• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.231-234
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• 2003

CS와 실란의 반응시 생성된 실란올들이 동종간의 반응에 비하여 실리카 표면과의 반응이 진행되는 효과에 따라서, 그리고 실란들의 종류에 따라 경화밀도와 재료특성이 상당히 달라지게 된다. 본 논문에서는 CS/MTMS 졸반응에서 CS의 종류, CS/MTMS의 함량비, 졸의 반응시간 등을 인자로 하여 졸들을 합성하고 겔화된 도막의 물성들을 조사하였다. 그 결과 MTMS의 함량과 비례하여 친수성은 증가하고 표면조도는 나아지는 것을 알 수 있었고 반응시간에 비례하여 친수성은 감소하고 표면조도는 안 좋아지는 것을 알 수 있었다. 그리고 내열성은 MTMS의 함량이 적을수록 좋은 결과를 나타내었다.

• Polymer(Korea)
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• v.31 no.2
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• pp.111-116
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• 2007

Polyurethane modified acrylate $(PUA)/SiO_2$ hybrid films were prepared by ultraviolet curing and their surface properties were investigated by hardness and adhesion test. The films were examined by the manipulation of mole-ratio of organic to inorganic components. Under the silica content controlled, highly desirable films were achieved and scratch resistance and hardness property of film were also enhanced, which indicates that the crosslinked silica particles are homogeneously dispersed within PUA film.

• The Korean Journal of Rheology
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• v.10 no.1
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• pp.24-30
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• 1998

솔젤법을 이용하여 단분산의 실리카 입자를 제조하고 농도변화에 따른 실리카 분산 액의 유변학적 거동을 해석하였다. 단분산 실리카 입자의 제조는 솔젤법을 이용한 액상반으 으로 제조하였고 입자의 안정화를 위하여 입자표면에 실란커플링제를 코팅하여 유기용매에 서 안정성을 갖도록 하였다. 분산액의 농도에 따른 유변학적 거동을 조사하기 위하여 부피 분율( )이 0.05인 희박 분산계로부터 =0.55의 고농도 분산계를 제조하였다. 솔젤법을 통하 여 단분산 실리카 입자를 성공적으로 제조하였으며 실란커플링제인 ${\gamma}$-methacryloxypropyl triethoxysilane로 입자의 표면을 화학적 방법으로 처리하여 유기용매 상에서 알킬기의 작용 에 의한 hard-sphere'특성을 나타내도록 하였으며 동시에 분산안정성을 유지할수 있었다. 입자 분산계는 =0.25이하의 부피농도에서는 분산용매와 같은 뉴톤거동을 보여주었으며 이 이이상의 농도에서는 비뉴톤거동인 전단담화(shear thinning)현상과 high shear limiting viscosity를 나타내었다. 이결과는 Krieger-Dougherty 식을 따름이 확인되었으며 부피분율 =0.50정도까지도 이식이 잘적용됨을 확인하였다. 부피분율 =0.50 이상의 고농도 입자 분산계 는 급격한 점도의 증가와 함께 전단담화와 전단탁화(shear thickening)현상이 모두 관찰되었 다. 특히 전단탁화를 일으키는 특헝전단변형률(cr)이하의 전단변형률에서는 안정되고 빠른 점성반응(viscous response)을 보여주었으나 특성 전단변형률 부근과 이상의 전단변형률 영 역에서는 매우 불안한 거동이 보여짐을 확인하였다. 그러나 이러한 점도 거동은 가역적이며 전단변형률을 증가시킬때와 감소시킬 때의 유변학적 거동이 거의 일치하였다.

• Korean Journal of Materials Research
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• v.20 no.5
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• pp.252-256
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• 2010

The study was done to change the morphology and pore size of SBA-15 silica, and the characteristics of SBA-15 silica were investigated with TG-DSC, XRD, SEM, TEM and N2 adsorption-desorption under changing aging conditions. SBA-15 silica having a 2D-hexagonal structure was synthesized and confirmed by SEM and TEM. The structure of mesoporus silica SBA-15 showed a pore having regularly formed hexagonal structure and a passage having a cylindrical shape. This result is in good agreement with the pore forming in XRD and cylindrical shape of the structure in $N_2$ adsorption-desorption isotherm. SBA-15 silica showed a large BET surface area of $603-698\;m^2/g$, a pore volume of $0.673-0.926\;cm^3/g$, a large pore diameter of 5.62-7.42 nm, and a thick pore wall of 3.31-4.37 nm. This result shows that as the aging temperature increases, the BET surface area, pore volume, and pore diameter increase but the pore wall thickness decreases. The BET surface areas in SM-2 and SM-3 are as large as $698\;m^2/g$. However, SM-2 has a large surface area and forms a thick pore wall, when the aging temperature is $100^{\circ}C$ and is synthesized into stable mesoporous SBA-15 silica.

• Journal of Adhesion and Interface
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• v.23 no.3
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• pp.94-99
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• 2022

Ternary phased graphene/silica/EVOH nanocomposite coating materials were prepared via sol-gel process and solution blending process. From both SEM observations and XRD analysis, the exfoliated structure and dispersion state of graphene nanosheets and silica particles in the nanocomposites as well as the intercalated and exfoliated structure of the prepared graphene oxide were confirmed. The incorporation of GrO and silica at appropriate content resulted in remarkable improvement in oxygen barrier property of the ternary phased nanocompoiste-coated BOPP films, compared with that of binary(silica/EVOH) phased nanocomposite coating films, however, at excess amount of GrO and silica, very slight variation was observed due to incomplete exfoliation, dispersion of graphene tactoids, and formation of micro cracks in the silica clusters. In addition, the transparency of nanocomposite-coated film was investigated by measuring the light transmittance as a function of GrO contents, suggesting the possibility for the application of food packaging films.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.315-323
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• 1998

$TiO_2$films of rutile and anatase phase have been prepared on silica glass substrates by the sol-gel method using $Ti(i-OC_3H_7)_4$. The effect of additives on the polymorph of $TiO_2$film has been examined in view of degree of crystallization. Third-order nonlinear optical properties of the both film have been investigated by the third harmonic generation method. The measured 3rd order nonlinear optical susceptibility of rutile and anatase thin films were about $1.4{\times}10^{-12}$ and $9.7{\times}10^{-13}$ esu, respectively.

• Journal of environmental and Sanitary engineering
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• v.13 no.3
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• pp.58-65
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• 1998

Monodispersed $SiO_2/ZnO$ composite fine powders were prepared by Sol-Gel processing and their surface electrical and UV absorbance properties were investigated. Pseudomorph ZnO fine powders were microcapsuled by $SiO_2/ZnO$ sol fabricated using TEOS[tetraethylorthosilicate, purity 98% and ethanol as a solvent with $NH_3$ catalyst. The effects of experimental parameters such as molar ratio of starting materials on the final particle size and shape of $SiO_2/ZnO$ composite fine powder were discussed. As a result, we could controlled the size of monodispersed $SiO_2/ZnO$ composite fine powders without agglomeration, as well as the good dispersibility in aquous solution. The prepared powders were observed to have the mean particle sizes of $0.26-0.78{\mu}m$ with standard deviations of $0.020-0.063{\mu}m$.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.135-141
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• 2020

The silica aerogels with benzene-bridged were designed to have uniform network structure, ordered pore structure, improved mechanical properties and excellent textural properties. Adding organic to enhance the mechanical properties of silica aerogels is a common method, but textural properties of aerogels with organic are reduced due to the organic-inorganic phase separation. In this paper, we use a simple and low-cost method to increase mechanical properties while maintaining textural properties of SiO2 aerogels. Two types of benzene-bridged precursors were prepared to study the effect of the number of hydroxyl band on the textural and mechanical properties. The porous silica aerogel was prepared by a simple, cost effective and pollution-free sol-gel method. This method does not require additional silylating reagents. The benzene-bridged silica aerogel samples prepared had excellent textural properties, high specific surface area (1,326 ㎡/g), porous structure and hydrophobicity (>140°). The mechanical strength of 2T4 is more than 5 times that of pure silica aerogel.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.1
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• pp.5-14
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• 2023

In this study, LiDAR-reflective black hollow-structured silica/titania(B-HST) materials are successfully synthesized by employing the NaBH₄ reduction and etching method on silica/titania core/shell(STCS) materials, which also effectively enhance near-infrared(NIR) reflectance. Moreover, core-etched supernatant solutions are collected and recycled for the synthesis of extracted silica(e-SiO₂) process, which successfully applies as filler materials for semiconductor epoxy molding compound(EMC). In detail, B-HST materials, fabricated by the sequential experimental steps of sol-gel, reduction, and sonication-mediated etching method, manifest blackness(L^*) of 13.2 similar to black paint and excellent NIR reflectance(31.1%). Consequently, B-HST materials are successfully prepared as LiDAR-reflective black materials. Additionally, core-etched supernatant solution with silanol precursors are employed for synthesis of homogeneous silica filler materials via sol-gel method. As-synthesized silica fillers are incorporated with epoxy resin and carbon black for the preparation of semiconductor EMC. Experimentally synthesized EMC exhibits comparable mechanical-chemical properties to commercial EMC. Conclusively, this study successfully proposes designing procedure and practical experimental method for simultaneously synthesizing the NIR-reflective black materials for self-driving vehicles and EMC materials for semiconductors, which are materials suitable for the industrial 4.0 era, and presented their applicability in future industries.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.327-334
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• 2018

Water-repellent coating solutions were prepared by sol-gel method using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as precursors. The solutions were spin-coated on a cold-rolled steel sheet and thermally cured to prepare a non-fluorine water-repellent coating films. The effects of molar ratios of MTMS/TEOS, water concentration and ammonia concentration on the hydrophobic properties of the coating films were studied. The contact angle of water on coating films prepared by varying the molar ratio of MTMS/TEOS to 1~20 showed a maximum value of $108^{\circ}$ when the MTMS/TEOS molar ratio was 10. With increasing water content, the coating films showed the larger contact angles and the better the water repellency. As the amount of ammonia added was increased, the contact angles of coating films were increased, showing the better the water repellency. It is considered that the larger the amount of ammonia added, the larger the size of the silica particles generated, which increases the surface roughness of the silica particles, thereby increasing the water repellency.