Conditions Governing the Formation of Lyotropic Liquid Crystals by Molecular Association

The lyotropic liquid crystals which are considered here are obtained with substances or mixtures of substances having amphiphilic molecules, the solvent being water. In order to understand the behaviour of these mixtures of amphiphilic substances it may be helpful to recall the behaviour of similar systems with only one amphiphilic substance, such as soaps or phospholipids. In fact lyotropic systems are also thermotropic and it is the cooperative action of the temperature and of the solvent which enables them to pass successively from the solid crystalline state to the liquid crystalline state and to the isotropic liquid or dissolved state.