• Korea-Australia Rheology Journal
• /
• 제21권3호
• /
• pp.185-191
• /
• 2009

Polystyrene/multi-walled carbon nanotube (PS/MWCNT) composites were prepared by the use of latex technology. The monodisperse PS latex was synthesized by an emulsifier-free emulsion polymerization from styrene/potassium persulfate/water system in the presence of ethanol. The MWCNTs were first treated with acid mixture to eliminate impurities, dispersed in deionized water driven by ultrasonicator, and then mixed with the PS latex. From these mixtures, PS/MWCNT composites were prepared by freeze-drying and subsequent compression molding. In the small-amplitude oscillatory shear experiments, both complex viscosity and storage modulus increased with increasing MWCNT content. A pronounced effect of MWCNT content was observed, resulting in larger storage modulus and stronger yield behavior at low frequencies when compared to unmodified PS. It showed a transition from viscous to elastic behavior with increasing MWCNT content. Over the MWCNT content of 3 wt%, the storage modulus was higher than the loss modulus across all frequencies.

• 한국응용약물학회:학술대회논문집
• /
• 한국응용약물학회 1993년도 제2회 신약개발 연구발표회 초록집
• /
• pp.145-145
• /
• 1993

일반적으로 단백질의 정제를 위한 가장 효과적인 방법은 affinity chromatography법으로 알려져 있다. 본 연구에서는 베타 수용체의 순수정제를 위한 효과적인 affinity matrix를 제조하고 이의 특징을 확인함으로써 수용체 정제를 위한 기초를 수립하고자 하였다. Bisoxirane reagent인 1,4-butanediol diglycydyl ether를 Sepharose CL-4B gel과 반응시켜 탄노원자 10개 길이의 spacer arm을 부착시켰다. 여기에 sodium persulfate, dithiothreitol을 연속적으로 사용하여 -SH기를 도입시긴 추 free radical 반응을 이용하여 베타수용체 길항제인 alprenolol을 부착시킴으로써 affinity gel을 제조하였다. alprenolol치 부착반응을 위한 최적온도는 4$0^{\circ}C$로 나타났으며, semimicro Kjeldahl 질소 분석법을 적용하여 gel을 분석한 결과 ml당 0.4-0.6 $\mu$ mol의 alprenolol이 결합하였음을 확인하였다.

• Macromolecular Research
• /
• 제10권3호
• /
• pp.140-144
• /
• 2002

Dispersion polymerization of acrylamide was carried out in the media of methyl alcohol/$H_2O$ mixtures using hydroxypropyl cellulose and ammonium persulfate as steric stabilizer and initiator, respectively. The effects of concentrations of initiator and steric stabilizer, amount of monomer, polymerization temperature, methyl alcohol/$H_2O$ ratio, and purification of monomer and nitrogen purge on the particle size of the latices and molecular weight of the polymers were investigated. The average particle diameter increased with increasing concentration of initiator, water content in methyl alcohol/$H_2O$ media, and polymerization temperature, but decreased with monomer and stabilizer concentrations. The viscosity average molecular weight increased with increasing concentrations of monomer, steric stabilizer, and water content in dispersion media, but decreased with initiator concentration and polymerization temperature. The PAM polymers prepared with the purified monomer and the nitrogen purging before the reaction showed the highest molecular weight.

• Bulletin of the Korean Chemical Society
• /
• 제27권2호
• /
• pp.251-254
• /
• 2006

The formation of polyaniline (PANI) in the reverse micelles of poly(oxyethylene) nonylphenyl ether, $(NP5, H(CH_2)_9Ph(OC_2H_4)_5OH)$, was investigated by small-angle neutron scattering (SANS). The reverse micellar solution containing initiators in the inner part of reverse micelle was prepared with surfactant (NP5), water, cyclohexane and an initiator (ammonium persulfate (APS)). The core-shell sphere model containing smearing effect reveals that the polymerization occurs on the shell layer of the reverse micelles. Shell thickness averages varied from 48 $\AA$ to 109 $\AA$ with increases of monomer concentration.

• 한국응용과학기술학회지
• /
• 제6권1호
• /
• pp.21-26
• /
• 1989

Four fatty acid vinyl esters were synthesized by transesterification between vinyl acetate and lauric acid, myristic acid, palmitic acid, stearic acid, respectively. Fatty acid vinyl ester oligomers were prepared from polymerization of four fatty acid vinyl esters in the presence of potassium persulfate in methanol. The ${\alpha}-sulfonation$ of these four fatty acid vinyl ester oligomer were carried by direct addition of sulfur trioxide. Especially, molecular weights of sodium ${\alpha}-sulfo$ fatty acid vinyl ester oligomers were measured by boiling point method.

• 한국응용과학기술학회지
• /
• 제25권1호
• /
• pp.83-90
• /
• 2008

The core-shell latex particles were prepared by sequential emulsion polymerization using alkyl methacrylate as a shell monomer and potassium persulfate (KPS) as an initiator. We study the effects of core-shell structure of calcium carbonate/alkyl methacrlyate in the presence of an anionic surfactant sodium lauryl sulfate (SLS) and polyoxyethylene alkyl ether sulfate (EU-S133D)). The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by transmission electron microscope (TEM).

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.1573-1574
• /
• 2009

Fullerene/polystyrene nanoparticles having the average size of 300 nm ~ 1 ${\mu}m$ were prepared by emulsion polymerization in aqueous medium. Poly(vinyl pyrrolidone) and potassium persulfate were used as a dispersant and an initiator, respectively. The contents of fullerene in the nanoparticle were controlled to be from 10 to 57 wt% by varying the feed ratio, which was confirmed by IR-spectroscopy, thermogravimetric analyses, and elemental analyses. Dynamic light scattering experiments revealed the particles have a broad size distribution. Further characterizations of the nanoparticles were performed by using SEM and TEM observation. The high content of fullerene in the particles will find applications in photovoltaic and organic semiconducting area.

• 한국안전학회지
• /
• 제17권4호
• /
• pp.133-139
• /
• 2002

Core-shell polymers of inorganic/organic pair, which are consisted of both core and shell component, were synthesized by sequential emulsion polymerization using ethyl methacrylate (EMA) as a shell monomer and ammonium persulfate as initiator. We found that $CaCO_3$ core should be prepared by adding 2.0wt% SDBS(sodium dodecyl benzene sulfonate), $CaCO_3$ core/PEMA shell polymerization was carried out on the surface of $CaCO_3$ particle during EMA shell polymerization in the core-shell polymer preparation. The structure of core-shell polymer were investigated by measuring the degree on decomposition of $CaCO_3$ by HCI solution, thermal decomposition of polymer composite on thermogravimetric analyzer, glass transition temperature on differential scanning calorimeter, and morphology using scanning electron microscope.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.109-110
• /
• 2007

Pyrrole and DNA can be used for synthesis of conducting nanowires. Protonated pyrrole and negatively charged DNA are absorbed by electrostatic interaction. The level of absorbance is related to pH of pyrrole. Therefore, DNA immobilized and aligned on the 3-aminopropyltrimethoxysi1ane (APTES) modified Si surface. Positive pyrrole monomers was deposited on aligned DNA for the synthesis of nanowire in various pH condition. And polypyrrole nanowires were synthesized by polimerization with ammonium persulfate (APS). These polypyrrole nanowires were measured by AFM, and then we found optimal pH level for the synthesis of nanowires.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.416-417
• /
• 2005

In this study, we optimized the process of Si anisotropy etching by combing tetramethyl ammonium hydroxide (TMAH) etching process with ultrasonic wave technology. New ultrasonic TMAH etching apparatus was developed and it was used for fabricating a $20{\mu}m$ thick diaphragm for Si piezoresistive pressure sensors. Based on comparison study on etch rate and surface flatness, it was observed that the Si anisotropy etching methode with new ultrasonic TMAH etching apparatus (at 40 kHz/ 500 watt) was superior to conventional etching methods with TMAH or TMAH+ammonium persulfate(AP) solutions.