Ultralight Silica Foams with a Hierarchical Pore Structure via a Surfactant-Free High Internal Phase Emulsion Processстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 24 октября 2018 г.
Аннотация:Ultralight silica aerogel is among the most versatile materials available for technical applications; however, its manufacture is complex and expensive. Here we report on a simple approach for preparation of silica foam monoliths with extremely low density and high specific surface area, which are close to those of aerogel. Our strategy is based on the effective stabilization of water-in-oil high internal phase emulsions by a hydrophobic silica precursor polymer, hyperbranched polyethoxysiloxane, due to its hydrolysis-induced amphiphilicity. After the conversion of PEOS to silica the emulsions are solidified without significant volume shrinkage. Mechanically strong macroporous silica monoliths are then obtained after removal of liquid components. According to nitrogen sorption data the resulting silica foams exhibit a high specific surface area and the foam skeletons consist of micro- and mesopores. The pore size, porosity as well as surface area can be regulated by varying pH and the concentration of the silica precursor in the oil phase. In addition, the pore size can also be effectively reduced by increasing homogenization intensity.