nanoporous membranes can have extremely different hydrophobicity between the top side and the bottom side of the nanoporous membrane.