The initial stage polymerization of silicic acid in aqueous solution was investigated by using a monosilicic acid solution prepared from hydrolysis of TMOS (Tetra-methyle-silicate).
Results obtained were as follows.
1) The silicic acid concentration in aqueous solution by ion resin method of sodium silicates decreased rapidly.
2) The silicic acid solution prepared from the hydrolysis of TMOS was stable on standing at 25°C. The rate of initial stage polymerization can be applied of the second-order reaction equation. Its initial stage polymerization were distinguished for three step in acid solution, and for two step in alkaline solution. The rate of polymerizationin alkaline solution proceeded greatly than this of in acid solution.
3) The activation energies for polymerization were 26.4 kcal/mol in water, 9.5 kcal/mol in acid solution.
From these results, it was found that the polymerization took place in a different mechanism by acid solution and alkaline solution, and formed ⁺H₂OSi (OH) ₃ in acid solution, (HO) ₃SiO^- in alkaline solution.