• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.1-11
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• 2011

Tetraethoxysilane(TEOS) as a silica precursor and hydrochloric acid as an acid catalyst have been used in a surfactant-template synthesis of micrometer-sized mesoporous silica microspheres based on the macroemulsion technique. Increase in the concentration of tetraethoxysilane of the reaction mixture has a serious destructive effect on the particle shape and pore structure. As the acid concentration increases, relatively small microspheres are formed without destroying their spherical morphology of the particles as well as the pore structures. However, due to the attractive interaction between particles in an acidic condition, strong silica agglomerates are formed, and therefore are subject to a post-ultrasonic treatment to separate into an individual single particle.

• Membrane Journal
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• v.26 no.5
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• pp.391-400
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• 2016

In this work, novel thin film composite (TFC) forward osmosis (FO) membranes are developed via interfacial polymerization on the polysulfone (PS) substrate, using TEOS as the a sol-gel reagent to form hydrophilic interlayer polymer between PS and polyamide (PA). The PS substrate was cast on a very thin polyester nonwoven to reduce membrane resistance. With the incorporation of TEOS (tetraethoxy silane) polymer in the interface between PS and PA, the formed TFC FO membrane exhibits better hydrophilicity and improved water flux, and therefore superior membrane performance. By changing the polymerization sequence of PA interfacial polymerization and TEOS sol-gel condensation, the surface properties and performance of FO membranes are changed significantly. The permeability of FO membranes were estimated using the bench-scale FO test equipment. The distribution of the polysiloxane on composite membrane and morphology are also studied with FE-SEM and EDAX. The PS_PA_TEOS membrane showed highly enhanced water flux (79.2 LMH) but reverse salt flux (RSF) value (7.10 GMH) also increased. However, the flux of PS_TEOS_PA membrane increased moderately (54.1 LMH) without increasing RSF value (1.60 GMH) compare with PS_PA membrane.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.409-414
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• 2019

Silica and polymethylsilsesquioxane (PMSQ) are silicone powders widely used as cosmetics. We synthesized silica-PMSQ composites via sol-gel method using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as precursors of silica and PMSQ, respectively. Shape of the composites was controlled by varying the ratios of TEOS and MTMS, which were used as silane monomers. Silica-PMSQ composites showed three different shapes, which were sphere-shape, raspberry- shape, and donut- shape. All of them had soft touch, easy water dispersion, and soft focus effect in common. However, each shape showed some differences in sense of use, adhesion, and strength of the soft focus effect. Raspberry-shape composite had the strongest soft focus effect, donut-shape one had the strongest adhesion, and sphere-shape one had the best in softness. Thus, it is concluded that by varying the ratios of TEOS and MTMS silica-PMSQ composites could be easily synthesized into different shapes, providing various functions. This method can be applied to manufacture functional cosmetics.

• 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.

• Membrane Journal
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• v.24 no.3
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• pp.177-184
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• 2014

Silica membranes with high permeability were prepared using colloidal and polymeric silica sols on a porous stainless steel-tube support by a DRFF and SRFF method. Silica sols were derived with tetraethylorthosilicate (TEOS) by sol-gel method and analyzed with DLS, FE-SEM, and $N_2$ adsorption. The coating of the intermediate layer with colloidal silica sol on the stainless steel-tube support led to a denser surface morphology of the membrane along with a considerable reduction in the number of surface defect. As the polymeric silica sol enclosed the colloidal silica sol with spherical particles during the SRFF method, the separation-layer-coated silica membrane showed a denser surface than the intermediate layer. Moreover, the silica membranes showed high hydrogen gas permeability of $(6.63-9.21){\times}10^{-5}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$ with low $H_2/N_2$ perm-selectivity (2.9-3.1) at room temperatures.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.386-390
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• 2007

In this study, polyurethane prepolymers were synthesized from polycaprolactonediol (PCDs. M.W. 530, 830, 1000, 1250, and 2000) and polycaprolactonetriol (PCTs. M.W. 300 and 900), and hexamethylenediisocyanate (HMDI). Polyurethane beads was prepared from the different prepolymers by a two-step suspension polymerization. The particle size of polyurethane beads was investigated by particle size analyzer. The beads were $10{\sim}30{\mu}m$ in size. The structure of beads was confirmed by FT-IR spectrometer. Their thermal properties were analyzed by TGA. Glass transition temperatures ($T_g$) of the beads were in the range of $-23{\sim}-53^{\circ}C$ and decreased with the increase of the PCD molecular weight. In order to prevention the cohesion of beads, the beads were coated with tetraethoxysilane (TEOS).