Manshi Ohyanagi

Oxygen-permselectivity in new type polyorganosiloxanes with carboxyl group on the side chain

SummaryOxygen-permselectivity through polyorganosiloxanes with carboxyl group on the side chain is discussed in terms of the differences between the O2, N2 diffusion coefficients or their solubility coefficients. The oxygen-selectivity increases from 2 to 5 with the increase in the carboxyl component of the side chain. Especially the selectivity in the diffusion coefficient is found to more contribute to the oxygenpermselectivity in comparison with that of the solubility coefficient. But the permeation coefficient decreases with the permselectivity.

Tetramethyl-p-silphenylenesiloxanedimethylsiloxane block and graft copolymers as selective permeable membranes

We synthesized tetramethyl-p-silphenylenesiloxane (TMPS)dimethylsiloxane (DMS) copolymers as selective permeable membranes for oxygen and nitrogen, and investigated the relation between their permeability and selectivity and microstructure after preparing some membranes by a solvent casting method. First, we examined the permeability of TMPS/DMS block and graft copolymers (DMS segment length 100) using measurements of dynamic viscoelasticity, crystallinity, melting temperature (Tm) and glass transition temperature (Tg). These measurements showed the permeability to increase by mixing the TMPS and DMS phases, thus disturbing the fold crystallinity of the TMPS phase. Accordingly we investigated the permeability of block copolymers having shorter DMS segment lengths (DMS segment length 40,20). The membranes with mixed microstructures with shorter DMS segment lengths were successfully synthesized and showed excellent permeability. The selectivity also increased by shortening the DMS segment length, the selectivity being affected considerably by the TMPS phase. In particular, one of the copolymers containing 19% DMS (segment length 20) showed high permeability (PO2 = 2.3 × 10−8 cm3 cm/s cm2 cmHg) and high selectivity (α = 3.0).

Facilitated Transport of Molecular Oxygen in Membranes of Macromolecular Cobalt-Porphyrin Complex: Modification of Dual-Mode Transport Model

Abstract Transport of molecular oxygen is facilitated in poly(butyl methacrylate) membranes containing the cobalt(II)-α,α′,α″,α′″-meso-tetrakis(o-pivalamidophenyl)porphyrin-1-methylimidazole (CoPIm) complex which forms oxygen adduct rapidly and reversibly. The facilitated transport of oxygen is studied by modifying a dual-mode transport model for gas permeation. The diffusion coefficient of oxygen via the fixed CoPIm complexes (Langmuir mode) is assumed to depend on oxygen concentration, and the modified dual-mode transport equation is described for the permeation steady state. The modified equation represents the effect of upstream oxygen pressure on the permeability. The oxygen permeation behavior through the macromolecular-metal complex membrane is discussed.

Synthesis of silica gels containing imidazole groups and their binding affinity for methyl orange in water

Abstract Silica gels containing imidazole groups or hexyl groups whose compositions are well controlled have been prepared. The imidazole group in the gel was quaternized with C 4 H 9 Br, C 6 H 13 Br or C 12 H 25 Br to obtain gels that are charged and have an alkyl chain. Their binding affinities for methyl orange in water were then investigated. We aimed to clarify the relation between the structure of the gel and its binding behaviour for small molecules in water. So the binding affinities of the unquaternized and quaternized gels were compared for methyl orange in water at various temperatures and we obtained the thermodynamic parameters for this binding. It was found that in silica gel the alkyl chain that is bound chemically to the charged site is very efficient for binding the dye in water.