Structure and characterization of sol-gel and aerogel materials and oxidation products from the reaction of (CH_3O)_4Si and C_(16)H_(33)Si(OCH_3)_3

摘要

Reactions of (CH_3O)_4Si and C_(16)H_(33)Si(OCH_3)_3 at various mole ratios were performed in methanol using base and acid catalysis.Sol-gel materials were formed that have low surface careas (approx 10 m~2/g).Subsequent supercritical drying using CO_2 at 40 degC produced materials that are very different than traditional aerogels,with surface areas around the same values as the corremelted upon heating.Spectroscopic characterization,using IR,~(29)Si and ~(13)C NMR revealed normal Si-O substitution as well as incorporation of the carbon chain into the Si framework.