Before modification, there are three hydroxyl groups on the surface of gaseous silica. One is the isolated free hydroxyl group, which is "linked" on the surface of particles with a certain spacing. The second is the associated hydroxyl groups that are linked and form hydrogen bonds; The third is a twin hydroxyl group, two hydroxyl groups attached to a silicon atom. The modification of gaseous silica is to choose the appropriate surface treatment agent to react with the hydroxyl group on the surface of silica through a certain process, so as to reduce the amount of silicon hydroxyl group on the surface and make the surface of gaseous silica hydrophobic. Generally speaking, the volatile substances that can react with the hydroxyl group on the surface of white carbon black can be used as modifiers.

Commonly used modifiers include organochlorine silanes, silane coupling agents, alcohols, amines:
(1) Organochlorosilane as a modifier, commonly used is dimethyl dichlorosilane and trimethyl chlorosilane.
(2) silane coupling agent as a modifier, commonly used are hexamethyldisilane, hexamethylvinyl silane, vinyl ethoxy silane, etc.
(3) Alcohol compounds as modifiers.
(4) Amines were used as modifiers.



Dimethylchlorosilane : https://www.siliconematerial.net/product-dimethylchlorosilane-iota-m2.html 
Trimethylchlorosilane : https://www.siliconematerial.net/product-trimethylchlorosilane-m3-iota-m3.html
Hexamethyldisilazane(HMDS) : https://www.siliconematerial.net/product-hexamethyldisilazane%20hmds-iota-011.html