• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1521-1525
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• 2009

Thermosensitive block copolymers of ethylene oxide and N-isopropylacrylamide (NIPAM) were synthesized. A five armed star shape oligo(ethylene oxide) initiator with a cyclotriphosphazene core was prepared and used for the atom transfer radical polymerization (ATRP) of NIPAM. The lower critical solution temperatures (LCSTs) of the copolymers were 36 to 46 ${^{\circ}C}$, higher than that of PNIPAM (32 ${^{\circ}C}$), depending on their molecular weights. The copolymers were soluble in water below the LCSTs but formed micelles above the LCSTs. The thermosensitive micellization behaviors of the polymers were investigated by fluorescence spectroscopy. With increasing the temperature of an aqueous solution of P2 and pyrene above the LCST, the peak of 333 nm red-shifted to appear around 339 nm and its intensity increased significantly, indicating the micelle formation. The transfer of pyrene into the micelles was also confirmed by a confocal laser scanning microscope. The fluorescence image obtained from P2 in an aqueous pyrene solution exhibited a green emission resulting from the pyrene transferred into the micelles. Salt effects on the solubility of the copolymers in an aqueous solution were investigated. The LCST of P2 decreased sharply as the concentration of sodium chloride increased, while decreased slowly with potassium chloride.

• Macromolecular Research
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• 제16권2호
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• pp.169-177
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• 2008

This paper reports a facile synthesis of new water-soluble poly(ethylene oxide) (PEO)-based amphiphilic block copolymers showing pH sensitive phase transition behaviors. The copolymers were prepared by atom transfer radical polymerization (ATRP) of methacrylamide type of monomers carrying a sulfonamide group using a PEO-based macroinitiator and a Cu(I)Br/$Me_6TREN$ catalytic system in aqueous media. The resulting polymers were characterized by a combination of $^1H$-NMR, size exclusion chromatography, and UV/Visible spectrophotometeric analysis. The micellization of the block copolymers as a drug-loading mechanism in aqueous media using fluorescein salt was examined as a function of pH. The stable micelle formation and its loading efficacy suggest that the block copolymers can be used as precursors for drug-nanocontainers.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.330-342
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• 2003

The formation of emulsions and micelles in water/ceramide PC104/CholE $O_{20}$/C$_{16}$E $O_{20}$ and water/ceramide PC104/CholE $O_{20}$ mixtures was investigated through the phase behavior studies. The phase diagrams showed the existence of micelle and emulsion regions in both systems. The mixed surfactant system (CholE $O_{20}$/C$_{16}$E $O_{20}$) showed the wider micellar and emulsion regions than the single surfactant system (CholE $O_{20}$). From FT-IR measurements, it was found that the polyoxyethylene (POE) groups of surfactants formed the hydrogen bonds with amido carbonyl group in ceramide PC104. This result indicated that the hydrophilic part (EO) of surfactants could stabilize the lamellar structure and emulsion of ceramide PC104. The mixed surfactant system (CholE $O_{20}$/C$_{16}$E $O_{20}$) resulted in the smaller emulsion droplet size due to the effect of curvature at the interface, thus further increasing emulsion stability. With the penetration of $C_{16}$E $O_{20}$into the interfacial layer of surfactants in emulsion, the curvature of the interface might be altered for the formation of smaller emulsion droplets. The mixed surfactant system could incorporate up to 4 wt. % of ceramide PC104 into emulsion more than single surfactant system.ystem.m.

• 대한화학회지
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• 제42권4호
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• pp.416-421
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• 1998

귀금속-티아크라운에테르 착물들의 역상 이온쌍 고성능 액체크로마토그래피(RPIP-HPLC)용리 거동에서 이온쌍 시약의 농도와 리간드 종류 효과를 연구하였다. 귀금속 이온 분석의 선택성은 사용한 티아크라운에테르의 고리를 구성하는 원자들의 수가 작을수록 좋았고, 귀금속-티아크라운에테르 착물의 용리 메카니즘은 이동상 중 이온쌍 시약인 도데실술폰산나트륨염(SDS)의 농도가 10 mM 이하일 경우 이온쌍 형성 메카니즘으로, 10 mM 이상일 경우 미쎌 형성 메카니즘으로 설명되었다. 결론적으로 몇 가지 귀금속-티아크라운에테르 착물들을 최적 조건에서 성공적으로 분리하였고, 흑백사진 정착액 중 Ag(Ⅰ) 이온 분리와 정량에 유용함을 증명하였다.

• 공업화학
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• 제8권6호
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• pp.1041-1047
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• 1997

$\omega$-Phenylalkylamine salt의 존재하에서 sodium dodecyl sulfate (SDS)의 임계 미셀농도(CMC)를 전기전도도법으로 구하였다. 유기염의 alky기의 길이가 길어짐에 따라 CMC는 감소하는 경향을 보여주었다. 유기첨가제의 존재하에서 $18^{\circ}C-50^{\circ}C$의 온도 범위에서 SDS의 미셀화 과정에 수반되는 열역학적 파라메터를 구하였다. 이 온도 범위에서 SDS의 미셀화 자유에너지 (${\Delta}G_m^{\circ}$)는 음의 값을 나타내며 미셀화 엔트로피(${\Delta}S_m^{\circ}$)는 큰 양의 값을 나타내었으며 미셀화 엔탈피(${\Delta}H_m^{\circ}$)는 낮은 온도($18^{\circ}C$)에서는 양의 값을 나타내지만 높은 온도($>25^{\circ}C$)에서는 음의 값을 나타내었다. 미셀화는 자발적인 상전이 현상임을 알 수 있었다. 이들 열역학적 파라메터들은 유기염의 소수성 부분의 길이가 길어짐에 따라 감소하는 경향을 보여주었다. 비전도도 값의 차(${\Delta}\kappa$)가 유기염의 mol 비가 증가할수록 큰 값을 나타내었다. 그러므로 유기염의 소수성 부분의 길이가 길어질수록 유기염들은 더 쉽게 SDS 미셀내의 palisade층까지 깊이 침투하여 안정한 혼합 미셀을 형성함을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.368-372
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• 2006

The cobalt titanate, $CoTiO_3$ nanoparticles have been prepared by calcinations of precursor obtained from a mixture of $TiO_2$ and $Co(OH)_2$ in aqueous cetyltrimethylammonium bromide (CTAB) solution. The nanoparticles were investigated with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric/differential thermal analysis (TGA/DTA) to determine the crystallite size and the phase composition. The spectroscopic characterizations of these nanoparticles were also done with UV-Vis spectroscopy and FT-Raman spectroscopy. XRD patterns show that $CoTiO_3$ phase was formed at calcinations temperature above 600 ${^{\circ}C}$. UV-Vis absorption spectra indicate that the $CoTiO_3$ nanoparticles have significant red shift to the visible region (400-700 nm) with $\lambda_{max}$ = 500 nm compared to pure $TiO_2$ powder ($\lambda_{max}$ = 320 nm). The new absorption peaks (absorption at 696, 604, 520, 478,456, 383, 336, 267, 238, 208 $c m ^{-1}$), which were not appeared in FT-Raman spectra of P-25, also confirm the formation of Ti-O-Co bonds at above 600 ${^{\circ}C}$ and just not the mixtures of titanium dioxide with cobalt oxides.

• 상하수도학회지
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• 제28권4호
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• pp.419-429
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• 2014

Recent studies have been reported the presence of Endocrine Disrupting Compounds, Pharmaceuticals and Personal Care Products (EDC/PPCPs) in surface and wastewater, which could potentially affect to the complicate behavior in coupled presence of nano-colloid particles and surfactants (adsorption, dispersion, and partitioning). In this study, the adsorption of EDC/PPCPs by Single Walled Carbon Nanotubes (SWNTs) as a representative of nano-particles in cationic surfactant solutions were investigated. Hydrophobic interactions (${\pi}-{\pi}$ Electron Donor-Acceptor) have been reported as a potential adsorption mechanisms for EDC/PPCPs onto SWNTs. Generally, the adsorptive capacity of the relatively hydrophobic EDC/PPCPs onto SWNTs decreased in the presence of cationic surfactant (Cetyltrimethyl Ammonium Bromide, CTAB). This study revealed that the competitive adsorption occurred between CTAB cations and EDC/PPCPs by occupying the available SWNT surface (CTAB adsorption onto SWNTs shows five-regime and maximum adsorption capacity of 370.4 mg/g by applying the BET isotherm). The adsorption capacity of $17{\alpha}$-ethinyl estradiol (EE2) on SWNT showed the decrease of 48% in the presence of CTAB. However, the adsorbed naproxen (NAP) surely increased by forming hemimicelles and resulted in a favorable media formation for NAP partition to increase SWNTs adsorption capacity. The adsorbed NAP increased from 24 to 82.9 mg/g after the interaction of CTAB with NAP. The competitive adsorption for EDC/PPCPs onto SWNTs is likely to be a key factor in the presence of cationic surfactant, however, NAP adsorption showed a slight competition through $CH_3-CH_3$ interaction by forming hemimicelles on SWNT surface.

• Journal of Electrochemical Science and Technology
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• 제11권2호
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• pp.148-154
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• 2020

Highly ordered mesoporous manganese oxide films were electrodeposited onto indium tin oxide coated (ITO) glass using sodium dodecyl sulfate (SDS) and ethylene glycol (EG) which were used as a templating agent and stabilizer for the formation of micelle, respectively. The manganese oxide films synthesized with surfactant templating exhibited a highly mesoporous structure with a long-range order, which was confirmed by SAXRD and TEM analysis. The unique porous structure offers a more favorable diffusion pathway for electrolyte transportation and excellent ionic conductivity. Among the synthesized samples, Mn₂O₃-SDS+EG exhibited the best electrochemical performance for a supercapacitor in the wide range of scan rate, which was attributed to the well-developed mesoporous structure. The Mn₂O₃ prepared with SDS and EG displayed an outstanding capacitance of 72.04 F g^-1, which outperform non-porous Mn₂O₃ (32.13 F g^-1) at a scan rate of 10 mV s^-1.

• 한국응용과학기술학회지
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• 제7권1호
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• pp.13-24
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• 1990

2-N,N,N-trimethyl ammonia decanoate, 2-N,N,N-trimethyl ammonio dodecanoate, 2-N,N,N-trimethyl ammonia tetradecanoate and 2-N,N,N-hexadecanoate with in straight long chain alkyl carboxybetaines, and N-decyl N,N-dimethyl ammonio ethanoate, N-dodecyl N,N-dimethyl ammonia ethanoate, N-tetradecyl N,N-dimethyl ammonia ethanoate and N-hexadecyl N,N-dimethyl ammonia ethanoate with in nitrogen-straight long chain alkyl carboxy betaines measured respectively surface tensions by the stalagmometer method at various temperature, also their critical micelle concentration were evaluated. In micellization, the contribution of standard free energy change(${\Delta}G^{\circ}m$), standard enthalpy change(${\Delta}H^{\circ}m$) and standard entropy change (${\Delta}S^{\circ}m$), have been calculated, with increasing temperature. ${\Delta}H^{\circ}m$ changes from negative, and a similar change in the sign of ${\Delta}H^{\circ}m$ is observed with increasing chain length at $25^{\circ}C$, while the entropy of micellization, ${\Delta}S^{\circ}m$ is positive over the temperature range studied, it becomes less so at higher temperatures. Estimates of the enthalpy and entropy contribution attributable to the ion head group and alkyl chain have been made. The enthalpy and entropy change, per methylene group increase respectively with increasing chain length the result are discussed in terms of current theories of micellization.

• Journal of Pharmaceutical Investigation
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• 제38권6호
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• pp.393-398
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• 2008

A propofol delivery system was prepared using two biocompatible polymeric surfactants, poloxamer 407 and PEG 400. The nanoparticular stability of the micellar system was evaluated in terms of temperature change, storage time and composition. The particle size of the system was slightly increased with elevating temperature from $4^{\circ}C$ to $25^{\circ}C$, but its distribution was unimodal. At $40^{\circ}C$, the system presented a bimodal particle size distribution and the increase in the fraction of particles larger than 15 nm. This result might be due to the expansion of the nanoparticles through micellar swelling at the high temperature. It was found that propofol was gradually come out of the system, stored for a month at three different temperatures (4, 25 and $40^{\circ}C$). The drug loss was apparently dependent on temperature and the system composition. Increasing temperature induced the acceleration of the drug loss of $7{\sim}10%$ at $4^{\circ}C$ and $14{\sim}16 %$ at $40^{\circ}C$. This may be owing to the high diffusivity resulting from the swelling of the hydrophilic surface of the nanoparticle at high temperature. However, the addition of PEG 400 to the system led to the reduction of the drug loss. This result is associated with the previous investigation that PEG coverage decreased diffusion coefficient because of the formation of the denser structure on the surface of nanoparticulate. Nevertheless, the limited amount of PEG, less than 2% (w/v), should be used to prevent the precipitation and discoloration of the system.