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History of Liquid Crystal Research

History of Liquid Crystal Research. The first observations. W. Heintz reported that stearin melted from a solid to a cloudy liquid at 52°C, changed at 58°C to an opaque and at 62.5°C to a clear liquid.

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History of Liquid Crystal Research

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  1. History of Liquid Crystal Research The first observations • W. Heintz reported that stearin melted from a solid to a cloudy liquid at 52°C, changed at 58°C to an opaque and at 62.5°C to a clear liquid. • 1877 Otto Lehmann invented the heating stage microscope and investigate the phase transitions of various substances with a heating stage polarizing microscope. • till 1888 Researchers in different fields such as chemistry, biology, medicine, and physics observed that some biologically derived materials display an opaque liquid state between the birefringent solid and the clear liquid state. Compounds synthesized from cholesterol also showed blue colors when cooled from their isotropic melt.

  2. A new phase of matter 1888 The Austrian botanist Friedrich Reinitzer, interested in the biological function of cholesterol in plants, was looking at the melting behaviour of an organic substance related to cholesterol. He observed, as W. Heintz did with stearin 38 years before, that the substance melted to a cloudy liquid at 145.5°C and became a clear liquid at 178.5°C. He repeated an earlier observation which showed that upon cooling the clear liquid, a brief appearance of blue color could be seen at the transition temperature, and that a blue violet color appeared just before crystallization. Discussion with Lehmann and others led to the identification of a new phase of matter called the liquid crystal phase.

  3. Early Foundations • The first synthetic liquid crystal, p-azoxyanisole, was produced by Gatterman and Ritschke. (1900) D. Vorlaender, and coworkers were the first to synthesize a thermotropic smectic compound. 1907 Vorlaender published a paper detailing rules of liquid crystallinity as relating to chemical structure. These rules were based on the more than 170 liquid crystal compounds he had synthesized in his lab. According to his rules, which later led to a statistical theoretical description of the behaviour of these materials, liquid crystalline states were formed by molecules with approximately linear shape. Vorlaender should also be remembered for his detection of polymorphism of the liquid crystal state, as he synthesized a liquid crystal compound with a nematic state and two smectic states. • George Freidel proposed a classification of liquid crystals based upon the different molecular orderings of each substance (nematic, smectic and cholesteric). He also explained the orienting effect of electric fields and the presence of defects in liquid crystals. 1922-39 Carl Oseen and Zöcher developed a mathematical basis for the study of liquid crystals and introduced the Order Parameter S to describe the averaged orientation of liquid crystals. Carl Oseen and F.C. Frank developed thecontinuum theory which was derived from Oseen’s work on elastic properties of liquid crystals.

  4. Silence 1939-45 World War II 1949 Onsager presented his work on the isotropic to nematic phase transition (Onsager-Theory). 1945-58 All was quiet on the liquid crystal front. People thought they knew everything about liquid crystals and that nothing new could be expected in this area. Even worse, they were not even included in textbooks. An entire decade of growing scientists did not have contact with liquid crystals

  5. The revival 1950s Work by Brown in the US, Chistiakoff in the Soviet Union, as well as Gray and Frank in England led to a revival of interest in liquid crystals. Frank and later Leslie and Ericksen developed continuum theories for static and dynamic systems. 1958 Alfred Saupe, later working at Kent State University, developed in his diploma thesis together with his advisor Wilhelm Maier a molecular theory of liquid crystals not involving permanent dipoles as Max Born's theory did. This work gave rise to the Maier-Saupe Theory, another well-known basic theory of liquid crystals. 1960s The first compound to exhibit a nematic phase at room temperature was the now famous MBBA. • Scientists from RCA demonstrated the first liquid crystal display (LCD). • The pure smectic C mesophase was discovered by Saupe.

  6. Interdisciplinary times 1974 W. MacMillan and R. Meyer proposed a mean-field theory for smectics. • Patricia Cladis observed a re-entrant nematic phase. Many theories have been suggested and demonstrated concerning this phenomenon. Perhaps the simplest and most clear is Pershen and Prost’s optimum density idea, which explains the existence of re-entrant phases in terms of molecular shape and interactions. • Bob Meyer suggested the possibility of ferroelectricity in liquid crystals and, following his idea, the chemists L. Liebert, L. Strzelecki, and P. Keller synthesized the first ferroelectric compound DOBAMBC. 1978 S. Chandrasekhar reported the existence of discotic liquid crystals. 1980 Yu and Saupe were the first to observe biaxiality in nematics.

  7. Becoming an exact science De Gennes expanded the Landau theory of phase transitions into liquid crystals. He was awarded the Nobel prize in 1991 for his contribution to the understanding of liquid crystals and polymers (soft matter physics). The Landau - de Gennes theory, which provides a phenomenological description of molecular order in various liquid crystal phases, transitions among them, and elastic and hydrodynamic properties, has proven to be extremely successful.

  8. First display applications 1960s RCA was first considering using liquid crystals for dynamic scattering displays but a room-temperature nematic liquid crystal did not exist. 1968 The first room-temperature nematic phase was observed by Demus in the compound MBBA but the temperature range was short and strongly affected by impurities. It was then discovered that eutectic mixtures of MBBA with other compounds in its homologous series could broaden the temperature range to extend from below -40 degrees centigrade to over 100 degrees centigrade. However, these mixtures were very unstable, and they also possessed a negative dielectric anisotropy not useful in the twist cell.

  9. A major breakthrough 1973 George W. Gray developed cyanobiphenyl materials that exhibit room-temperature nematic phases. These materials were not only more stable, but they also possessed a large positive dielectric anisotropy and strong birefringence nearly ideal for the twist cell, which had been invented only a few years earlier. Patents on these materials gave E. Merck of Darmstadt and F. Hoffmann-LaRoche, Ltd.of Basel a leading edge in the manufacturing and marketing of nematic materials for displays. The cyanobiphenyl patents expired around 1993 but both companies remain leading suppliers of today’s nematic materials and established divisions or joint ventures in Japan: Merck-Japan and RODIC. 1980 Noel Clark and S. Lagerwall patented a ferroelectric liquid crystal (FLC) display using chiral smectic C phases.

  10. Today’s display industry Nearly 50% of nematic materials supplied by Merck-Japan go toward twisted nematic (TN) displays, and another 10% toward TN active matrix (AM) displays. The latter type is expected to grow substantially in the next 10 years as the TN AM technology dominates the display manufacturing industry in Japan. Currently, the supertwisted nematic (STN) is a widely used display for laptop computers and consumes 40% of Merck-Japan nematic materials. Other display types, such as electrically controlled birefringence (ECB) or polymer-dispersed liquid crystals (PDLCs), currently consume only a small percentage of the nematic materials market. PDLC-type displays are a recent liquid crystal technology and have not yet reached much use in a commercial product. An interesting facet of the PDLC technology is its use in switchable windows.

  11. Recent Highlights Current devices suffer from three major limitations: restricted field of view, slow switching times for video applications, and sluggish response at low temperatures. Rolic's patented Deformed Helix Ferroelectric (DHF) technology addresses these problems so that DHF LCDs (molecular configuration provided below) can be used in various practical applications. These include color television projectors which have fast responding images, flat panel televisions, and navigation systems which exhibit fast response even at very low temperatures.

  12. Active-matrix display using ion-beam-processed polyimide film for liquid crystal alignment Ion-beam bombardment was developed as a substitute for mechanical rubbing of polyimide film as a noncontact liquid crystal (LC) alignment technique. The ion-beam technique was applied to a high-resolution thin-film-transistor-addressed liquid crystal display (TFT/LCD) panel. The results showed that LC alignment was achieved and that the display is capable of showing high-quality images. www.research.ibm.com

  13. Applications & Uses of LCs NLO Light Valves Spatial Light Modulators Photonics (optical switches) Molecular Actuators (artificial muscles) Spectroscopy Chromatography Chemical Reaction Media Visualization of Fields Temperature Defects (non destructive testing)

  14. Kevlar Optically Anisotropic Aromatic Polyamide Dopes and Oriented Fibers Therefrom Patent No. 3,819,587; re. 30,352,Inducted 1995 Stephanie Louise Kwolek’s research with high performance chemical compounds for the DuPont Company led to the development of a synthetic material called Kevlar which is five times stronger than the same weight of steel. Kevlar, patented by Kwolek in 1966, does not rust nor corrode and is extremely lightweight. Many police officers owe their lives to Stephanie Kwolek, for Kevlar is the material used in bullet proof vests. Other applications of the compound include underwater cables, brake linings, space vehicles, boats, parachutes, skis, and building materials.

  15. Other major areas of liquid crystal research Surfactants (Detergents, Soaps) Cleaning products, cosmetics, paper products, food products Biology, Membranes Synthetic membranes, micelles, and liposomes, L- and LB-films Phospholipid of cell membrane

  16. Centres of Liquid Crystal Research Liquid crystal centres:Bangalore – IndiaDisplay Industry – JapanHull – EnglandHalle – GermanyKent State – US Active scientific groups exist in:Europe (Russia, Poland, Germany, France, Italy, England, Spain)Asia (Japan, Korea, China)North America

  17. LC science in Canada Jacek Lipkowski, Chemistry, Guelph;Surface Analysis and Interfacial Electrochemistry, Adsorption of Insoluble Surfactants onto a Au(111)/electrolyte interface Derek G. Gray,Chemistry, McGill; Colloidal suspensions of cellulose crystallites, which form chiral nematic phases at low concentrations in water. Atomic force microscope to measure quantitatively the attractive and repulsive forces that operate between surfaces in water. These forces govern the stability of colloidal suspensions, including those of interest in papermaking. Linda Reven, Chemistry, McGill; NMR spectroscopy of organic monolayers, stabilized metal colloids, and more recently, of polyelectrolyte films. We use advanced solid-state NMR techniques in conjunction with transmission electron microscopy, vibrational spectroscopy and other surface science tools to study the surface and interfacial properties. M. Michel Pézolet and Mme Géraldine Bazuin, Chimie, Université Laval; Novel supramolecular liquid crystalline polymer materials Almeria Natansohn, Chemistry, Queens; Liquid crystalline polymers Robert P. Lemieux, Chemistry, Queens; Chiral induction in liquid crystal phases; The design of photochromic dopants for optical addressing of liquid crystal spatial light modulators; Molecular recognition in smectic liquid crystals Yue Zhao,Chimie, Sherbrooke, Liquid crystal gels for photonic materials; Self-assembling of functional materials; Liquid crystalline polymers Vance Williams, Chemistry, Simon Fraser; Discotic Liquid Crystals Dan Bizzotto,Chemistry, UBC;Adsorption of insoluble surfactants/lipids and proteins onto single crystal Au and Hg drop electrodes

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