Research on membrane-based separation technology is growing rapidly in the U.S. and in the other industrialized nations. While significant advances in polymeric materials have been made recently, there is still a gap in application of polymers in industrial processes, and there is much that needs to be done in designing polymer blends for membranes for use in separation tehcnology. There have been very few research efforts in this critical area, and this proposal offers a much-needed initiative. Specifically, this proposal outlines some preliminary work designed to investigate systematically the relation between the physical and chemical properties of polymeric membranes and their permeability and separation efficiency of those membranes.