The morphology of silica particles dispersed in ethanol was
observed by TEM. The effect of in-situ and ex-situ modifications
on shape of silica particles when the HMDS amount was 6 ml are
shown in Fig. 6. The SP exhibits typical spherical shape, as shown
in Fig. 6a. The shape of ESP, as shown in Fig. 6b, is close to the typical
spherical shape. However, Fig. 6c shows that the shape of ISP
changes greatly and does not maintain the typical spherical shape.
The reasons could be concluded as follows: In-situ modification
was introduced into the synthetic process of silica particles. As a
result, the random reaction between HMDS and hydroxyl groups
on silica surface increased the irregular degree of the silica particles
shape greatly. However, ex-situ modification did not participate
in the synthetic process of silica particles, which could not
change the spherical shape of silica particles remarkably.