Building Blocks for Liquid Crystals

來源：Seebio.cn作者：西寶生物人氣：-發(fā)表時間：2012-03-12 09:30:27【大中小】

The first nematic liquid crystal material, a Schiff base types, were sensitive to moisture, while azoxybenzene types were sensitive to light. Therefore, research to improve the stability of liquid crystals to moisture and lights was undertaken by many. The chemically stable biphenylcarboxylates and cyanobiphenyls were developed one after another. The cyanobiphenyls were found to exceptional in possessing the necessary properties of display material. They exhibited low viscosity and low voltage operation, leading to many reports on the cyanobiphenyls. The phenylcyclohexane based liquid crystals also have low viscosity and high respons speeds, thus drawing to attention their use as display material. Furthermore, these bicylic liquid crystals were moddified by the addition of benzene and cyclohexane rings to produce tricyclic and tetracyclic liquid crystals. As a result, the upper range of temperature was increased. In recent years, further improvements in the various physical properties were made by introduction of fluorine and another functional groups to the liquid crystals, and there are now widely used. The optically active compounds are important components of chiral nematic liquid crystals and chiral smectic liquid crystals. More recently, antiferroelectric liquid crystals of the chiral smectic liquid crystal type, are now undergoing vigorous synthetic studies to develop novel liquid crystal compounds. Larger high-resolution display, are the target for the next generation of liquid crystal materials.