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Organically Modified Silicate Aerogels, “Aeromosils”

Published online by Cambridge University Press:  10 February 2011

S. J. Kramer
Affiliation:
University of California, Department of Materials Science and Engineering, Los Angeles, CA 90095
F. Rubio-Alonso
Affiliation:
Instituto de Ceramica y Vidrio (CSIC), Metodos Fisico-Qimicos, Madrid, Spain
J. D. Mackenzie
Affiliation:
University of California, Department of Materials Science and Engineering, Los Angeles, CA 90095
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Abstract

Aerogels derived from sol-gel oxides such as silica have become quite scientifically popular because of their extremely low densities, high surface areas, and their interesting optical, dielectric, thermal and acoustic properties. However, their commercial applicability has thus far been rather limited, due in great part to their brittleness and hydrophilicity. In prior work by our research group, modifying silicate gel structures with flexible, organic containing polymers such as polydimethylsiloxane imparted significant compliance (even rubbery behavior) and hydrophobicity. These materials have been referred to as Ormosils. This study expounds on our current efort to extend these desirable properties to aerogels, and in-so-doing, creating novel “Aeromosils”.

Reactive incorporation of hydroxy-terminal polydimethylsiloxane (PDMS) into silica sol-gels was made using both acid and two-step acid/base catalyzed processes. Aerogels were derived by employing the supercritical CO2 technique. Analyses of microstructure were made using nitrogen adsorption (BET surface area and pore size distribution), and some mechanical strengths were derived from tensile strength testing. Interesting Aeromosil properties obtained include optical transparency, surface areas of up to 1200 m2/g, rubberiness, and better strength than corresponding silica aerogels with elongations at break exceeding 5% in some cases.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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