• Analytical Science and Technology
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• v.8 no.1
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• pp.33-40
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• 1995

Only trace amounts of hydroxide ion can be extracted from aqueous phase into organic phase by Tetra-n-Butyl Ammonium Chloride(TBAC). Addition of small amounts of primary alcohols, particularly certain dials, dramatically changes the behavior of Phase Transfer Catalysis systems, and surprising amounts of base can be found in the organic phase. Quantitative measurements were carried out for the extraction amounts of primary alkoxides, secondary alkoxides, and diol anions into organic phase. On the other hand, the selectivity constants for extraction of primary alcohols and benzylalcohol could be separated to the equilibrium constants of the ion pairs such as $Q^+RO^-$ and $Q^+Cl^-$ in the aqueous and organic phases and this distribution coefficients between phases on anions respectively. In a word, the colligated property for the selectivity of $Q^+RO^-$ in which $Q^+$ is quaternary cation and $RO^-$ alkoxide ion could be discussed in more detail by using of the corresponding free energies to the various constants mentioned.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.496-501
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• 2005

The thermal degradation of ABS in the presence of iron-based metal catalysts has been studied by thermogravimetric analysis (TGA). The reaction of iron-based metal catalysts (ferric nitrate nonahydrate, ammonium ferric sulfate dodecahydrate, iron sulfate hydrate, ammonium ferric oxalate, iron(II) acetate, iron(II) acetylacetonate and ferric chloride) with ABS has been found to occur during the thermal degradation of ABS. In a nitrogen atmosphere, char formation was observed, and at $600^{\circ}C$ approximately 3~23 wt% of the reaction product was non-volatile char. The resulting enhancement of char formation in a nitrogen atmosphere has been primarily due to the catalytic crosslinking effect of iron-based metal catalysts. On the other hand, char formation of ABS in air at high temperature by iron-based metal catalyst was unsuccessful due to the oxidative degradation of the char.

• Macromolecular Research
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• v.16 no.8
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• pp.725-733
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• 2008

Polyimide (PI) multilayer thin films were prepared by spin-coating from a poly(amic acid) (PAA) and poly(amic acid) ammonium salt (PAAS). PI was prepared from pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (ODA) PAA. Different compositions of PAAS were prepared by incorporating triethylamine (TEA) into PMDA-ODA PAA in dimethylacetamide. PI multilayer thin films were spin-coated from PMDA-ODA PAA and PAAS. The PAAS comprising cationic and anionic moieties were spherical with a particle size of $20{\sim}40\;nm$. Some particles showed layers with ammonium salts, despite poor ordering. Too much salt obstructed the interaction between the polymer chains and caused phase separation. A small amount of salt did not affect the interactions of the interlayer structure but did interrupt the stacking between chains. Thermogravimetric analysis (TGA) showed that the average decomposition temperature of the thin films was $611^{\circ}C$. All the films showed almost single-step, thermal decomposition behavior. The nanostructure of the multilayer thin films was confirmed by X -ray reflectivity (XRR). The LF 43 film, which was prepared with a 4:3 molar ratio of PMDA and ODA, was comprised of uniformly spherical PAAS particles that influenced the nanostructure of the interlayer by increasing the interaction forces. This result was supported by the atomic force microscopy (AFM) data. It was concluded that the relationship between the uniformity of the PAAS particle shapes and the interaction between the layers affected the optical and thermal properties of PI layered films.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.325-329
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• 2002

In this study, the dependency of the behavior of propagating front on the reaction condition in frontal polymerization reaction has been studied. We have used some multifunctional acrylates as a monomer and ammonium persulfate as an initiator for the polymerization reactions. In frontal polymerization, a method of producing polymeric materials via a thermal front that propagates through the unreacted monomer/initiator solution, the behavior of self propagating front shows various dynamic patterns depending on the reaction condition. We have obtained some spin modes of propagating front in the number of 'hot spots' or 'spin heads' by changing the reaction condition. The effect of the reactor tube diameter on the mode of propagating front has also been studied by using some reactor tubes with different size of tube diameter and it has been examined in some detail by adopting an experimental method of two-tubes system.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1891-1894
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• 2005

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1260-1264
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• 1997

The phase-transfer reagent (PTC), ethyl tri-n-octylammonium bromide (ETABr), strongly catalyzes the reaction of p-nitrophenyldiphenylphosphinate (p-NPDPIN) with benzimidazole (BI) and its anion (BI-). In ETABr solutions, the dephosphorylation reactions exhibit higer than first order kinetics with respect to the nucleophile, BI, and ETABr, suggesting that reactions are occuring in small aggregates of the three species including the substrate, whereas the reaction of p-NPDPIN with OH- is not catalyzed by ETABr. This behavior for the drastic rate-enhancement of the dephosphorylation is refered as 'aggregation complex model' for reactions of hydrophobic organic phosphinates with benzimidazole in hydrophobic quarternary ammonium salt solutions.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.297.1-297.1
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• 2003

Organic solvent-based enteric coating technology using hydroxypropyl methylcellulose phthalate (HPMCP) has been developed for many years due to low water solubility of HPMCP. In this work, aqueous HPMCP nanoparticles (HPMCP-NPs) were prepared by neutralization emulsification method using HPMCP powder and ammonium hydroxide (NH40H) in the absence of any organic solvent and emulsifier. (omitted)

• Journal of Powder Materials
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• v.23 no.5
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• pp.353-357
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• 2016

In this study, $TiO_2$ powders are synthesized from ammonium hexafluoride titanate (AHFT, $(NH_4)_2TiF_6$) as a precursor by heat treatment. First, we evaluate the physical properties of AHFT using X-ray diffraction (XRD), particle size analysis (PSA), thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). Then, to prepare the $TiO_2$ powders, is heat-treated at $300-1300^{\circ}C$ for 1 h. The ratio of anatase to rutile phase in $TiO_2$ is estimated by XRD. The anatase phase forms at $500^{\circ}C$ and phase transformation to the rutile phase occurs at $1200^{\circ}C$. Increase in the particle size is observed upon increasing the reaction temperature, and the phase ratio of the rutile phase is determined from a comparison with the calculated XRD data. Thus, we show that anatase and rutile $TiO_2$ powders could be synthesized using AHFT as a raw material, and the obtained data are utilized for developing a new process for producing high-quality $TiO_2$ powder.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.803-809
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• 2005

Cerium ammonium nitrate (CAN) and nitric acid was used an etchant and an additive for Ru etching and polishing. pH and Eh values of the CAN and nitric acid added chemical solution satisfied the Ru etching condition. The etch rate increased linearly as the concentration of CAN increased. Nitric acid added solution had the high etch rate. But micro roughness of etched surfaces was not changed before and after etching, The removal rate of Ru film was the highest in $1wt\%$ abrasive added slurry, and not increased despite the concentration of alumina abrasive increased to $5wt\%$. Even Ru film was polished by only CAN solution due to the friction. The highest removal rate of 120nm/min was obtained in 1 M nitric acid and $1wt\%$ alumina abrasive particles added slurry. The lowest micro roughness value was observed in this slurry after polishing. From the XPS analysis of etched Ru surface, oxide layer was founded on the etched Ru surface. Therefore, Ru was polished by chemical etching of CAN solution and oxide layer abrasion by abrasive particles. From the result of removal rate without abrasive particle, the etching of CAN solution is more dominant to the Ru CMP.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.1 s.60
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• pp.7-10
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• 2007

The interaction between polymers and surfactants was investigated by means of rheological and surface tension measurements. The polymers used in this study were acrylates/$C_{10-30}$ alkyl acrylate crosspolymer (AC) and ammonium acryloyldimethyltaurate/VP copolymer (AV). And the surfactants were PEG-40 hydrogenated castor oil (HC) and polysorbate 60 (P60). HC and P60 made the micelles intervening between AC polymers, resulting in the increase of viscosity. However, HC showed a similar behavior over the wider range of surfactant concentration than P60. Regarding of surface tensions in the same range of surfactant concentration, AC/HC solution showed the area of increasing surface tension with surfactant concentration in contrast to the AC/P60 solution showing no increasing area. It is assumed that the micelles between AC/HC were formed so cooperatively and strongly that the surfactants located at the surface originally moved to the micelles.