This describes a class of glassy liquid crystal (GLC) materials for optical devices with outstanding mechanical properties for device fabrication and durability.
Optical quality films prepared from these materials can be used for circular polarizers, circular polarized fluorescence films, optical notch filters and reflectors, filters for laser protection, latching electro-optical devices for optical communication, and low threshold, efficient circularly polarized lasers.
The uniqueness of this material class is reflected in the new term glassy liquid crystals. These materials are not polymers, but discrete molecules of low to moderate (<2000) molecular weight. The materials have excellent film- and fiber-forming abilities and morphological stability. Because of superior chemical purity, favorable rheological properties and their short, uniform mechanical relaxation time, these GLCs are much easier to process into defect-free films than liquid crystal polymers. Conventional liquid crystal polymers generally are difficult to fabricate into large area thin films due to high melt viscosity. Because the GLC materials have high glass transition temperatures, they show long-term stability and environmental durability against thermally-activated re-crystallization.
Films can be made with both right and left-handed polarization with selective reflection wavelength continuously tunable from blue through infrared regions.
This invention provides a method for making glassy liquid crystal (GLC) materials, which uses readily available starting materials and an efficient, environmentally friendly synthesis and purification procedure. A range of GLC materials have been synthesized for optical device fabrication and systematic investigation of structure-property relationships. A glass transition temperature (Tg) of 73°C and clearing temperature (Tc ) of 295°C have been achieved in a representative material. The clearing point indicates the temperature at which the liquid crystal properties disappear. A high clearing temperature provides a wide temperature range of applicability.