Switchable Cholesteric Liquid Crystals

The special optical properties of liquid crystals result from the ordered spatial arrangement of the molecules that make them up. This ordered arrangement can be "locked in" by polymerization of the molecules, to make devices with permanent optical properties. Chelix uses this technique to make its pigments and the optical components described in the Products section.

If liquid crystals are not locked into a particular arrangement, the molecules can be reoriented, or "switched." And switching the orientation of the molecules means switching the optical properties of the material. A scientist has many tools at her disposal to control reorientation or switching. Heating the liquid crystal or applying an electric field to it are two examples; modifying the surfaces in contact with the liquid crystal can also switch the liquid crystal's alignment. Electrically switchable liquid crystal systems are used in flat panel displays, light modulators, digital watches, shutters, and optical switches.

As another contribution to innovations in electrically switchable CLCs, Chelix has developed LuxVu Privacy Glazing. In a LuxVu window, the CLC molecules are normally oriented in random domains, within which the molecules are arranged in spirals. This orientation scatters light that passes through the material and gives the window a milky-white, opaque appearance. When an electric field of only a few volts is applied across the window, the molecules reorient themselves parallel to the electric field. This allows light to pass easily through the window without being scattered, and the window becomes transparent. (You can see an excellent demonstration of the LuxVu switching on the Chelix video, available soon.)