(462d) Membrane Separations with High Selectivity

We have recently discovered that a particular variety of a type of perfluoropolymer membrane, perfluoro-2, 2-dimethyl-1, 3-dioxole copolymerized with tetrafluoroethylene, (PDD-TFE), has extraordinary selectivity in separating organic solvent mixtures by reverse osmosis. For example, from a mixture of an aromatic solvent, toluene, with a variety of polar aprotic solvents such as NMP, DMSO, DMF, pure toluene can be obtained as permeate. We have been making preliminary explorations of a variety of systems using such a glassy copolymer with a very high fractional free volume. The types of systems studied include aromatic-polar aprotic, polar protic - polar aprotic, aromatic - polar protic1/2 among others. We will describe our results for these and other types of systems and seek potential explanations for such behavior.