• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.232-233
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• 2006

In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.

• 멤브레인
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• 제11권3호
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• pp.124-132
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• 2001

고온에서 수소 분리 회수를 목적으로 silica/alumina 복합 막을 합성하였다. 막의 선택 투과 성능을 향상시키기 위해, sol-gel법에 의한 silica 및 alumina층을 중간층으로 도입하고, 그 위에 강제유동 CVD법에 의한 silica를 합성하였다. Sol-gel법에 의해 ${\alpha}$-alumina tube에 합성한 ${\gamma}$-alumina 및 silica 막은 Knudsen 확산 영역의 많은 mesopore를 포함하고 있어서 수소 선택 분리 막으로는 적합하지 못했다. 하지만, sol-gel법에 의해 합성한 silica/${\gamma}$-alumina층에 강제유동 CVD법으로 silica를 합성한 결과, 질소 투과 영역의 세공이 완전히 제거되어, 높은 수소 선택성을 가지는 복합 막이 형성되었다. 그 막은 온도에 따라 수소 투과 속도가 증가하여 $450^{\circ}C$에서 $5.57{\times}10^{-8}molm^2s^LPa^1$의 수소 투과 속도와, 9.52 kJ/mol의 활성화 에너지를 나타냈다. 분자체 효과에 의해 질소 투과가 완전히 배제되고, 수소만 선택적으로 투과되는 silica/alumina 복합막이 성공적으로 합성된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권4호
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• pp.277-281
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• 2006

Spherical micro silica sol-gel immobilized enzyme beads were prepared in an emulsion system using cyclohexanone and Triton-X 114. The beads were used for the in situ immobilization of transaminase, trypsin, and lipase. Immobilization during the sol to gel phase transition was investigated to determine the effect of the emulsifying solvents, surfactants, and mixing process on the formation of spherical micro sol-gel enzyme beads and their catalytic activity. The different combinations of sol-gel precursors affected both activity and the stability of the enzymes, which suggests that each enzyme has a unique preference for the silica gel matrix dependent upon the characteristics of the precursors. The resulting enzyme-entrapped micronsized beads were characterized and utilized for several enzyme reaction cycles. These results indicated improved stability compared to the conventional crushed form silica sol-gel immobilized enzyme systems.

• 한국세라믹학회지
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• 제29권5호
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• pp.357-366
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• 1992

Residual organics were considered as impurity in Sol-Gel method. The purpose of this study was to find the conditions to contain as much residual organics as possible in silica gel prepared from TEOS(tetraethylortho-silicate) by Sol-Gel method. Residual organics are to be expected to have reduction effect on synthesizing Si3N4 from silica gel. The results of this study are follows: 1) The maximum content of entrapped carbon was 19.8 wt.%(C/SiO2=0.25 wt.ratio) in silica gel synthesized under the conditions 1.5 fold mole water for incomplete hydrolysis, 2.5 fold mole phenol as a solvent and 0.1 fold mole HCl as a catalyst to TEOS. 2) Silica gel with organics entrapped by Sol-Gel method had a positive effect on the formation of Si3N4 compared with commercial silica gel. 3) Sintered body of synthesized $\alpha$-Si3N4 with Y2O3 and Al2O3 as additives at 175$0^{\circ}C$ in N2 atmosphere showed bending strength, 602$\pm$20 MPa and frature toughness 4.45$\pm$0.15 MPa.m1/2.

• 한국세라믹학회지
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• 제26권5호
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• pp.677-681
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• 1989

On the preparation of silica glass by sol-gel process, we used fine powder of silica gel to prevent cracking. In this case, the best condition of silica glass preparation is the contents of 10~40wt% seed and the gelation time of solution in contract. The dried gels conversed to silica glass by heat treatment up to 125$0^{\circ}C$.

• 한국분말재료학회지
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• 제23권6호
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• pp.442-446
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• 2016

The sol-gel method is the simplest method for synthesizing monodispersed silica particles. The purpose of this study is to synthesize uniform, monodisperse spherical silica nanoparticles using tetraethylorthosilicate (TEOS) as the silica precursor, ethanol, and deionized water in the presence of ammonia as a catalyst. The reaction time and temperature and the concentration of the reactants are controlled to investigate the effect of the reaction parameters on the size of the synthesized particles. The size and morphology of the obtained silica particles are investigated using transmission electron microscopy and particle size analysis. The results show that monodispersed silica particles over a size range of 54-504 nm are successfully synthesized by the sol-gel method without using any additional process. The nanosized silica particles can be synthesized at higher TEOS/$H_2O$ ratios, lower ammonia concentrations, and especially, higher reaction temperatures.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.967-972
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• 2004

Hardness and surface property of coated gel materials are considerably different according to kinds(particle size/stabilized ion) of colloidal silica(CS), kinds of silanes, content ratio of silane versus CS, and reaction degree in sol solution. We report the properties of sol-gel coating materials in which the factors of reaction are kinds of CS, contents ratio of CS and MTMS, and reaction time of sol. The contact angles of the coated films obtained from the mixed CS system showed a little good relationship with MTMS content increase to those from HSA CS reaction system and the change of contact angle didn't have much effect on reaction time of sol. In the coating films obtained from HSA CS reaction system, the surface was much rough in case of that the content MTMS decreased and the reaction of sol kept long. The surface roughness of films obtained from the mixed CS reaction system showed similar tendency, though its degree was a little different. In synthesis of sol-gel coating materials, we could identify that choice of CS kinds and content ratio of CS and silane were important and it was desirable the reaction time of sol is not long.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.230-231
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• 2006

We synthesized sol according to kinds(particle size/stabilized ion) of colloidal silica(CS), content ratio of alkoxysilane versus CS and reaction degree in sol solution and studied the surface property of coated gel materials. The contact angle of the thin films prepared from LHSA/N1030 CS/tetramethoxysilane(TMOS)/methyltrimethoxysilane(MTMS) sol-gel reaction system showed a little good relationship with content ratio of TMOS/MTMS silanes. The surface roughness of LHSA CS/TMOS/MTMS reaction system showed flatter than that of LHSA/N1030 CS. The thermal degradation of LHSA CS/TMOS/MTMS coating flim occurred at $550^{\circ}C$.

• 한국환경과학회지
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• 제12권4호
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• pp.481-485
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• 2003

Two types of polyimide/silica composite films were prepared using sol-gel method through hydrolysis and polycondensation of tetraethoxysilane (TEOS) with the polyamic acid (PAA) and end-capped PAA solution. Samples were characterized by the means of differential thermogravimetry, X-ray diffractometry, scanning electron microscopy, universal test, impedance analyzer, chemical resistance test, etc. All of the PAA/silanol solutions heat-treated at 300$^{\circ}C$ for 6h were transformed to polyimide/silica composites. It has been demonstrated that the properties of polyimide/silica composites were affected by the amount of silica addition and the bend type existed between polyimide and silica.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.535-540
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• 2011

금속염인 lanthanum nitrate를 증류수에 용해시킨 후 실란커플링제인 ${\gamma}$-glycidyloxypropyl trimethoxysilane과 금속산화물인 colloidal silica를 이 용액에 첨가하여 sol-gel법에 의해 유-무기 혼성 용액을 제조하였다. 또한 spiropyran계 광변색 염료를 용매인 tetrahydrofuran에 용해시킨 후 앞서 제조한 혼성 용액과 혼합하여 광 변색 코팅 용액을 제조하였다. 그 후 기재인 polycarbonate 시트에 코팅시키고 열 경화시켜 광 변색성을 갖는 하드 코팅 막을 제조하였다. 이 과정 중 colloidal silica의 첨가량이 코팅 막의 광변색 특성에 미치는 영향을 조사하였다. Colloidal silica의 첨가량이 증가할수록 코팅 막의 소색속도가 빨라졌으며 연필경도가 증가하였다.