Fumed silica is an important functional additive in waterborne coatings, and its dispersion effect directly affects the rheology, stability, and final performance of the coatings. The following is a comprehensive technical guide to optimizing the dispersion of fumed silica:

Dispersion Principles and Common Problems
The surface of fumed silica contains a large number of hydroxyl groups, which form a three-dimensional network structure through hydrogen bonding, giving the coating excellent thixotropic and anti-settling properties. In waterborne systems, dispersion faces the following challenges:

Agglomeration Problems: High surface energy leads to easy particle agglomeration, forming aggregates.
Difficulty in Wetting: High interfacial tension between hydrophilic surfaces and waterborne media.
Process Sensitivity: Insufficient or excessive dispersion will affect performance.

Dispersant Selection and Use
Dispersant Types
Anionic: Generates electrostatic repulsion through the electric double layer principle.
Nonionic: Provides steric hindrance to prevent re-agglomeration.
Polymer: Combines both electrostatic and steric hindrance effects.