• 한국응용과학기술학회지
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• 제38권4호
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• pp.994-1002
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• 2021

양이온성 계면활성제(DTAB, TTAB 및 CTAB)에 의한 4-할로겐화 아닐린의 가용화상수(K_s)값을 UV-Vis법으로 측정하였다. 그 결과, 모든 아닐린 유도체에서 온도의 증가에 따라 K_s은 모두 감소하였으며, 할로겐 치환기의 반지름과 계면활성제의 소수기길이를 증가할수록 K_s값은 더욱 증가하였다. 이들 가용화상수 값을 이용하여 계산한 ΔG^o와 ΔH^o값은 측정한 범위 내에서 모두 음의 값을 그리고 ΔS^o값은 모두 양의 값을 나타내었다. 모든 아닐린 유도체에서 온도를 증가함에 따라 ΔG^o값은 감소하는 경향을 보였다. 그러나 온도의 증가에 따라 ΔH^o와 ΔS^o값은 모두 증가하는 경향을 보였다. 한편 할로겐치환기의 반지름을 증가할수록 이들 열역학 함수 값들은 대체적으로 감소하는 경향을 보였다. 그러나 계면활성제의 소수기길이를 증가하였을 때 이들 열역학 함수 값은 아닐린유도체의 종류에 따라 다르지만 대체적으로 증가하는 경향을 보였다. 이런 열역학 함수 값들의 변화로부터 4-할로겐화 아닐린과 미셀과의 상호작용의 종류와 세기를 그리고 이들이 미셀 내에서 가용화되는 위치를 추정할 수 있었다.

• 대한화학회지
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• 제37권5호
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• pp.496-502
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• 1993

Spectrophotometric Determination of Rare Earths by Ternary CompleMTB와 희토류 원소들 간에 이루어진 착물에 cetylpyridinium chloride(CPC), dodecyltrimethylammonium bromide(DTMAB), cetyltrimethylammonium bromide (CTMAB), Triton X-100 등의 계면활성제를 가하였을 때의 흡광도 변화로부터 이들 원소를 정량하는 방법과 조성비를 연구하였다. 양이온 계면활성제들인 CPC, DTMAB, CTMAB 등이 있을 때 MTB와 희토류 원소들간의 흡광도가 계면활성제들이 없을 때보다 더 컸다. 가장 큰 흡광도 증가는 CPC에서 얻어졌으므로 희토류 정량에는 이를 선택하였다. REE-MTB-CPC 삼성분 착물은 650nm에서 최대흡광도를 갖고 0~100 ng/ml 범위에서 Beer 법칙에 따르고 몰흡광계수는 $6.6{\sim}9.4{\times}10^4\;mol^{-1}l\;cm^{-1}$이다.

• Journal of Pharmaceutical Investigation
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• 제33권2호
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• pp.121-127
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• 2003

The objective of this study was to solidify the simvastatin self-microemulsifying drug delivery system (SMEDDS) and to improve the encapsulation efficiency of solidified alginate beads using sodium alginate. Typical simvastatin SMEDDS was composed of various oils, surfactants and cosurfactants. Also solidified-alginate beads was prepared by crosslinking liquid emulsion mixtures containing sodium alginate and other excipients (cetylpyridinum chloride (CP-Cl), hydroxypropyl methylcellulose, starch and so on). in $CaCl_2$ solution, it has been investigated that the drug release pattern and encapsulation efficiency were varied with the ratio of cationic lipid (CP-Cl). Solidified sodium alginate beads containing simvastatin SMEDDS were redispersed into media without re-aggregation. Oil droplet size of redispersed solidified-beads in media produced smaller than the initial size. The density of beads and drug loading amount were increased with increasing cationic lipid content. These systems have advantages of storage stability and predictability of drug release rate.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.667-674
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• 2007

Phase behavior for the mixed aqueous surfactant systems of cationic octadecyl trimethyl ammonium chloride (OTAC)/anionic ammonium dodecyl sulfate (ADS)/water was examined. Below the total surfactant concentrations of 1.5 m molal, mixed micelles were formed. At the total surfactant concentrations higher than 1.5 m molal, there appeared a region where mixed micelles and vesicles coexist. As the surfactant concentration increased, the systems looked very turbid and much more vesicles were observed. The vesicles were spontaneously formed in this system and their existence was observed by negative-staining transmission electron microscopy (TEM), small-angle neutron scattering (SANS) and encapsulation efficiency of dye. The vesicle region was where the molar fraction α of ADS to the total mixed surfactant was from 0.1 to 0.7 and the total surfactant concentration was above 5 × 10-4 molality. The size and structure of the vesicles were determined from the TEM microphotographs and the SANS data. Their diameter ranged from 450 nm to 120μm and decreased with increasing total surfactant concentration. The lamellar thickness also decreased from 15 nm to 5 nm with increasing surfactant concentration and this may be responsible for the decrease in vesicle size with the surfactant concentration. The stability of vesicles was examined by UV spectroscopy and zeta potentiometry. The vesicles displayed long-term stability, as UV absorbance spectra remained unchanged over two months. The zeta potentials of the vesicles were large in magnitude (40-70 mV) and the observed longterm stability of the vesicles may be attributed to such high ζ potentials.

• 공업화학
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• 제31권4호
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• pp.429-437
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• 2020

본 연구에서는 이소소르비드를 이용하여 양이온 제미니 계면활성제의 알킬기가 C₁₀~C₁₆개로 변화시키면서 합성하였다. 합성한 양이온 제미니 계면활성제에 대한 c.m.c는 5.13 × 10^-4~1.62 × 10^-4 mol/L의 범위에서 표면장력은 31.86~39.24 dyne/cm로 측정되었으며, 알킬기의 길이가 길어질수록 표면장력이 상승하였다. 또한, 흡착량는 감소하여 계면에 흡착된 계면활성제의 분자 당 차지하는 면적이 커지게 되면서 공기-물 계면에 기포력이 감소하였다. 벤젠에서의 유화력은 8 h이 지난 후 60 ± 5% 이상의 유화력이 유지되었으며, 대두유에서의 유화력이 50 ± 5% 이상 감소하는 경향을 보였다. 소수성이 강한 벤젠에서 우수하며, 유상과 수상의 프리에멀젼 제조 시, 유화 안정성이 일정한 시간 이상 유지되는 것을 확인할 수 있었다. 항균력은 Escherichia coli (E.coli)과 Staphylococcus aureus에서의 clean zone의 크기가 증가하여 합성한 양이온 제미니 계면활성제의 소수성 사슬의 길이에 의존하였다.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1562-1566
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• 2006

Mesoporous silica films with three different pore sizes were prepared by using cationic surfactant, non-ionic surfactant, or triblock copolymer as structure directing agents with tetramethylorthosilicate as silica source in order to control the pore size and wall thickness. They were synthesized by an evaporation-induced self-assembly process and spin-coated on Si wafer. Mesoporous silica films with three different pore sizes of 2.9, 4.6, and 6.6 nm and wall thickness ranging from $\sim$1 to $\sim$3 nm were prepared by using three different surfactants. These materials were optically transparent mesoporous silica films and crack free when thickness was less than 1 m m. The photoluminescence spectra found in the visible range were peaked at higher energy for smaller pore and thinner wall sized materials, consistent with the quantum confinement effect within the nano-sized walls of the silica pores.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1729-1734
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• 2007

The electrochemical behaviors of estrone in the presence of various surfactants were examined with great details. It is found that a cationic surfactant, cetyltrimethylammonium bromide (CTAB), obviously facilitates the electro-oxidation of estrone at carbon paste electrode (CPE) from the significant peak current enhancement and the negative shift of peak potential. Additionally, chronocoulometry and electrochemical impedance spectroscopy (EIS) were also used for further investigation of the electrode process of estrone, indicating that low concentration of CTAB exhibits excellent enhancement effects on the electrochemical oxidation of estrone, greatly enhances the diffusion coefficient and the electron transfer rate. Based on this, an electrochemical method was proposed for the determination of estrone. The oxidation peak current is proportional to the concentration of estrone in the ranges over 9.0 × 10?8 - 8.0 × 10?6 mol/L, and a low detection limit of 4.0 × 10?8 mol/L was obtained for 180s accumulation at open circuit (S/N = 3). Finally, this proposed method was demonstrated using estrone tablets with good satisfaction.

• 공업화학
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• 제5권1호
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• pp.114-120
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• 1994

DCI (dichlorolsocyanuric acid sodium salt)에 의한 PNPDPP (p-nitrophenyldiphenylphosphate)의 미셀 내에서의 분해 반응을 pH 8.0 borate 완충용액에서 속도론적으로 살펴보았다. 양이온성 계면활성제인 CTAC (cetyltrimethylammonium chloride) 또는 CTAB (cetyltrimethylammonium bromide)를 첨가하면 반응은 빠르게 촉진되었으며, 특히 CTAB의 경우는 DCI의 N-Cl 결합이 N-Br 결합으로 전환되어 반응이 진행되었다.

• 대한기계학회논문집A
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• 제30권2호
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• pp.179-186
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• 2006

Dielectrophoresis has received considerable attention for separating nanotubes according to electronic types. Here we examine the effects of surface conductivity of semiconducting single-walled carbon nanotubes (SWNT), induced by ionic surfactants, on the sign of dielectrophoretic force. The crossover frequency of semiconducting SWNT increases rapidly as the conductivity ratio between the particle and medium increases, leading to an incomplete separation of ionic surfactant suspended SWNT at an electric field frequency of 10 MHz. The surface charge of SWNT is neutralized by an equimolar mixture of anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyltrimenthylammonium bromide (CTAB), resulting in negative dielectrophoresis of semiconducting species at 10 MHz. A comparative Raman spectroscopy study shows a nearly complete separation of metallic SWNT.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1737-1741
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• 2008

Dielectrophoretic behavior of semiconducting single-walled carbon nanotubes(SWNT) was investigated theoretically and experimentally. The surface conductance of nanotubes was modulated using anionic and cationic surfactant mixtures. The experimental results indicate that dielectrophoretic behavior of SWNT highly depends on the procedure of mixing two opposite-charged surfactants. Clausius-Mossotti factor was calculated by measuring zeta potentials and solution conductivity. Raman spectroscopy was used to characterize the dielectrophoretically deposited nanotubes arrary. We found that metallic nanotubes were selectively separated from the nanotubes suspension, resulting from modulation of surface conductance of semiconducting SWNT.