نتایج جستجو برای: thermoreversible gels aerogels

تعداد نتایج: 24213  

Journal: :Science 2007
Santanu Bag Pantelis N Trikalitis Peter J Chupas Gerasimos S Armatas Mercouri G Kanatzidis

Inorganic porous materials are being developed for use as molecular sieves, ion exchangers, and catalysts, but most are oxides. We show that various sulfide and selenide clusters, when bound to metal ions, yield gels having porous frameworks. These gels are transformed to aerogels after supercritical drying with carbon dioxide. The aerogels have high internal surface area (up to 327 square mete...

2004
Sushil Shrinivasan Michael C. Breadmore Bouvard Hosticka James P. Landers Pamela M. Norris

Silica aerogels were prepared via the sol–gel process using tetramethoxysilane (TMOS) as the precursor and polyethylene oxide (PEO) of molecular weights 10,000 and 100,000 to provide a polymeric template for gelation. The experiments included eleven different formulations ranging from 100% 10,000MW PEO to 100% 100,000MW PEO in 10% increments. The total concentration of PEO was kept constant thr...

Journal: :ACS nano 2013
Michael Rousseas Anna P Goldstein William Mickelson Marcus A Worsley Leta Woo Alex Zettl

sp(2)-Bonded boron nitride aerogels are synthesized from graphene aerogels via carbothermal reduction of boron oxide and simultaneous nitridation. The color and chemical composition of the original gel change dramatically, while structural features down to the nanometer scale are maintained, suggesting a direct conversion of the carbon lattice to boron nitride. Scanning and transmission electro...

Journal: :Chemical reviews 2002
Alain C Pierre Gérard M Pajonk

In the present review, aerogels designate dried gels with a very high relative pore volume. These are versatile materials that are synthesized in a first step by low-temperature traditional sol-gel chemistry. However, while in the final step most wet gels are often dried by evaporation to produce so-called xerogels, aerogels are dried by other techniques, essentially supercritical drying. As a ...

2008
F. Pérez-Caballero A. Galindo F. Montilla

5-methylresorcinol and the technical mixture of oil-shale phenolic compounds were applied for carbon aerogel preparation. Gels, which were prepared via base catalyzed polymerization were dried under supercritical conditions and subsequent pyrolysis of obtained dry aerogels led to carbon aerogels. Activation of carbon aerogel with CO2 and H2O was performed and porosity and the specific surface a...

Journal: :Journal of nanoscience and nanotechnology 2012
L Durães M Ochoa N Rocha R Patrício N Duarte V Redondo A Portugal

Nanostructured silica based xerogels and aerogels are prepared by sol-gel technology, using methyltrimethoxysilane as precursor. The influence of the drying method and conditions on the microstructure of the obtained materials is investigated, since the drying stage has a critical influence on their porosity. Two types of drying methods were used: atmospheric pressure drying (evaporative), to p...

Journal: :Catalysts 2022

Due to their self-supporting and nanoparticulate structure, metal aerogels have emerged as excellent electrocatalysts, especially in the light of shift renewable energy cycles. While a large number synthesis parameters already been studied depth, only superficial attention has paid solvent. In order investigate influence this parameter with respect gelation time, crystallinity, morphology, or p...

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