Glassy Liquid Crystals (GLCs) for Optical Polarizing Films

Brief Description
Brief Description:
This is a class of glass-forming liquid crystal (GLC) compositions for optical devices with outstanding mechanical properties for device fabrication and durability.  Optical quality films prepared from these compositions demonstrate strong selective reflection and circular polarization, as well as circularly polarized photoluminescence.

The materials can be used for high efficiency polarizers in flat panel displays, optical notch filters for laser protection, latching electro-optical devices for optical communication, interference pigments and for optical information storage.    The synthesis route leads to a novel class of compositions of matter, with very useful optical properties, including selective reflection and circular polarization in the UV.  Mixtures of materials with opposite chirality, at varying ratios, result in films with selective reflection and circular polarization anywhere in the visible to the infrared.  

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.  
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.  Glass transition temperatures (Tg ) up to 130°C and clearing temperatures (Tc ) up to 347°C have been achieved. The clearing point indicates the temperature at which the liquid crystal properties disappear.  A high clearing temperature provides a wide temperature range of applicability.
Patent Information:
Title Country Patent No. Issued Date
Glassy Chiral-Nematic Liquid Crystals and Optical Devices Containing Same United States 7,001,648 2/21/2006
For Information, Contact:
John FahnerVihtelic
Senior Licensing Manager
University of Rochester
Shaw-Horng Chen
Huang-Ming Philip Chen