Studies on Analysis of Relationship between Permeation Separation and Membrane Structure for Organic Liquid Mixtures through Polymer Membranes

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Characteristics of permeation and separation for benzene/cyclohexane mixtures in pervaporation through polymer membranes were studied from the viewpoint of chemical and physical structure of the membranes, and mechanism of permeation and separation is also discussed.Liquid crystalline polymer membranes from poly(dimethyl siloxane)(PDMS) with mesogen group and methylmethacrylate-methacrylic acid copolymer membranes cross-linked with metal ions showed benzene-permselectivity. This permselectivity is significantly related to the chemical and physical structure of the membranes. Because depression of swelling of the membrane due to feed mixtures is remarkably improved permselectivity, chitosan and cellulose were benzoylated. These benzoylated chitosan and cellulose membranes were very high benzene-permselective. It made that hydrophilic-hydrophobic balance of the membrane was very important clear.Effect of factor of the membrane structure on the permselectivity for aqueous alcohol solutions was investigated from the viewpoints of chemical modification of hydrophilic polymers and construction of physical structure of the membrane. Optimum in degrees of hydrophilicity and cross-link of quaternized chitosan membranes gave high water-permselective. Poly [1-(trimethylsilyl)-1-propyne] membranes surface-modified with a PDMS-g-poly(fluoroacrylate) showed high ethanol-permselectivity for aqueous ethanol solutions.Graft copolymer membranes prepared from DMS macromonomer and alkylmethacrylates showed high volatile organic compound(VOC)-permselectivity for an aqueous dilute VOS solution. This permselectivity was significantly influenced by composition of graft copolymer, and furthermore was deeply related to morphology in microphase separated structure of the graft copolymer membranes.