The separation of gases and liquids using membranes is obviously critically related to the solubility and diffusivity properties of materials in polymeric membranes. The Center not only has the capability to measure these various important physical properties, but is unique in correlating and predicting the interaction of two or more permeants in a polymer membrane which is particularly important in some membrane processes as perevaporation. It should be noted that the Center has not developed the expertise to synthesize new membrane materials, but has concentrated on the characterization of materials supplied to the Center.