CARBON COATING OF SILICA SURFACE .2. PYROLYSIS OF SILICA-GELS ESTERIFIED WITH PHENOLS

A silica gel was esterified with phenols at 300 or 350 degrees C and pyrolyzed at 700 degrees C under vacuum, yielding carbon-coated silica gels (CSG). Their surface properties were compared with those of CSG prepared by a conventional chemical vapor deposition (CVD) method, in which benzene was used as a carbon source. This new method, named the ester pyrolysis method, was found to have the following advantages: the method considerably improved the percentage of carbon coating of the silica surface compared with the benzene-CVD method, the carbon film was formed uniformly on both the inner and the outer surfaces of the silica gel, and the carbon hardly blocked the pores of the silica gel. (C) 1995 Academic Press, Inc.