Lyotropic liquid crystal

In turn, they generate the long-range order of the phases, with the solvent molecules filling the space around the compounds to provide fluidity to the system.

As the concentration of amphiphilic molecules is increased, several different type of lyotropic liquid crystal structures occur in solution.

The aggregates formed by amphiphilic molecules are characterised by structures in which the hydrophilic head-groups expose their surface to aqueous solution, shielding the hydrophobic chains from contact with water.

True lyotropic liquid crystalline phases are formed as the concentration of amphiphile in water is increased beyond the point where the micellar aggregates are forced to be disposed regularly in space.

For amphiphiles that consist of a single hydrocarbon chain the concentration at which the first liquid crystalline phases are formed is typically in the range 25–30 wt%.

[citation needed] The simplest liquid crystalline phase that is formed by spherical micelles is the 'micellar cubic', denoted by the symbol I1.

At higher amphiphile concentrations the micelles fuse to form cylindrical aggregates of indefinite length, and these cylinders are arranged on a long-ranged hexagonal lattice.

[7] The term lyotropic has also been applied to the liquid crystalline phases that are formed by certain polymeric materials, particularly those consisting of rigid rod-like macromolecules, when they are mixed with appropriate solvents.

It is noted that in these cases the solvent acts to lower the melting point of the materials thereby enabling the liquid crystalline phases to be accessible.

The issue of the existence of such a lyotropic phase was raised by Langmuir in 1938,[12] but remained an open question for a very long time and was only confirmed recently.

[13][14] With the rapid development of nanosciences, and the synthesis of many new anisotropic 2D nanoparticles, the number of such Nematic mesophase based on 2D nanosheet has increased quickly, with, for example graphene oxide colloidal suspensions.

A highly viscous cubic phase gel made of polysorbate 80 , water, and liquid paraffin .
Schematic showing the aggregation of amphiphiles into micelles and then into lyotropic liquid crystalline phases as a function of amphiphile concentration and of temperature.