Anisotropic membrane

A membrane in which the pore openings are larger on one side than the other. The membrane must be oriented correctly to obtain the best filtration characteristics.

A typical anisotropic membrane has a thin, dense surface layer that is supported on a more open, thicker porous structure. These membranes have the advantage of higher fluxes, and most commercial processes use such membranes.
Loeb-Sourirajan membrane, Interfacial (Thin-film) composite membrane, liquid membranes.