Development of new ionomer blend membranes, their characterization, and their application in the perstractive separation of alkenes from alkene-alkane mixtures. I. Polymer modification, ionomer blend membrane preparation, and characterization

In this contribution, the synthesis and characterization of novel ion-exchange blend membranes which contain the SO3Ag group for the application in the perstractive separation of alkene–alkane mixtures, where the Ag+ ion serves as facilitated transport site for the alkene via formation of a pi complex with the alkene double bond, is presented. In this part of the article, the synthesis and characterization of following blend membrane types are described: (1) acid–base blend membranes of ortho-sulfone-sulfonated polysulfone (PSU) with ortho-sulfone-diaminated PSU; (2) blend membranes of ortho-sulfone-sulfonated PSU with unmodified PSU; (3) blend membranes of ortho-sulfone-sulfonated PSU with ortho-sulfone disilylated PSU. The differently modified PSU types were characterized via 1H nuclear magnetic resonance (1H-NMR). The acid–base blend membranes were characterized via Fourier transfer infrared (FTIR) spectroscopy. It could be indirectly proved that formation of PSU–SO3+H3N–PSU ionic crosslinks takes place. Transmission electron microscopy (TEM) investigations of (1) and (2) yielded the results that these blends are inhomogeneous at the microscopic scale. Mechanical stabilization of these blends is accomplished by physical entanglement of the different macromolecules. The blends (3) were macroscopically inhomogeneous due to the strong difference in hydrophilicity of the blend components. Only the blend 90% PSU–SO3H10% PSU[Si(CH3)3]2 formed a blended membrane.