Preparation of high porosity xerogels by chemical surface modification.

US5565142A · kind A · utility

Inventors

• Ravindra Deshpande · Lancaster, US
• Douglas M. Smith · Albuquerque, US
• C. Jeffrey Brinker · Albuquerque, US

Key dates

• Filing date: Apr 28, 1993
• Grant date: Oct 15, 1996
• Expiry date: Apr 28, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2995
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

This invention provides an extremely porous xerogel dried at vacuum-to-below supercritical pressures but having the properties of aerogels which are typically dried at supercritical pressures. This is done by reacting the internal pore surface of the wet gel with organic substances in order to change the contact angle of the fluid meniscus in the pores during drying. Shrinkage of the gel (which is normally prevented by use of high autoclave pressures, such that the pore fluid is at temperature and pressure above its critical values) is avoided even at vacuum or ambient pressures.