# Colloidal Dispersion

## Definition

Colloidal dispersions are a class of soft materials. The term typically refers to a material consisting of solid particles spread throughout a fluid. According to Jones [1, p. 49], colloidal particles must have dimensions on the order of 10$\mu$m or smaller.

Witten [2, p. 113] distinguishes between colloids (solid particles in liquid), emulsions (liquid drops in another liquid), and foams (gas bubbles in a liquid), while Jones [1, p. 1] includes emulsions as a subgroup of colloids. One can also find definitions for colloidal dispersions which include other combinations of solid, liquid, and gas phases.

## References

[1] R. Jones, "Soft Condensed Matter," Oxford University Press Inc., New York (2002).

[2] T. Witten, "Structured Fluids: Polymers, Colloids, Surfactants," Oxford University Press Inc., New York (2004).