有機溶媒中でのケイ酸の縮合によるゲル状シリカガラスの合成

抄録

The preparation of a gel-like silica glass from silicic acid was investigated. This method requires the processes: (1) Extraction of silicic acid with tetrahydrofuran from an aqueous sodium metasilicate solution neutralized with hydrochloric acid, followed by concentration of an extracted solution to give “concentrated silicic acid”, (2) Preparation of silicic acid solutions with various concentrations and solvents to allow a moderate condensation, and (3) Formation of a gel plate by condensation polymerization of silicic acid with evaporation of solvent. Since gels are formed by the condensation which is highly dependent on the evaporation of solvent. Alcohols, acetone, methyl ethyl ketone, THF, formamide, dimethyl formamide, acetonitrile and water were used as solvent. Pieces of silica gels were obtained easily, but plate was not obtainable unless condensation was controlled. Gel plates without cracks were obtained when the solutions with the molar ratio (solvent/SiO₂) of 1-5 were aged.