Perdeuterated cyanobiphenyl liquid crystals for infrared applications

Perdeuterated 4'-pentyl-4-cyanobiphenyl (D5CB) was synthesized and its physical properties evaluated and compared to those of 5CB. D5CB retains physical properties similar to those of 5CB, such as phase transition temperatures, dielectric constants, and refractive indices. An outstanding feature of D5CB is that it exhibits a much cleaner and reduced infrared absorption. Perdeuteration, therefore, extends the usable range of liquid crystals to the mid infrared by significantly reducing the absorption in the near infrared, which is essential for telecom applications

Birefringent properties of cyclic block copolymers and low-retardation-film development

Cyclic block copolymers (CBCs) are a new class of optical polymers made by fully hydrogenating block copolymers of styrene and conjugated diene. This class of materials has excellent optical transparency, photostability, and good thermal resistance. By changing the copolymer composition and the resulting block-copolymer morphology, a unique set of birefringence properties can be achieved. The focus of this work was to study various sources of birefringence in block copolymers using a series of model CBC materials. One particularly interesting finding relates to the development of an ultra-low-phase-retardation CBC film. Unlike the conventional approach of using an additive or blend, a CBC film prepared by melt extrusion can readily achieve near-zero retardation in both the film plane and thickness direction. This nearly isotropic CBC film is useful as a polarizer protection film in flat-panel displays. When used as the inner protective layer of a polarizer, CBC film helps to reduce the color shift of IPS-LCDs at oblique angles and offer a wider viewing angle

New liquid crystal materials enabling revolutionary display devices

The Display and Beam Steering Thrust of the AFOSR Liquid Crystal MURI addressed key materials and device technology issues affecting performance of liquid crystal (LC) electro-optic (EO) devices, particularly device structures useful in information Displays and for Laser Beam Steering and Switching. Two basic themes were development of bulk LCs having high performance characteristics (nematic LCs, and chiral smectic LC devices having analog response), and development of novel LC electro-optic structures. Research on novel device structures led to advances in LC alignment and on photonic band-gap materials