Sung‐Hwa Oh

The morphology of the sodium salt form of randomly copolymerized polystyrene sulfonate (Na-PSS) in water/THF(99/1v/v) cast onto silicon wafers, was studied by using scanning electron microscope (SEM). The contents of the sulfonate repeat units in Na-PSS were 1.1, 2.4, 4.6, 10.8, and 15.6 mol%. Based on the observed SEM images, the morphology of the Na-PSS changed with increasing ionic group content. For 1.1 and 2.4 mol%, sphere-shaped aggregates were formed with average sizes of 90 nm and of 77 nm, respectively. For 4.6 mol% and 10.8 mol%, 20–30 nm-sized aggregates were close-packed and fused together, resulting a surface with large roughness and ca. 10 nm-sized pores were formed. As the mol% increased to 15.6, the surface became smoother and flat films were formed.

Morphology

Polystyrene

Polystyrene sulfonate

Ionomer

10.1166/jnn.2007.094

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Removal of Free Fatty Acid in used oil on Zeolite Catalysts

한국신재생에너지학회:학술대회논문집 (2008)

Duk‐Rye Chang Sung‐Hwa Oh

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Enthalpy‐Entropy Compensation in Aggregation of Poly(styrene‐co‐sodium methacrylate) Ionomers in Aqueous Solution

Macromolecular Symposia (2007)

Jeong‐A Yu Sung‐Hwa Oh Yu‐Ri Park Joon‐Seop Kim

Abstract Spectroscopic methods were employed to evaluate the thermodynamics of aggregates formation of P(S‐ co ‐MANa) in aqueous solution containing a trace of DMF(0.2 mol%) using pyrene as an optical probe. The mol %s of methacrylate unit in poly(styrene‐ co ‐sodium methacrylate)[P(S‐ co ‐MANa)] were 3.6, 5.0, 6.2 and 9.4. Measurements were made at a series of temperatures in the range 10–80 °C. Based on the temperature dependence of the critical aggregation concentration (CAC) and by the use of van't Hoff equation, thermodynamic parameters were calculated. At low temperature the aggregation is accomplished by a large positive entropy change and a small negative enthalpy changes. As the temperature increases, the magnitude of entropy change becomes smaller and the enthalpy change is more exothermic. Moreover, the changes in enthalpy and entropy compensate each other for all samples we have studied, and the compensation temperature was ∼320 K.

Atmospheric temperature range

Exothermic reaction

10.1002/masy.200750417

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