Modification of silica via a chemical interaction
involves a modification of its surface with modifying
agents (i. e., silanes) or grafting polymers. The most
common way of making silica hydrophobic and polymer
compatible, is silanization. We can find a long list of
silane coupling agents that generally have hydrolysable
and organofunctional ends and can be represented as
RSiX3. X stands for hydrolysable groups, typically
chloro, methoxy or etoxy gropus, and R stands for the
organo group that has to be chosen according to the
properties of the polymer. Silanes are attached to the
silica surface through the reaction of hydrolysable
groups with the hydroxyl groups on the silica surface
while the alkyl chains interact with the polymer26
(Figure 2).