Hexagonal phase
A hexagonal phase of lyotropic liquid crystal is formed by some amphiphilic molecules when they are mixed with water or another polar solvent.
In this phase, the amphiphile molecules are aggregated into cylindrical structures of indefinite length and these cylindrical aggregates are disposed on a hexagonal lattice, giving the phase long-range orientational order.
In normal topology hexagonal phases, which are formed by type I amphiphiles, the hydrocarbon chains are contained within the cylindrical aggregates such that the polar-apolar interface has a positive mean curvature.
When viewed by polarization microscopy, thin films of both normal and inverse topology hexagonal phases exhibit birefringence, giving rise to characteristic optical textures.
Size and shapes of lamellar, micellar and hexagonal phases of lipid bilayer phase behavior and mixed lipid polymorphism in aqueous dispersions can be easily identified and characterized by negative staining transmission electron microscopy too.
