Hydrophilic Fumed Silica
Definition - What does Hydrophilic Fumed Silica mean?
This is a silica-based polymer with a tendency of absorbing moisture. It is used in high-technology fields or as an ingredient in paints, coatings, electronics and optical fibers industries.
There are various grades of this substance, which are defined by their amorphous structure. It is used to provide thixotropic properties in coatings and adhesives. It also assists in enhancing flow in the production industry, such as cosmetics and pharmaceuticals.
Corrosionpedia explains Hydrophilic Fumed Silica
Hydrophilic fumed silica, a light white powder, is brought about by the reaction of oxyhydrogen flame and volatile chlorosilanes (Silicon tetrachloride) to form molten spheres of silicon dioxide (and hydrogen chloride). The particle structure of the product depends on the place of application and the market. The variation of these sphere sizes is what brings about the grades.
The hydrophilic nature of fumed silica is a result of the attachment of hydroxyl groups onto silica atoms just at the surface of the particle; the product is now capable of hydrogen bonding—this makes it dispersible in water. This makes the product stable at room temperature, thus increasing the shelf life once opened.
By reacting hydrophilic fumed silica with reactive silanes, hydrophobic silica can be produced. The addition of this product in adhesives and coatings increases the surface energy adhesive force of the substrate.