History of Liquid Crystal Research
The first observations
1850
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.
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.
Early Foundations
1890
The first synthetic liquid crystal, p-azoxyanisole, was produced by
Gatterman and Ritschke.
MeO
N
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OMe
O
(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.
1922
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 the
continuum theory which was derived from Oseen’s work on elastic properties
of liquid crystals.
Silence
1939-45
1949
1945-58
World War II
Onsager presented his work on the isotropic to nematic phase
transition (Onsager-Theory).
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
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.
1968
Scientists from RCA demonstrated the first liquid crystal display
(LCD).
1969
The pure smectic C mesophase was discovered by Saupe.
Interdisciplinary times
1974
W. MacMillan and R. Meyer proposed a mean-field theory for
smectics.
1975
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 reentrant phases in terms of molecular shape and interactions.
1975
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.
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.
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.
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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.
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.
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.
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-filmtransistor-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
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)
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.
H
H
N
N
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n
Other major areas of liquid crystal research
Surfactants (Detergents, Soaps)
O
Cleaning products, cosmetics, paper
products, food products
S O- Na+
O
O
phosphate ester
+N
Biology, Membranes
P
O
O
O
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Synthetic membranes, micelles, amino-alcohol
OO
(Choline)
glycerol ester
O
and liposomes, L- and LB-films
Phospholipid of
cell membrane
Centres of Liquid Crystal Research
Liquid crystal centres:
Bangalore – India
Display Industry – Japan
Hull – England
Halle – Germany
Kent State – US
Active scientific groups exist in:
Europe (Russia, Poland,
Germany, France, Italy,
England, Spain)
Asia (Japan, Korea, China)
North America
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 solidstate 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; Selfassembling 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