Surface Energy Aspects of Silica

Surface density 2 to 8 OH per nm (depending on specific area and production process) Strong reactivity with water (moisture)  

Dispersive and polar components would therefore appear as a key information regarding the surface activity of silica, unfortunately available only through research literature on a few commercial grades, and with differences in tests conditions as used by the authors. Table 4.11 gives published data on commercial silica grades, as compiled in the literature. 

Anhydrous, fumed, silicas have a higher li than hydrated, precipitated silicas and, moreover, the lower the specific surface area, the lower the dispersive component, irrespective of the production process. According to Wang et al., the difference in the dispersive component between both types of synthetic silica might depend on the surface topology of their particles, and less on the concentration of hydroxyl groups. 

---