Hydrophobic silica aerogels

Yokogawa, Hiroshi; Yokoyama, Masaru

doi:10.1016/0022-3093(95)00086-0

Cited by 226 publications

(111 citation statements)

References 2 publications

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“…To attain aerogel with n ∼ 1.08, we used only DMF as the solvent, whereas we generally used a mixture of DMF and methanol at n ∼ 1.05. After aging the wet gel, it was detached from the mold in an ethanol bath, and we performed a hydrophobic treatment by adding hexamethyldisilazane into the ethanol bath [17]. After removing impurities from the wet gel by repeatedly replacing the ethanol, we finally obtained an aerogel using the supercritical carbon dioxide drying method.…”

Section: Aerogel Fabricationmentioning

confidence: 99%

Fabrication of silica aerogel with n=1.08 for e+/μ+ separation in a threshold Cherenkov counter of the J-PARC TREK/E36 experiment

Tabata

Toyoda

Kawai

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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Fabrication of silica aerogel with n = 1.08 for e + /µ + separation in a threshold Cherenkov counter of the J-PARC TREK/E36 experiment AbstractThis study presents the development of hydrophobic silica aerogel for use as a radiator in threshold-type Cherenkov counters. These counters are to be used for separating positrons and positive muons produced by kaon decay in the J-PARC TREK/E36 experiment. We chose to employ aerogel with a refractive index of 1.08 to identify charged particles with momenta of approximately 240 MeV/c, and the radiator block shape was designed with a trapezoidal cross-section to fit the barrel region surrounding the kaon stopping target in the center of the TREK/E36 detector system. Including spares, we obtained 30 crack-free aerogel blocks segmented into two layers, each layer having a thickness of 2 cm and a length of 18 cm, to fill 12 counter modules. Optical measurements showed that the produced aerogel tiles had the required refractive indices and transparency.

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Section: Aerogel Fabricationmentioning

confidence: 99%

Fabrication of silica aerogel with n=1.08 for e+/μ+ separation in a threshold Cherenkov counter of the J-PARC TREK/E36 experiment

Tabata

Toyoda

Kawai

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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“…In addition, since hydrophilic surfaces of bare silica aerogels are not stable in a humid condition, a hydrophobizing process using a coupling agent such as hexamethyldisilazane (HMDS) is needed. 19) We have prepared mechanically strong and flexible aerogels with high transparency and low density by preparing aerogels with an organic inorganic hybrid composition. We used methyltrimethoxysilane (MTMS) as the precursor and the ideal product obtained from MTMS is methylsilsesquioxane (MSQ, CH 3 SiO 1.5 ).…”

Section: Preparationmentioning

confidence: 99%

Advances in monolithic porous materials tailored in liquid media: around inorganic oxides and organic polymers

Kanamori

2012

J. Ceram. Soc. Japan

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This review briefly surveys, with an emphasis on the author's works, porous monoliths tailored by liquid-phase synthesis. Porous structures ranging from mesopore to macropore regions are induced in sol gel polymerizing systems, which yield various porous materials such as inorganic oxides, organic inorganic hybrids, crosslinked polymers, and carbons. It should particularly be noted that the networks must be homogeneous enough to obtain monolithic materials with fine pore structures, and for this purpose, the chemical reactions must be carefully designed and controlled. With exemplifying alkoxy-derived sol gel systems and controlled/ living radical polymerization systems, pore formations and applications of resultant materials are demonstrated.

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“…TMOS is expensive and potentially harmful to the eyes, however, and it is consequently unsuitable for industrialization. Aerogels have been synthesized using methylsilicate 51 (tetramer of TMOS), which has improved toxicity relative to TMOS 4) but is just as expensive. Waterglass, on the other hand, is a more attractive raw material for practical reasons such as lower cost, superior safety, and supply stability relative to alkoxysilanes.…”

Section: Introductionmentioning

confidence: 99%

“…4) While monoliths of higher quality can be derived through supercritical drying, the process requires a large amount of solvent and a long time to conduct solvent substitution before drying. The enormous investments required for facilities and batch processing pose further obstacles to large-scale industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Effect of organic hydrophobic groups on the pore structure and thermal properties of waterglass-based silica xerogels

Oikawa

Toyota

Sakatani

et al. 2017

J. Ceram. Soc. Japan

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Hydrophobic silica xerogels containing trimethylsilyl (TMS) and dimethylsilyl (DMS) organic hydrophobic functional groups were synthesized using waterglass as the starting material. Five types of hydrophobic silica xerogels with varying surface coverages of the TMS and DMS groups were synthesized by changing the molecular structure of siloxane, which was used to introduce the hydrophobic moieties into the hydrogel and to investigate the resultant surface structures and thermal characteristics. The results revealed that the relative area of silica xerogels was smaller with a higher coverage of DMS groups. In addition, the thermal decomposition temperature of the silyl group shifted to higher temperatures, and the weight reduction during heating was also relatively limited in the above samples.

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Hydrophobic silica aerogels

Cited by 226 publications

References 2 publications

Fabrication of silica aerogel with n=1.08 for e+/μ+ separation in a threshold Cherenkov counter of the J-PARC TREK/E36 experiment

Fabrication of silica aerogel with n=1.08 for e+/μ+ separation in a threshold Cherenkov counter of the J-PARC TREK/E36 experiment

Advances in monolithic porous materials tailored in liquid media: around inorganic oxides and organic polymers

Effect of organic hydrophobic groups on the pore structure and thermal properties of waterglass-based silica xerogels

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