Abstract: Hydrophobic, asymmetric membranes are formed integrally from elastomeric polymers. The membranes have a dense, discriminating layer and a thick, porous support layer and require no other support. The membranes of the invention provide an economic advantage over prior art composite membranes used for separating target organics from a mixture. Using the methods of the invention it is possible to separate two or more organic components wherein discrimination is made on the basis of molecular size.

Abstract: Hydrophobic, asymmetric membranes are formed integrally from elastomeric polymers. The membranes have a dense, discriminating layer and a thick, porous support layer and require not other support. The membranes of the invention provide an economic advantage over prior art composite membranes used for separating target organics from a mixture.

Abstract: Using the methods of the invention, an elastomeric polymer is dissolved in a suitable solvent, cast in one of the membrane casting techniques using a phase inversion technique, and immersed in a coagulation bath comprised of suitable solvent/non-solvent pairs (e.g., THF/water and ethanol). Asymmetric membranes having a dense discriminating layer and a thicker porous support layer suitable for application in pervaporation processes were obtained in a single step. An increase of the polymer concentration in the casting solution gives a more dense layer. When cast as formed using the methods of the invention, the membrane obtained is an integrally skinned membrane comprising a thin, dense separation layer over a porous support layer (asymmetric membrane) formed in a single casting operation. The resulting membrane is homogenous with respect to chemical composition.

Abstract: Hydrophobic, asymmetric membranes are formed integrally from elastomeric polymers. The membranes have a dense, discriminating layer and a thick, porous support layer and require not other support. The membranes of the invention provide an economic advantage over prior art composite membranes used for separating target organics from a mixture.

Abstract: The present disclosure is directed to composite membranes formed by casting thin (about 8 to about 20 microns) film of perfluorosulfonic acid (PFSA) polymer on a porous matrix of polytetrafluoroethylene (PTFE). The ion exchange groups in these membranes are protons and can be substituted with metal ions such as Na.sup.+, Ca.sup.+, Ag.sup.+, etc. or by organic ligands. Alternatively, even thinner membranes (from about 1 micrometer or thinner up to 20 micrometers) can be formed by spraying a PPSA polymer solution on a porous matrix. The porous matrix may comprise polytetrafluoroethylene alone or in combination with a thermobonded polypropylene support.Both the acid and the substituted membranes have remarkable affinity for polar compounds or mixtures of polar and non-polar compounds such that azeotropic mixtures of organic compounds as well as close-boiling liquid mixtures can be easily separated at good permeation rates using the technique of pervaporation.