• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.271-271
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• 2006

The present article describes a novel method of preparing the sulfonated polysulfone-based PEMs for DMFC, which are excellent in film quality, proton conductivity, methanol impermeability and mechanical properties. No depression in film quality or difficulty in film preparation is observed, even though sulfonated group of the PEMs are kept as high as 70 mol %. Allyl-terminated cooligo-PESs containing the organic sulfonate groups were solvent-cast into films and then thermally treated for cross-linking. Cross-linked sulfonated polysulfone-based PEMs gave unprecedented reduction of methanol cross-over and high ionic conductivity through in-situ thermal polymerization and cross-linking of telechelic sulfonated sulfone oligomers during a membrane preparation.

• Journal of Pharmaceutical Investigation
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• 제41권5호
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• pp.279-288
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• 2011

The Dexamethasone (DEX) loaded chitosan microspheres were prepared by thermal denaturation and chemical cross-linking method using a dierent concentration of glutaraldehyde as chemical cross-linking agent. The prepared microspheres were evaluated for the percentage of Drug Loading (DL), Encapsulation Efficiency (EE) and surface morphology by Scanning Electron Microscopy (SEM). DL and EE were found to be maximum range of 10.0 to 10.79 % and 58.19 to 64.73 % respectively. The SEM Photographs of the resultant microspheres exhibited fairly smooth surfaces and predominantly spherical in appearance. In addition, Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) shown that there was no interaction between the drug and polymer. In vitro and in vivo release studies revealed that the release of dexamethasone was sustained and extended up to 63 days and effectively controlled by the extent of cross-linking agent. Non-clinical parameters such as paw volume, hematological parameters like Erythrocyte Sedimentation Rate (ESR), Paced Cell Volume (PCV), Total Leucocytes Count (TLC), Hemoglobin (Hb), Differential Cell Count (DCC) were investigated in Fruend's Complete Adjuvant (FCA) induced arthritic rats. Radiology and histopathological studies were also performed in order to evaluate the therapeutic efficacy of the DEX-loaded microspheres in extenuating the rat arthritic model.

• 한국고분자학회지:고분자과학과기술
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• 제8권3호
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• pp.298-305
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• 1997

• 공업화학
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• 제30권6호
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• pp.643-651
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• 2019

Polybenzimidazole (PBI), an engineering polymer with well-known excellent thermal, chemical and mechanical stabilities has been recognized as an alternative to high temperature polymer electrolyte membranes (HT-PEMs). This review focuses on recent advances made on the development of PBI-based HT-PEMs for fuel cell applications. PBI-based membranes discussed were prepared by various strategies such as structural modification, cross-linking, blending and organic-inorganic composites. In addition, intriguing properties of the PBI-based membranes as well as their fuel cell performances were highligted.

• Macromolecular Research
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• 제16권3호
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• pp.189-193
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• 2008

Thermal cross-linking method of poly(vinyl alcohol) (PVA) using poly(acrylic acid) (PAA) was carried out on PVA/PAA hydrogels. The level of gelation was measured in the PVA/PAA hydrogels with various PAA contents. The swelling behavior at various pHs showed that the swelling kinetics and water contents of the PVA/PAA hydrogels reached equilibrium after 30 h, and the time to reach the equilibrium state decreased with increasing PAA content in the hydrogel. The water content increased with increasing pH of the buffer solution. The permeation and release of the drug were tested using indomethacin as a model drug. The permeated and released amounts of the drug increased with decreasing the PAA content because of the low free volume in the hydrogel due to the higher cross-linking density. The kinetic profile of drug release at various pHs showed that all samples reached the equilibrium state within the 5 h.

• Macromolecular Research
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• 제17권7호
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• pp.522-527
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• 2009

A photocrosslinkable polyphosphazene was used for molecular imprinting. We synthesized polyphosphazene (3) having urea groups for complexation with N-carbobenzyloxyglycin (Z-Gly-OH, template) and chalcone groups for cross-linking reaction. As substituents, 4-hydroxycha1cone (1) and N-(4-hydroxyphenyl)-N'-ethylurea (2) were prepared. Choloro groups of poly(dichlorophosphazene) were replaced by the sequential treatment with sodium salts of compounds 1 and 2, and trifluoroethanol. The template molecule was complexed with the urea groups on the polymer chains via hydrogen bonding. A thin polymer film was prepared by casting a solution of the complex of polymer 3 and the template in dimethylformamide on a quartz cell and irradiated with 365 nm UV light to yield a cross-linked film with a thickness of about $16{\mu}m$. The template molecules in the film were removed by Soxhlet extraction with methanol/acetic acid. The control polymer film was prepared in the same manner for the preparation of the imprinted polymer film, except that the template and triethylamine were omitted. In the rebinding test, the imprinted film exhibited much higher recognition ability for the template than the control polymer. We also investigated the specific recognition ability of the imprinted polymer for the template and its structural analogues. The rebinding tests were conducted using Z-Glu-OH, Z-Asp($O^tBu$)-OH, and Z-Glu-OMe. The imprinted film showed higher specific recognition ability for the template and the lowest response for Z-Asp($O^tBu$)-OH.

• 한국응용과학기술학회지
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• 제32권4호
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• pp.718-723
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• 2015

For the fabrication of the Si negative electrode in Li-ion batteries (LIBs) containing the cross-linking polymer binder, in this work, the urethane acrylate (UA) oligomer was synthesized via a simple synthetic process. The cross-linked poly(urethane acrylate) (CPUA)/carbone black (CB)/Si composite (CPUA/CB/Si composite) was fabricated through reactions between their reactive vinyl segments in the UA oligomer. Interestingly, the CPUA/CB/Si composite showed better cycle performance than the poly(vinylidene fluoride) (PVdF)/CB/Si composite (PVdF/CB/Si composite) and the polyurethane (PU)/CB/Si composite (PU/CB/Si composite). The CPUA/CB/Si composite had the best lithiation of about $2586mAh\;g^{-1}$. The UA oligomer showed a good compatibility with the electrode materials and current collector after and before a curing process.

• 폴리머
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• 제24권3호
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• pp.418-430
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• 2000

알칼리키토산과 프로필렌옥사이드를 반응시킴에 의해 유방성 및 열방성 액정상을 형성하는 새로운 히드록시프로필키토산(HPCTO)을 합성함과 동시에 HPCTO/메탄올의 유방성 액정용액에 glyoxal첨가하여 주형시킴에 의해 HPCTO의 가교필름들을 제조하였다. 가교필름들의 열 및 팽윤 특성을 검토하였다. 필름들은 cholesteric 액정상의 특징적인 지문조직을 나타내었으며 이들의 pitch는 온도 및 가교제의 농도가 증가할수록 증가하였다. 가교시료들은 물과 메탄을 중에서 이방성 팽윤을 나타내었으며, 이러한 사실은 HPCTO분자들간에 2차원적인 가교가 우선적으로 일어남을 시사한다. 이방성 팽윤의 정도는 용매의 종류에 크게 의존하나 검토된 가교제의 농도에는 의존하지 않았다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.168-168
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• 2006

Low-operating voltage organic field-effect transistors (OFETs) have been realized with high dielectric constant (${\kappa}$) polymer such as cyanoethylated poly vinyl alcohol (CR-V, ${\kappa}=12$). Since the $high-{\kappa}$polymers are likely to contain water and ionic impurities, large hysteresis and considerable leakage current are frequently observed in OFETs. To solve these problems, we cross-linked the CR-V by using a cross-linking agent. Cross-linked CR-V dielectrics showed high dielectric constant of 11.1 and good insulating properties, resulting in a high capacitance ($81nF/cm^{2}$ at 1MHz) at 120 nm of dielectric thickness. Pentacene FETs with cross-linked CR-V dielectrics exhibited high carrier mobility ($0.72\;cm^{2}/Vs$), small subthreshold swing (185 mV/dec) and little hysteresis at low-operating voltage (${\Leq}-3V$).

• Journal of Pharmaceutical Investigation
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• 제36권2호
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• pp.83-87
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• 2006

Poly(acrylic acid) (PAA) was identified to possess good mucoadhesive properties ensuring its application to extend the retention times of the formulations at the oral cavity, intended route of administration using the polymer. In the noncross-linked state, PAA will swell and become eroded owing to the presence of salivary flow from the site of application. The formation of cross-links between the polymer chains will allow swelling but prevents the erosion of the dosage form. In the current study, cross-linking was achieved by esterification of the PAA chains with sucrose. The density of crosslinking was modified by changing sucrose concentration and the duration of cure time. The cross-linking density of the polymer hydrogel was assessed by equilibrium swelling studies. The mucoadhesion testing method allowed a comparative study of the hydrogels prepared. An inverse relationship between equilibrium swelling and peak detachment force showed that increased PAA chain density per unit area enhanced the mucoadhesive interaction.