Utilization of membranes offers the promise of extraordinary energy savings if successfully applied to hydrocarbon-hydrocarbon and other organic separations. A common difficulty in utilizing membranes to separate organic liquids is that many common polymeric materials cannot withstand long-term exposure to organic liquids at the moderately high temperatures that are desirable. The approach taken in the present project is to use physical blends of rubbery and glassy materials that are chemically crosslinked. Blending allows for control of the solubility selectivity of the membrane while chemical crosslinking provides sufficient robustness to meet technical requirements. Utilizing group contribution concepts from polymer solution thermodynamics it is shown how blended materials can be formulated, in an a priori manner, for specific membrane separations. These concepts are demonstrated on the system of benzene-cyclohexane for which the resulting blend exhibits record performance, having both excellent selectivity and very high flux.
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