Figure 3.

Time-lapse observation of nPM (0.4 M) (left images) and 3F (0.4 M) (right images) hydrolysis and condensation at pH 1.7, 2.0, 2.5, and 3.0. Equal volumes of the two silanes were used, with nPM floating on top of the aqueous solution and 3F dropping to the bottom. Hydrolysis depletes the neat silane lenses, followed by onset of condensation and turbidity due to light scattering by the sol. Aggregation of the particles in the sol clears the solution as particles drop to the bottom of the reaction tubes.