• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.237.1-237.1
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• 2003

Cefuroxime axetil, a broad spectrum antibiotic, has been known to form a gelatinous mass in contact with aqueous media, which could lead to poor dissolution. Therefore, this study was conducted for removing the gelling phenomenon and thereby obtaining a favorable dissolution profile. We have found that the addition of poly (methacrylic acid, methyl methacrylate) could not only inhibit the tendency of cefuroxime axetil to form a gel but also showed the good dissolution profile compared to the formula without poly (methacrylic acid, methyl methacrylate). (omitted)

• 폴리머
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• 제33권3호
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• pp.230-236
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• 2009

비닐 아세테이트/알킬메타크릴레이트계 에멀젼 공중합에서 반응온도, 개시제의 종류와 농도, 보호콜로이드인 PVA의 종류와 농도, 공단량체인 MMA, EMA의 조성비를 변화시키며 중합하였다. 제조된 공중합체인 poly(vinyl acetate-co-methyl methacrylate)(PVAc/PMMA), poly(vinyl acetate-co-ethyl methacrylate)(PVAc/PEMA)를 수분 측정기를 사용하여 100, 130, 150, 180, $200^{\circ}C$에서 등온건조 시키고, 그 건조 특성을 고찰하여 다음과 같은 결론을 얻었다. 등온법으로 얻은 중합체 고형화 과정의 활성화 에너지는 PVAc/PMMA> PVAc/PEMA> PVAc의 순으로 공단량체의 곁사슬의 탄소수 증가에 따라 감소하였다. 접착박리강도는 동일한 조성의 공중합체에서 보호콜로이드 함량에 비례하여 증가하였고, 내수 접착박리강도는 최적의 보호콜로이드 함량에서 공단량체의 종류와 함량에 따라 PVAc/PMMA>PVAc/PEMA>PVAc 순이다.

• Macromolecular Research
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• 제11권6호
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• pp.418-424
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• 2003

Exfoliated poly(methyl methacrylate-co-styrene) [P(MMA-co-ST)]/silicate nanocomposites were synthesized through a multistep emulsion polymerization. The methyl methacrylate monomers were polymerized first and then the styrene monomers were polymerized. The nanocomposites had core-shell structures consisting of PMMA (core) and PS (shell); these structures were confirmed by $^1$H NMR spectroscopy and TEM, respectively. P(MMA-co-ST) copolymers showed two molecular weight profiles and two glass transition temperatures (T$_{g}$) in GPC and DMA measurements. At 30 $^{\circ}C$, the nanocomposites exhibited 83 and 91 % increases in their storage moduli relative to the neat copolymer because the silicate layers were dispersed uniformly in the polymer matrix.x.

• Macromolecular Research
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• 제13권2호
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• pp.102-106
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• 2005

Poly(methyl methacrylate) (PMMA)/sodium montmorillonite (Na-MMT) nanocomposites were prepared with a novel method utilizing a macroazoinitiator (MAI). To induce the intergallery polymerization of methyl methacrylate (MMA), the MAI containing a po1y(ethylene glycol) (PEG) segment was intercalated between the lamellae of Na-MMT and swelled with water to enhance the diffusion of MMA into the gallery. The structure of the nanocomposite was examined using X-ray diffraction and transmission electron microscopy, and the thermal properties were examined using differential scanning calorimetry and thermogravimetry. The PMMA/Na-MMT nanocomposite prepared by intergallery polymerization showed a distinct enhancement of its thermal properties; an approximately $30^{\circ}C$ increase in its glass transition temperature and an $80\sim100^{\circ}C$ increase in its thermal decomposition temperature for a $10\%$ weight loss.

• 폴리머
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• 제25권6호
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• pp.848-854
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• 2001

무정형 고분자인 ethylene-methyl acrlate-glycidyl methacrylate 공중합체 (E-MeA-GMA)와 결정성 고분자인 poly(ethylene terephthalate) (PET)와의 블렌드에서 그라프트 반응에 따른 PET의 결정화 거동을 조사하였다. PET와 E-MeA-GMA간의 그라프트 반응 수준을 torque-rheometer, FT-IR, SEM을 이용하여 확인하였으며, 반응시간에 따른 결정화 거동 변화를 DSC와 광산란 방법을 이용하여 관찰하였다. 또한 라멜라 수준의 결정구조를 소각 X선 산란법을 이용하여 조사하였다.

• Fibers and Polymers
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• 제6권4호
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• pp.277-283
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• 2005

In order to prepare high molecular weight poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres, methyl methacrylate was suspension-polymerized in the presence of silver nanoparticles at low temperature with 2,2'-azobis(2,4-dimethylvaleronitrile) as an initiator. The rate of conversion was increased by increasing the initiator concentration. When silver nanoparticles were added, the rate of polymerization decreased slightly. High monomer conversion (about $85\%$) was obtained in spite of low polymerization temperature of $30^{\circ}C$. Under controlled conditions, PMMA/silver microspheres with various number-average degrees of polymerization (6,000-37,000) were prepared. Morphology studies revealed that except for normal suspension microspheres with a smooth surface, a golf ball-like appearance of the microspheres was observed, due to the migration and aggregation of the hydrophilic silver nanoparticles at the sublayer beneath the microsphere's surface.

• Macromolecular Research
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• 제8권6호
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• pp.292-297
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• 2000

The theoretical synthesis of the isotactic and syndiotactic poly(methyl methacrylate) were carried out as a model for real polymerization reactions following the normal chain reaction processes by repeating the uniform localization of wave functions with inclusion of the interaction between the end group of the cluster and an attaching molecule by the elongation method, and then, the calculated value was compared with the usual PM$_3$ calculation. The results revealed that a reaction of cluster with monomer molecules has made it possible to calculate the electronic structure and total energy of polymer with nearly infinite length and a matrix of constant dimension. The isotactic poly(methyl methacrylate) is more stable than syndiotactic one. The same tendency have been found between the experimentally measured properties and a calculated total energy to explain the chain motion in isotatic and syndiotactic poly(methyl methacrylate).

• 한국응용과학기술학회지
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• 제4권1호
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• pp.67-71
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• 1987

The transesterification reaction between diethanolamine and methyl methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $120^{\circ}C$. The amount of reacted methyl methacrylate was measured by gas chromatography and liquid chromatography, and the reaction rate also measured from the amount of reaction products and reactants under each catalyst. The transesterification reaction was carried out in the first order with respect to the concentration of diethanolamine and methyl methacrylate, respectively. The over-all order is 2nd. The apparent rate constant was found to obey first-order kinetics with respect to the concentration of catalyst. The maximum reaction rate was appeared at the range of 1.4 to 1.6 of electronegativity of metal ions and instability constant of metal acetates.

• 공업화학
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• 제17권4호
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• pp.426-431
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• 2006

Poly(methyl methacrylate) (PMMA)의 착색을 위하여 아크릴 그리고 비닐설폰기를 가지는 청색 및 오렌지 아조 염료들을 6-bromo-2-cyano-4-nitroaniline과 2,5-dimethoxy-4-(vinylsulfonyl)benzenamine을 3-acrylamido-(N,N-diethylamino) benzene과 3-methyl-(N,N-diethylamino)benzene의 아조 짝지음 반응을 이용하여 각각 합성하였다. 또한 알릴기를 가지는 염료는 비닐설폰과 allylamine과의 반응에 의하여 제조하였다. PMMA의 착색은 아크릴, 비닐설폰 그리고 알릴 작용기를 가지는 염료를 직접 methyl methacrylate (MMA)와 공중합하거나, MMA와 공중합한 고분자염료 및 반응성기가 없는 염료 2를 직접 MMA에 용해하여 중합과 동시에 착색하였다. 3가지로 착색한 PMMA의 염색 견뢰도를 여러 환경 조건에서 염료의 용해도를 비교하여 평가하였다.

• 한국안전학회지
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• 제16권3호
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• pp.68-75
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• 2001

Photopolymerization, the utilization of electromagnetic radiation(or light) as the energy source for polymerization of functional monomers, oligomers is the basis of important commercial processes with broad applicability, including photoimaging and RV curing of coatings and inks. The objective of this study is to investigate the characteristics of environmental fraternitive photopolymerization of methyl methacrylate(MMA). This work is the first step to continue further research about alkyl methacrylate. The experiment was done in aqueous solution under the influence of photo-initiator concentration(0.05-0.25mol/l), light intensity (5000-9000 ${\mu}J/cm^2$) and monomer concentration(2-6mol/l). Methyl methacrylate was polymerized to high conversion ratio using hydrogen peroxide($H_2O_2$) and the kinetics model we have obtained is as follows. $R_p=k_p[S]^{0.41}[M]^{0.62}[L]^{2.45} exp(53.64/RT$). The differential method of thermogravimetric analysis(Friedman method) was used to obtain value of activation energy on decomposition reaction. The average value of it res 45.4Kca1/mol.