Association colloids micelles

Colloids are introduced in the second half of the chapter. The various classifications of colloid types are discussed, together with ways of forming, sustaining and destroying colloids, i.e. colloid stability. Finally, association colloids ( micelles ) are discussed. 

Association colloids are aggregates or associations of amphipathic surface active molecules. These molecules are soluble in the solvent, and their molecular dimensions are below the colloidal size range. When present in solution at concentrations above a certain critical value (the critical micelle concentration), these molecules tend to form association colloids (micelles) (Fig. 1). 

Although the impact of this molecular-level effect is quite small (negligible in most cases), it can, under some circumstances, produce an appreciable energetic effect—repulsive in the case of two approaching surfaces—that is, it will be difficult to displace the last molecular layers separating the surfaces—or attractive in the separation of two contacting (adhesive) surfaces. These topics will appear again in Chapters 10 (on colloids and colloidal stability), 15 on association colloids micelles, vesicles and membranes), and 19 on adhesion). 

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