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Journal of Materials Science

, Volume 29, Issue 7, pp 1807–1817 | Cite as

Effect of solvents and catalysts on monolithicity and physical properties of silica aerogels

  • A. Venkateswara Rao
  • G. M. Pajonk
  • N. N. Parvathy
Papers

Abstract

The effect of various solvents and catalysts on the monolithicity and physical properties of silica aerogels is reported. The aerogels were prepared by hydrolysis and polycondensation of tetramethoxysilane, followed by hypercritical drying, using 6 solvents of different chain lengths, and 17 catalysts consisting of strong and weak acids, bases and their mixtures. It was found that solvents of longer chain lengths and strong basic catalysts resulted in semitransparent to opaque aerogels, whereas strong acids and their combinations with a weak basic catalyst produced transparent but cracked aerogels. While weak acids and their combinations with a weak base were found to produce shrunk and semitransparent (opaque for CH3COOH + NH4OH) aerogels, the best quality transparent, monolithic, low-density and refractive index, and large surface area aerogels were obtained for a combination of weak basic catalysts and solvents of shorter branching and chain lengths. The physical properties of the aerogels were studied by BET analysis, porosity, density, refractive index and optical transmission measurements.

Keywords

Refractive Index Chain Length Large Surface Area NH4OH Polycondensation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • A. Venkateswara Rao
    • 1
  • G. M. Pajonk
    • 1
  • N. N. Parvathy
    • 1
  1. 1.Laboratoire des Matériaux et Procédés CatalytiquesUniversité Claude Bernard Lyon IVilleurbanne CedexFrance

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