• Archives of Pharmacal Research
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• 제26권8호
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• pp.653-658
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• 2003

It has been reported that at low temperature region, poloxamers existed as a monomer. Upon warming, an equilibrium between unimers and micelles was established, and finally micelle aggregates were formed at higher temperature. In this study, the fluorescence spectroscopy was used to study the micelle formation of the poloxamer 407 in aqueous solution. The excitation and emission spectra of pyrene, a fluorescence probe, were measured as a function of the concentration of poloxamer 407 and temperature. A blue shift in the emission spectrum and a red shift in the excitation spectrum were observed as pyrene transferred from an aqueous to a hydrophobic micellar environment. From the $I_1/I_3 and I_{339}/I_{333}$ results, critical micelle concentration (cmc) and critical micelle temperature (cmt) were determined. Also, from the fluorescence spectra of the probe molecules such as 8-anilino-1-naphthalene sulfonic acid and 1-pyrenecarboxaldehyde, the blue shift of the $\lambda_{max}$ was observed. These results suggest a decrease in the polarity of the microenvironment around probe because of micelle formation. The poloxamer 407 above cmc strongly complexed with hydrophobic fluorescent probes and the binding constant of complex increased with increasing the hydrophobicity of the probe.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 춘계 총회 및 학술발표회
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• pp.99-101
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• 1998

1. Introduction : The conventional grafting polymerization technique requires chemically reactive groups on the surface as well as on the polymer chains. For this reason, a series of prefunctionalization steps are necessary for covalent grafting. The surface prefunctionalizational technique for grafting can be used to ionization radiation, UV, plasma, ion beam or chemical initiators. Of these techniques, radiation method is one of the useful methods because of uniform and rapid creation of active radical sites without catalytic contamination in grafted samples. If the diffusion of monomer into polymer is large enough to come to the inside of polymer substrate, a homogeneous and uniform grafting reaction can be carried out throughout the whole polymer substrate. Radiation-induced grafting method may attach specific functional moieties to a polymeric substrate, such as preirradiation and simultaneous irradiation. The former is irradiated at backbone polymer in vacuum or nitrogen gas and air, and then subsequent monomer grafting by trapped or peroxy radicals, while the latter is irradiated at backbone polymer in the presence of the monomer. Therefore, radiation-induced polymerization can be used to modification of the chemical and physical properties of the polymeric materials and has attracted considerable interest because it imparts desirable properties such as blood compatibility. membrane quality, ion excahnge, dyeability, protein adsorption, and immobilization of bioactive materials. Synthesizing biocompatible materials by radiation method such as preirradiation or simultaneous irradiation has often used $\gamma$-rays to graft hydrophilic monomers onto hydrophobic polymer substrates. In this work, in attempt to produce surfaces that show low levels of anti-fouling of bovine serum albumin(BSA) solutions, hydroxyethyl methacrylate(HEMA) was grafted polypropylene membrane surfaces by preirradiation technique. The anti-fouling effect of the polypropylene membrane after grafting was examined by permeation BSA solution.

• 폴리머
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• 제33권5호
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• pp.477-484
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• 2009

소수성 실리카를 안정제로 AIBN을 개시제로 하는 현탁중합법으로 PBMA 입자 및 카본블랙을 함유하는 PBMA 복합체 입자를 합성하였다. pH를 이용하여 실리카입자를 표면개질하여 안정제로 선택한 반응에서 사용한 실리카의 90%는 안정제로, 10%는 PBMA 입자의 내부에 위치하는 것으로 규명되었다. 반응속도와 입경은 안정제의 농도에 무관한 것으로 관찰되었으나, 수평균 및 중량평균분자량은 안정제의 농도가 1.67 wt%를 초과하면서 증가하는 현상을 나타내었다. 개시제의 농도 증가와 반응온도의 상승에 따라 분자량은 이론식에 거의 일치하는 형태로 감소하였다. 카본블랙을 단량체에 대하여 1, 3, 5 및 7 wt% 유입하는 경우 반응전환율은 단계적으로 감소하였으며 유리전이온도는 카본블랙의 농도가 단량체에 대하여 3 wt%에서 5 wt%로 증가하는 경우 약 $4^{\circ}C$ 상승하였다. 투과전자현미경(TEM)을 이용하여 입자의 내부에 위치하는 카본블랙을 확인하였으며, 열중량분석법(TGA)으로 카본블랙의 농도를 측정하였다.

• 한국물환경학회지
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• 제38권3호
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• pp.143-149
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• 2022

Membrane distillation (MD) has emerged as a sustainable desalination technology to solve the water and energy problems faced by the modern society. In particular, the surface wetting properties of the membrane have been recognized as a key parameter to determine the performance of the MD system. In this study, a novel surface modification technique was developed to induce a Janus-type hydrophilic/hydrophobic layer on the membrane surface. The hydrophilic layer was created on a porous PVDF membrane by vapor phase polymerization of the pyrrole monomer, forming a thin coating of polypyrrole on the membrane walls. A rigid polymeric coating layer was created without compromising the membrane porosity. The hydrophilic coating was then followed by the in-situ growth of siloxane nanoparticles, where the condensation of organosilane provided quick loading of hydrophobic layers on the membrane surface. The composite layers of dual coatings allowed systematic control of the surface wettability of porous membranes. By the virtue of the photothermal property of the hydrophilic polypyrrole layer, the desalination performance of the coated membrane was tested in a solar MD system. The wetting properties of the dual-layer were further evaluated in a direct-contact MD module, exploring the potential of the Janus membrane structure for effective and low-energy desalination.

• 폴리머
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• 제25권5호
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• pp.754-758
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• 2001

Vesicle을 단량체가 중합 반응을 할 수 있는 장소로 사용하기 위하여, vesicle 내의 소수성부분에 단량체와 가교제를 집어넣었다. 즉 dimethyldioctadecylammonium bromide를 증류수 속에서 초음파 분산을 하여 vesicle을 만든 후, 여기에 styrene과 divinylbenzene을 첨가한 다음 AIBN으로 중합시켰다. 형성된 고분자는 남겨두고 vesicle을 형성하였던 계면활성제들을 모두 에탄올로 추출해서 제거하여 순수 고분자로 이루어진 구형의 구조물을 얻었다. 그리고 methyl methacrylate와 ethylene glycol dimethacrylate를 이용해서도 고분자로 이루어진 구형의 구조물을 합성하였다.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.26-26
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• 2012

The hydrophobic nature of the wool surface give rise to difficult penetration of dye molecules. Among all the methods of modification, graft polymerization is an attractive method to impart a variety of functional groups to a polymer. Grafting has been made by irradiating the light on the polymer in the presence of a solvent containing monomer. The energy source commonly used are high-energy electrons, X-rays, UV and visible light. UV irradiation is a relatively low-energy radiation in comparison with others since it has the least possibility to change bulk properties. In the present paper, a photo-reactive dye was synthesized from quinizarin by the reaction with methacryloyl chloride. The synthesized dye was continuously grafted onto wool fabric at room temperature by UV irradiation. Several key parameters including UV energy, dye concentration and pH have been examined to understand their influence on the photoreactive coloration.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.916-920
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• 2002

This report describes a high-level expression of human alpha-2a interferon ($IFN{\alpha}-2a$) in Escherichia coli and its pilot scale purification by using a monoclonal antibody-independent chromatographic procedure that is based on anion-exchange, cation-exchange, hydrophobic interaction, and gel filtration. The recombinant E. coli produced much more $IFN{\alpha}-2a$ in a soluble form, when cultivated at low temperatures than at high-temperature fermentation. However, if the bacterial growth was taken into consideration, fermentation at $30^{\circ}C$ seemed optimal for the interferon production. By using our new protocol, we recovered approximately 160 mg of $IFN{\alpha}-2a$ with a specific activity of $3.59{\times}10^8$ IU/mg from 201 of the broth. The gel permeation chromatographic and SDS-PAGE indicated that the interferon preparation was purified to homogeneity and was of the correctly folded fast-migrating monomer.

• 한국환경과학회지
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• 제29권8호
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• pp.801-808
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• 2020

In this study, an effective fluorescence pH sensor based on conjugated polyelectrolyte micelles (CPMs) was devised for detecting extremely acidic conditions. An amphiphilic coumarin derivative (CC12-N), a building block, was prepared, into which an ionizable amino group, aryl amine, was incorporated as a potential hydrophilic moiety. This monomer displays self-assembled micelle formation in extremely acidic pH ranges, giving a hydrophobic π-extended conjugated system at the inner part and hydrophilic functionality at the periphery, resulting in efficient fluorescence intensity enhancement. This new micelle-based fluorescence provides an efficient sensing platform for detecting very low pH values in the presence of competing substances.

• 약학회지
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• 제33권6호
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• pp.372-376
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• 1989

Equilibrium swelling and pH-sensitivity of a polyelectrolyte copolymer hydrogel were controlled by employing copolymers with different hydrophilic-hydrophobic balances. Model pH-sensitive hydrogels, e.g., poly(methacrylic acid), poly(methacrylic acid-co-acrylamide), poly(methacrylic acid-co-2-hydroxyethylmethacrylate), poly(methacrylic acid-co-styrene) were synthesized at various monomer compositions. As hydrophobicity of the copolymer hydrogels increased, the equilibrium swelling decreased while the pH-sensitivity increased. In the case of poly(methacrylic acid-co-acrylamide), polymer-polymer interaction significantly affected the equilibrium swelling and provided a wide range control of pH-sensitivity.

• Bulletin of the Korean Chemical Society
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• 제7권2호
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• pp.113-116
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• 1986

Spectral behaviors of cationic dyes, methylene blue(MB) and acridine orange(AO), with varying concentrations of sodium dodecylsulfate(SDS) were studied. At low concentration of SDS(<1mM), these dyes formed insoluble dye-surfactant aggregates. When [SDS] is 4-5 mM, the aggregates were dissolved into mixed micelles of constant composition. At higher concentration of [SDS], the composition of mixed micelles were changed with [SDS], resulting only monomeric form of dyes in micelles. AO-SDS system showed greater aggregating and less dissolving properties, and weaker effect of salt than MB-SDS system did. These were attributed to the greater hydrophobic nature of the former dye. The monomer/dimer ratios of dyes in mixed micelles at given [SDS] were greatest at $20^{\circ}C$, reflecting the dependency of CMC of the surfactant on temperature.