Abstract

A colloid comprises a collection of small particles, droplets, or bubbles of one phase having at least one dimension between ~ 1 and 1000 nm, and dispersed in a second phase. Either or both phases may be in gas, liquid, solid, or supercritical phase states. Another property that distinguishes colloidal dispersions is the extremely large area of the interface between the two phases compared with the mass of the dispersed phase. A consequence is that any chemical and physical phenomena that depend on the existence of an interface become very prominent in colloidal dispersions. Colloidal systems are important because they feature prominently, in both desirable and undesirable contexts, in a wide variety of practical disciplines, products and industrial processes. The problems associated with colloids are usually interdisciplinary in nature and a broad scientific base is required to understand them completely. This article provides an introduction to the field of colloids, emphasizing the wide range of practical and industrial applications.