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Polymeric gas separation membranes frequently undergo the phenomenon of aging, that is, performance parameters like permeability decrease with storage or usage time. Here, we report on a new approach of reducing aging by incorporation of functionalized multiwalled carbon nanotubes into a polymer of intrinsic microporosity. Free volume and permeability measurements clearly show a reduced aging with incorporation of the carbon nantubes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 213–217

Membrane-based separations are a promising attempt for desulfurization of fuels in petrochemical industry. The focus on research is to investigate membranes, which are more efficient and show better separation characteristics. Hybrid membranes made of an organic polymer and inorganic compounds combine both in one material and new properties can be realized. Here new hybrid membranes of polyimides and POSS (polyhedral oligomeric silsesquioxane) compounds for desulfurization by the membrane-based separation process pervaporation were investigated. The POSS compounds can act as cross-linking agent between polymer chains through reactive organic side groups, resulting in improved membrane properties. In pervaporation experiments the behavior of glycidyl-POSS hybrid membranes with different amount of POSS as additives have been analyzed for a binary mixture consisting of benzothiophene and n -dodecane in comparison to a native copolyimide membrane. Thereby the concentration of benzothiophene has been varied. The hybrid membranes showed lower fluxes due to cross-linking, correlating with PALS and WAXD results. At higher temperatures also higher selectivity is found. Furthermore in stress strain measurements the glycidyl-POSS hybrid membranes showed improved properties in comparison to a native membrane.

High free-volume copolymers were prepared via polycondensation with 2,3,5,6,-tetrafluoroterephthalonitrile (TFTPN) in which a portion of the 3,3,3\',3\'-tetramethyl-1,1\'-spirobisindane (TTSBI) of PIM-1 was replaced with dibutyl anthracene maleimide (4bIII). An investigation of free volume using positron annihilation lifetime spectroscopy (PALS), and gas permeation measurements was carried out for the thin film composite copolymer membranes and compared to PIM-1. The average free volume hole size and the gas permeance of the copolymer membranes increased with decreasing TTSBI content in the copolymer.