Polarized optical microscopy mesophases formation

Cubic phases (Cub) are mesophases of cubic symmetry (Diele, 2002). Because of their high symmetry, their physical properties are no Imiger anisotropic. No defect texture is observed by polarizing optical microscopy (POM vide infra) and the image between crossed polarizers remains black. The cubic mesophases are very viscous and often their formation kinetics is very slow. Although cubic mesophases are very common for lyotropic LCs, where a cubic phase is possible between any pair of phases, there are only relatively few examples of cubic mesophases in thermotropic LCs. Whereas a cubic mesophase can be relatively easily detected when it is present between two anisotmpic mesophases, it is difficult to observe the formation of the cubic phase when it is formed by cooling an isotropic liquid. In this case, a deformatirMi of air bubbles in the melt is observed, as well as a sharp increase in the viscosity of the liquid. 

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