Sang Hern Kim

Synthesis and photopolymerization of propenyl ether and epoxy functionalized siloxanes

Abstract The reactive precursors, 1-allyloxy-4(1-propenoxy)butane and allyl-epoxy-ester, were synthesized. The synthesis of propenyl ether and epoxy functionalized siloxanes has been achieved by the controlled, rhodium-catalyzed, chemoselective hydrosilation of allyl ether with various H-functional siloxanes. It was shown that the hydrosilation proceeds exclusively at the allyl ether group of allyloxy-propenoxybutane without participation at the propenyl ether group. The photoinduced cationic polymerization of these monomers was studied and found to be all highly reactive.

Evaluations of Hydrogen Permeation on TiN-20wt.%Co Membrane by Hot Press Sintering

Nowadays, the most promising methods for high purity hydrogen production are membranes separation such as polymer, metal, ceramic and composites. It is well known that Pd and Pd-alloys membranes have excellent properties for hydrogen separation. However, it has hydrogen embrittlement and high cost for practical applications. Therefore, most scientists have studied new materials instead of Pd and Pd-alloys. On the other hand, TiN powders are great in resistance to acids and chemically stable under high operating temperature. In order to get specimens for hydrogen permeation, the TiN powders synthesized were consolidated together with pure Co powders by hot press sintering. During the consolidation of powders at HPS, heating rate was 10K/min and the pressure was 10MPa. It was characterized by XRD, SEM, and BET. Also, we estimated the hydrogen permeability by Sieverts type hydrogen permeation membrane equipment.

Calculation on ion exchange capacity for an ion exchanger using the potentiometric titration

We calculated the characteristics of a phosphoric cation exchanger and studied an accurately computable method for ion exchange capacity for a type of potentiometric titration curve. The ion exchanger was prepared by phosphorylation of a styrene-divinylbenzene copolymer. The ion exchange capacity was 5.7 meq/g. The experimental pK values versus χ in a phosphoric cation exchanger can explain a linear equation. The ΔpK values were obtained from the slope of a linear equation. The ΔpK values were the differences of pK values between the apparent equilibrium constant at complete and zeroth neutralization of the ion exchanger. The experimental pK values at χ = 0.5 (χ:degree of neutralization of ion exchanger) showed good agreement with the theoretical data. When it was titrated with NaOH and Ba(OH)2 solutions, a good agreement between experimental and theoretical pK values for various χ was found in all potentiometric titration curves. The potentiometric titration curve near the inflection point in the case of divalent ions was changed more sharply than that for monovalent ions. The plot of ∂pH/∂g versus g (number of moles of alkali to 1 g of ion exchanger) was fitted to the Lorenzian distribution, from which ion exchange capacity was accurately evaluated.