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Lyotropic liquid crystals are obtained when an appropriate concentration of material is dissolved in some solvent. The most common systems are those formed by water and amphiphilic molecules (molecules that possess a hydrophilic part that interacts strongly with water and a hydrophobic part that is water insoluble) such as soaps, detergents, and lipids. Here the most important variable controlling the existence of the liquid crystalline phase is the amount of solvent (or concentration). There are quite a number of phases observed in such water‐amphiphilic systems, as the composition and temperature are varied; some appear as spherical micelles, and others possess ordered structures with 1‐, 2‐, or 3‐D positional order.

Examples of these kinds of molecules are soaps (Figure 1.8) and various phospholipids like those present in cell membranes. Lyotropic liquid crystals are of interest in biological studies [7].

Figure 1.8. Chemical structure and cartoon representation of sodium dodecyl sulfate (soap) forming micelles.