Abstract: Novel copolymers that are fluoropolymers including a first repeat unit that is fluorinated and cyclic and a second repeat unit from a trifluorovinyl methylene ether monomer having sulfur or sulfone functionality in the pendant group are disclosed. The copolymers have relatively high gas permeability as a result of a cyclic repeat unit in the copolymer backbone and ionomers from oxidation of the sulfur containing functionality are particularity useful in the cathode structure of a proton exchange membrane fuel cell.

Abstract: This invention discloses a method for separation of an aromatic compound from a mixture comprising an alkane using an improved thin-film composite membrane. The membrane is particularly useful for separation of benzene from cyclohexane, which have similar boiling points. The membrane comprises a more mechanically durable and defect-free separation layer as a result of its fabrication from an ionomer solution that is substantially free of dissolved ionic species not associated with the ionomer.

Abstract: Separation of linear and branched alkane isomers via selective permeation through a composite membrane is disclosed. The separation layer in the composite membrane is fabricated from a blend of at least two different fluoropolymer compositions, A and B, in which composition A has a normal-alkane isomer permeability that is greater than composition B. Composition B has a normal alkane to branched-alkane isomer selectivity that is equal or greater than composition A. The separation layer in the composite membrane has a normal-alkane permeability that is greater than composition B and a normal-alkane to branched alkane isomer selectivity that is greater than composition A.

Abstract: This invention discloses an improved thin-film composite membrane and processes that use the membrane for the separation of gaseous mixtures that include an alkene. The membrane is particularly useful for separation of alkenes from alkanes or the separation of alkenes from other non-hydrocarbon gases. The membrane has a more mechanically durable and defect-free gas-separation layer that is fabricated from an ionomer solution that is substantially free of dissolved ionic species not associated with the ionomer and the mean helium permeability of the thin-film composite membrane is less than two times greater than the intrinsic helium permeability of the gas-separation layer.

Abstract: Membranes having a permselective active layer of a copolymerized perfluorinated monomer and an non-fluorinated alkylvinylester monomer demonstrate superior selective permeability performance for separating gas mixtures compared to membranes of exclusively perfluorinated polymers. Preferred active layer compositions are copolymers of perfluoro-2,2-dimethyl-1,3 dioxole (PDD) copolymerized with an alkylvinyl ester such as vinyl acetate, and vinyl pivalate, and with alkylvinyl esters that are substantially hydrolyzed to provide copolymerized vinyl alcohol functionality. The membranes can have a thin, high diffusion rate, “gutter layer” of a fluorinated polymer highly permeable to nitrogen positioned between the active layer and a porous support layer. A novel copolymer effective in selectively permeable membranes is a copolymer of PDD and an alkylvinyl ester compound having the formula H2C?CHOC(O)R1 in which R1 is a linear or branched alkyl group of from 2 to 5 carbon atoms.

Abstract: Composite membranes comprised of at least two layers, one of the layers being a silver ionomer and a second layer which is a fluorinated polymer with certain permeability properties, are especially useful for the separation of alkanes from alkenes, Particularly useful is a three-layer composite membrane in which a porous layer is laminated to the second layer.

Abstract: A metal exchanged fluorinated ionomer is a copolymer minimally including repeating units of (i) a polymerized derivative of a perfluorinated cyclic or cyclizable monomer and (ii) a strong acid highly fluorinated vinylether compound in which the acid moiety is exchanged with a cation of a Group 11 metal. Metal exchanged fluorinated ionomers are readily soluble and can be formed into thin, selectively gas permeable membranes by solution deposition methods. These membranes are suitable for separating olefins from gas olefin/paraffin mixtures. Good selectivity and transmembrane flux can be obtained without humidifying the membrane feed gas mixture.

Abstract: A highly fluorinated polymer is very useful as an acid catalyst. The highly fluorinated polymer has at least two repeating unit types that are the polymerized derivatives of a perfluorinated cyclic or cyclizable compound and a highly fluorinated vinyl ether compound having a sulfur containing functional group. The polymer can be formed by radical copolymerization of the fluorinated monomers with the sulfur-containing functional group in sulfonyl fluoride form (—SO2F) that is subsequently converted to sulfonic acid form (—SO3H). The highly fluorinated polymer can be used to advantage in a solution comprising an aprotic, polar organic solvent that has a dielectric constant of at least 15 and preferably is free of hydroxyl functional groups. Suitable solvents are those in which the polymer is soluble to at least 1 wt %. Hydroxyl group-containing protic, polar organic solvents are less preferred.

Abstract: A highly fluorinated polymer is very useful as an acid catalyst. The highly fluorinated polymer has at least two repeating unit types that are the polymerized derivatives of a perfluorinated cyclic or cyclizable compound and a highly fluorinated vinyl ether compound having a sulfur containing functional group. The polymer can be formed by radical copolymerization of the fluorinated monomers with the sulfur-containing functional group in sulfonyl fluoride form (—SO2F) that is subsequently converted to sulfonic acid form (—SO3H). The highly fluorinated polymer can be used to advantage in a solution comprising an aprotic, polar organic solvent that has a dielectric constant of at least 15 and preferably is free of hydroxyl functional groups. Suitable solvents are those in which the polymer is soluble to at least 1 wt %. Hydroxyl group-containing protic, polar organic solvents are less preferred.

Abstract: A portable breathing air supply apparatus uses a membrane separation module to obtain oxygen enriched air from ambient air which is blown into the module by an electrically powered fan. Oxygen enriched air is withdrawn from the permeate side of the membrane by a vacuum pump and is stored in a reservoir while the user exhales. In a preferred mode, a conserver valve in a tube leading from the reservoir to the user's mouth or nose is triggered to feed the enriched air for a preselected duration after a sensor in the tube detects onset of inhalation. Power for the electrical components can be supplied by batteries. The portable apparatus is sufficiently compact and light to be transported by persons weakened by certain chronic breathing disorders, such as chronic obstructive pulmonary disease and emphysema, and thus frees the user to roam for long periods away from a primary source of oxygen.

Abstract: A novel method of operating an internal combustion engine employs a selectively gas permeable membrane to provide either oxygen or nitrogen enriched air feed to beneficially affect engine performance. By feeding enriched air from a membrane unit such performance parameters as reduced NOx emissions, lean burn limit, engine power, and reduced cold start emissions can be enhanced relative to feeding ambient air. The selectively gas permeable membrane unit further includes a nonporous membrane (i) having an oxygen/nitrogen selectivity of at least 1.4 and a permeability to oxygen of at least 50 barrers; (ii) formed from an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole; and (iii) being at a temperature below the glass transition temperature of the amorphous copolymer.A cylindrical module having many substantially parallel aligned small diameter hollow fiber membrane structures is ideally suited for carrying out the novel method.

Abstract: A process for placing an ultra thin layer of a non-porous gas permeable polymer continuously over an entire filter surface area allows the fabrication of compact, high flux, fouling resistant gas filters. The process involves contacting a dilute coating solution of gas permeable polymer in a solvent with one side of a microporous substrate. The pore size of the substrate is chosen for its ability to effectively filter the gas permeable polymer from the coating solution. Solvent of the coating solution is made to flow through the microporous substrate which causes an ultra thin layer of polymer to build up on the side of substrate. When a desired thickness of polymer is built up, the solution and solvent is removed and residual solvent is evaporated, preferably by passing a gas at high rate over the surface of the polymer layer.This process can be used to coat flat sheet and hollow fiber substrates.

Abstract: A method of adding or removing a gas to or from a solution of the gas in a liquid involves transferring the gas between the liquid and another fluid through a membrane unit. The membrane unit includes a membrane which is (i) substantially impermeable to the solvent and having a permeability to oxygen of at least 100 barrers; (ii) formed from an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole; and (iii) is maintained at a temperature below the glass transition temperature of the copolymer. The fluid can be another liquid or a gas. The novel method provides very high rates of gas transmission between liquids and permits gasifying liquids without resort to sparging bubbles through the liquid. The method thus can gasify liquid with superior efficiency and without excessive agitation due to bubbling.

Abstract: A method of adding or removing a gas to or from a solution of the gas in a liquid involves transferring the gas between the liquid and another fluid through a membrane unit. The membrane unit includes a membrane which is (i) substantially impermeable to the solvent and having a permeability to oxygen of at least 100 barrers; (ii) formed from an amorphous copolymer of perfluoro-2,2-dimethyl-1,3-dioxole; and (iii) is maintained at a temperature below the glass transition temperature of the copolymer. The fluid can be another liquid or a gas. The novel method provides very high rates of gas transmission between liquids and permits gasifying liquids without resort to sparging bubbles through the liquid. The method thus can gasify liquid with superior efficiency and without excessive agitation due to bubbling.