• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1843-1845
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• 1999

We have investigated the dielectric characteristics of palmitic acid(PA), stearic acid (SA) and arachidic acid(AA) Langmuir-Blodgett(LB) films because these fatty acid systems have a same hydrophilic group and a different hydrophobic one (alkyl chain length). In this work. fatty acid systems were used as LB films and the status of the deposited films was confirmed by evaluating the transfer ratio. the UV absorption and the capacitance. Also, the dielectric characteristics such as the frequency-capacitance characteristics and the dielectric dispersion and absorption characteristics of PA, SA and AA through-plane were measured. The relative dielectric constants of PA, SA and AA LB films were about $2.6\sim4.6$, $2.4\sim4.1$ and $2.2\sim3.8$, respectively. That is, the relative dielectric constants were decreased in proportion to the chain length of methylene group. And, the dielectric dispersion and absorption of each fatty acid LB films have arisen from spontaneous polarization of dipole polarization in the range of $10^4\sim10^5[Hz]$.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1711-1716
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• 2005

Fragmentations and ion-molecule reactions of ionized cyclohexane propionic acid and cyclohexane butyric acid were studied using FTMS and theoretical calculations. The difference in bond dissociation depending on the aliphatic chain length was investigated and mechanisms for the possible rearrangements depending on the aliphatic carbon length were suggested. The most abundant fragment ion of the ionized cyclohexane propionic acid was c-$C_6H_{11}CH_2\;^+$ formed from the molecular ion by the direct C-C bond cleavage, while that of the ionized cyclohexane butyric acid was c-$C_6H_9C(OH)=OH^+$ formed by rearrangement of the molecular ion from the acid to diol form and loss of propyl radical. Stabilities of the radical and distonic ions of $C_nH_{2n}O^{+\bullet}$ formed from the molecular ion were compared. Protonated molecules were dissociated into smaller ions by losing one or two water molecules. The $[nM + H]^+$, $[nM + H - H_2O]^+$, and $[nM + H - 2H_2O]^+$ with n = 2 and 3 were generated by solvation with the neutral molecules in the ICR cell at long ion trapping time.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.405-407
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• 2008

Functionalized SAB-15 samples by octadecyltrimethoxysilane (OTC) were studied by 13C magic angle spinning (MAS) cross polarization (CP) nuclear magnetic resonance (NMR) spectroscopy. In the SBA-15 sample fully functionalized by 3-aminopropyltrimethoxysilane (APS) and OTC in 1:1 molar ratio, octadecyl chains were observed to have, on average, more trans conformation than those in the SBA-15 samples fully modified by OTC only. Our results confirm that long chain molecules tend to organize themselves better in the co-presence of short chain molecules on the surface of mesoporous materials by packing of the different length chains in an interdigitized fashion even when the short chains are long enough to have three carbons and a functional group at the ends. In addition, our results indicate that solid-state 13C CP MAS NMR spectroscopy is a simple and non-destructive method to probe the molecular structures of the domains composed of long alkyl chains.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.72-79
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• 2018

Hybrid F2HX surfactants bearing a sulfate moiety and both hydrocarbon and fluorocarbon chains were prepared by the reaction of alkyl glycidyl ethers with fluoro-alcohol, and subsequent sulfation. The fluorocarbon number in F2HX was fixed at the shortest number possible (i.e., 2), while the hydrocarbon number (X) in the second chain was varied between 2, 4, 6, and 8. Their surface-active properties and emulsion stabilities were systematically estimated as a function of the X. Among them, F2H8 exhibited the optimal surfactant performance, which was comparable to previously reported surfactants and it was successfully applied in the emulsion polymerization of vinylidene fluoride.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.738-743
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• 1998

Thirty six 5,8-dimethoxy-1,4-naphthoquinone derivatives, which bear unsaturated alkyl side chain with ester bond, were synthesized and tested cytotoxic activity on L1210 cells a nd antitumor activity against ICR mice bearing S-180 cells. It could be recognized that the cytotoxicities of naphthoquinones with R1, being methyl and propyl (IV1~24) were not enhanced by replacing the alkanoyls with alkenoyls. In contrast, the introduction of the alkenoyl moieties on the compounds with $R_1$=hexyl (IV25~36) resulted in the enhancement of their cytotoxicities. Replacement of alkanoyl group with an alkenoyl group generally increased the T/C value of the mice bearing S-180 cells.

• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1545-1553
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• 2008

Using a one-pot reaction technique, monodisperse $\gamma-Fe_2O_3$ nanoparticles were prepared by thermal decomposition of Fe$(CO)_5$ in the presence of a long alkyl chain terminated dendron surfactant. The size of the particles is controlled by adjusting the concentration of the dendron ligands in the reaction solution. Spherical, 2 nm sized nanoparticles were obtained with a 3:1 ratio of dendrons to Fe$(CO)_5$, while 4.6 nm sized particles were formed with a 1:3 ratio. Superparamagetic properties of 2 nm, 4 nm, and 4.6 nm sized particles were measured using a SQUID magnetometer.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1096-1098
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• 1999

MCM-41 type spherical mesoporous silica material was synthesized, under basic conditions, in the presence of cationic surfactant as templating species. The cationic surfactants used in this experiment were octyltrimethylammonium bromide, dodecyltrimetylammonium bromide, cetyltrimethylammonium bromide, octadecyltrimethyammonium bromide and cetylpyridium bromide. Specific surface area of spherical MCM-41 was as high as $1500m^2/g$ and the pore size decreased with increasing alkyl chain length of surfactant.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.39-45
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• 1998

In recent years, there has been considerable interest in the development of new functional surfactant including new type of anionic surfactants. Anionic surfactants, ${\alpha}-sulfo$ fatty acids that straight long chain alkyl group having from 12 to 18 carbon atoms, were synthesized with sulfur trioxide-dioxane complex to good yield. Xylitol ${\alpha}-sulfo$ fatty acid esters were obtained by reaction that the acetification and esterification of xylitol, by addition reaction with sodium chloride and hydrolysis respectively. These compounds were a new group of destructible surfactants which readily hydrolyzed and oxidized in natural water reservoirs. Physical properties of these new compounds involved surface tension, critical micelle concentration(cmc), foaming power, emulsion power, and hydrolysis properties, were measured. The cmc values of the compounds by ring method were assumed to $7.0{\times}10^{-3}{\sim}3.0{\times}10^{-2}mol/{\ell}$ range and surface tensions at cmc were $25{\sim}31dyne/cm$ respectively.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.1
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• pp.91-98
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• 1991

Electrical conductivity of poly (3-alkylthiophene) derivatives with substituted long alkyl chain such as poly (3-butylthiophene), poly (3-hexylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), and poly (3-docosylthiophene) increases with increasing temperature. However, after attaining a maxiumum value, it decreases with further temperature increase. Hysteresis is also observed in the temperature dependence of conductivity and absorption spectra. The absorption spectra also changes rapidly at the phase transition. These phenomena are discussed in terms of the increase of the energy band gap in the liquid states due to the decrease of co-planarity of thiophene rings accompanied by remarkable conformation changes.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.76-79
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• 2004

Nickel chloride coated protein chip plate was developed by using a spin coating method. The ability of histidine tagged protein adsorption was investigated at various solvents. The surface of plate has a large aggregated nickel complex with high density in water. However, the surface of plate has a very small size of aggregated nickel complex with low density in isopropanol. The ability of protein adsorption decreased as increasing the size of alkyl chain in various alcohol solvents. The mechanism on the ability of protein adsorption at the plate surface is discussed.