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D. Demus, J. Goodby, G. W. Gray, H.-W. Spiess, V. Vill
Handbook of Liquid Crystals
Vol. 2 A: Low Molecular Weight Liquid Crystals I
@3 WILEY-VCH Weinheim New York Chichester Brisbane Singapore Toronto
This Page Intentionally Left Blank
Handbook of Liquid Crystals
D. Demus, J. Goodby, G. W. Gray, H.-W. Spiess, V. Vill
8 WILEY-VCH
Handbook of Liquid Crystals D. Demus, J. Goodby, Vol. 1:
Vol. 2 A: Low Molecular Weight Liquid Crystals I Vol. 2 B: Low Molecular Weight Liquid Crystals I1 VOl. 3: High Molecular Weight Liquid Crystals
G. W. Gray, Fundamentals H.-W. Spiess, V. Vill
Further title of interest: J. L. Serrano: Metallomesogens ISBN 3-527-29296-9
D. Demus, J. Goodby, G. W. Gray, H.-W. Spiess, V. Vill
Handbook of Liquid Crystals
Vol. 2 A: Low Molecular Weight Liquid Crystals I
@3 WILEY-VCH Weinheim New York Chichester Brisbane Singapore Toronto
Prof. Dietrich Demus Veilchenweg 23 06 1 18 Halle Germany
Prof. John W. Goodby School of Chemistry University of Hull Hull, HU6 7RX U. K.
Prof. George W. Gray Merck Ltd. Liquid Crystals Merck House Poole BH15 1TD U.K.
Prof. Hans-Wolfgang Spiess Max-Planck-Institut fur Polymerforschung Ackermannweg 10 55128 Mainz Germany
Dr. Volkmar Vill Institut fur Organische Chemie Universitat Hamburg Martin-Luther-King-Platz 6 20146 Hamburg Germany
This book was carefully produced. Nevertheless, authors, editors and publisher do not warrant the informa- tion contained therein to be free of errors. Readers are advised to keep in mind that statements, data, illus- trations, procedural details or other items may inadvertently be inaccurate.
Library of Congress Card No. applied for.
A catalogue record for this book is available from the British Library.
Deutsche Bibliothek Cataloguing-in-Publication Data:
Handbook of liquid crystals / D. Demus . . . - Weinheim ; New York ; Chichester ; Brisbane ; Singapore ; Toronto : Wiley-VCH
ISBN 3-527-29502-X Vol. 2A. Low molecular weight liquid crystals. - 1. - (1998) ISBN 3-527-29271-3
0 WILEY-VCH Verlag GmbH. D-60469 Weinheim (Federal Republic of Germany), 1998
Printed on acid-free and chlorine-free paper.
All rights reserved (including those of translation in other languages). No part of this book may be reproduced in any form -by photoprinting, microfilm, or any other means - nor transmitted or translated into machine lan- guage without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law. Composition and Printing: Fa. Konrad Triltsch Druck- und Verlagsanstalt GmbH, D-97070 Wiirzburg. Bookbinding: Wilhelm Osswald & Co., D-67433 Neustadt Printed in the Federal Republic of Germany.
The Editors
D. Demus studied chemistry at the Martin-Luther-University, Halle, Germany, where he was also awarded his Ph. D. In 1981 he became Professor, and in 1991 Deputy Vice-Chancellor of Halle University. From 1992-1994 he worked as a Special Technical Advisor for the Chisso Petrochemical Corporation in Japan. Throughout the period 1984-1991 he was a member of the International Planning and Steering Commi- tee of the International Liquid Crystal Conferences, and was a non-ex- ecutive director of the International Liquid Crystal Society. Since 1994 he is active as an Scientific Consultant in Halle. He has published over 310 scientific papers and 7 books and he holds 170 patients.
J. W. Goodby studied for his Ph. D. in chemistry under the guidance of G. W. Gray at the University of Hull, UK. After his post-doctoral research he be- came supervisor of the Liquid Crystal Device Materials Research Group at AT&T Bell Laboratories. In 1988 he returned to the UK to become the Thorn-EMUSTC Reader in Industrial Chemistry and in 1990 he was appointed Professor of Organic Chemistry and Head of the Liquid Crystal Group at the University of Hull. In 1996 he was the first winner of the G. W. Gray Medal of the British Liquid Crystal So- ciety.
G. W. Gray studied chemistry at the University of Glasgow, UK, and received his Ph. D. from the University of London before moving to the University of Hull. His contributions have been recognised by many awards and distinctions, including the Leverhulme Gold Medal of the Royal Soci- ety (l987), Commander of the Most Excellent Order of the British Em- pire ( 1 99 I ) , and Gold Medallist and Kyoto Prize Laureate in Advanced Technology ( 1995). His work on structure/property relationships has had far reaching influences on the understanding of liquid crystals and on their commercial applications in the field of electro-optical displays. In 1990 he became Research Coordinator for Merck (UK) Ltd, the com- pany which, as BDH Ltd, did so much to commercialise and market the electro-optic materials which he invented at Hull University. He is now active as a Consultant, as Editor of the journal “Liquid Crystals” and as authodeditor for a number of texts on Liquid Crystals.
VI The Editors
H. W. Spiess studied chemistry at the University of FrankfurUMain, Germany, and obtained his Ph. D. in physical chemistry for work on transition metal complexes in the group of H. Hartmann. After professorships at the University of Mainz, Munster and Bayreuth he was appointed Direc- tor of the newly founded Max-Planck-Institute for Polymer Research in Maim in 1984. His main research focuses on the structure and dy- namics of synthetic polymers and liquid crystalline polymers by ad- vanced NMR and other spectroscopic techniques.
V. Vill studied chemistry and physics at the University of Munster, Germany, and acquired his Ph. D. in carbohydrate chemistry in the gorup of J . Thiem in 1990. He is currently appointed at the University of Ham- burg, where he focuses his research on the synthesis of chiral liquid crystals from carbohydrates and the phase behavior of glycolipids. He is the founder of the LiqCryst database and author of the Landolt- Bornstein series Liquid Crystals.
List of Contributors
Volume 2A, Low Molecular Weight Crystals I
Bahadur, B. (III:3.3-3.4) Displays Center Rockwell Collins Inc. 400 Collins Road NE Ceder Rapids, IA 52498 USA
Blinc, R.; Musevic, I. (111:2.6) J. Stefan Institute University of Ljubljana Jamova 39 61 11 1 Ljubljana Slovenia
Booth, C. J. (IV: 1) Sharp Labs. of Europe Ltd. Edmund Halley Road Oxford Science Park Oxford OX4 4GA U.K.
Coates, D. (V:3) Merck Ltd. West Quay Road Poole, BH15 1HX U.K.
Coles, H. J. (IV:2) University of Southampton Dept. of Physics and Astronomy Liquid Crystal Group Highfield, Southampton SO17 1BJ U.K.
Goodby, J. W. (I and V: 1) School of Chemistry University of Hull Hull, HU6 7RX U.K.
Guillon, D. (11) IPCMS MatCriaux Organiques 23, rue de Loess 67037 Strasbourg Cedex France
Hirschmann, H.; Reiffenrath, V. (111:3.1) Merck KGaA LC FO/P Frankfurter StraBe 250 6427 1 Darmstadt Germany
Huang, C. C. (V:2) University of Minnesota Dept. of Physics Minneapolis, MN 55455 USA
Kaneko, E. (IIL3.2) Hitachi Research Laboratory Hitachi Ltd. 1 - 1, Ohmika, 7-chome Hi tac hi- s hi Ibaraki-ken, 3 19- 12 Japan
VIII List of Contributors
Kneppe, H.; Schneider, F. (111:2.5) Institut f. Physikal. Chemie Universitat Siegen 57068 Siegen Germany
Kresse, H. (IIk2.2) Martin-Luther-Universitat Halle- Wittenberg Fachbereich Chemie Institut f. Physikalische Chemie Muhlpforte 1 06108 Halle (Saale) Germany
Pelzl, G. (111:2.4) Fachbereich Chemie Institut f. Physikalische Chemie Muhlpforte 1 06108 Halle (Saale) Germany
Stannarius, R. (111:2.1 und 111:2.3) Universitat Leipzig LinnCstraBe 5 04 103 Leipzig Germany
Toyne, K. J. (111: 1) The University of Hull Liquid Crystals & Advanced Organic Materials Research Group Hull HU6 7RX U.K.
Outline
Volume 1
Chapter I: Introduction and Historical Development . . . . . . . . . . . . . . . . . . . 1 George W Gray
Chapter 11: Guide to the Nomenclature and Classification of Liquid Crystals . . . . . John W Goodby and George W Gray
17
Chapter 111: Theory of the Liquid Crystalline State . . . . . . . . . . . . . . . . . . . 25 Continuum Theory for Liquid Crystals . . . . . . . . . . . . . . . . . . . . 25 Frank M . Leslie Molecular Theories of Liquid Crystals . . . . . . . . . . . . . . . . . . . . 40 M. A. Osipov Molecular Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Mark R. Wilson
1
2
3
Chapter IV: General Synthetic Strategies . . . . . . . . . . . . . . . . . . . . . . . . 87 Thies Thiernann and Volkrnar Vill
Chapter V: Symmetry and Chirality in Liquid Crystals. . . . . . . . . . . . . . . . . 1 15 John W Goodby
Chapter VI: Chemical Structure and Mesogenic Properties . . . . . . . . . . . . . . 133 Dietrich Dernus
Chapter VII: Physical Properties . . . . . . . . . . . . . . . . , . . . . . . , . . , . 189 1 Tensor Properties of Anisotropic Materials . . . . . . . . . . . . . . . . . 189
David Dunrnur and Kazuhisa Toriyama 2 Magnetic Properties of Liquid Crystals . . . . . . . . . . . . . . . . . . . 204
David Dunmur and Kazuhisa Toriyama 3 Optical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 15
David Dunmur and Kazuhisa Toriyama 4 Dielectric Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1
David Dunrnur and Kazuhisa Toriyama 5 Elastic Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
David Dunrnur and Kazuhisa Toriyama 6 Phase Transitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 I
x Outline
6.1
6.2 6.2.1
6.2.2
6.2.3
6.2.4
6.3
6.4
7
8
9
10
11
12
13
Phase Transitions Theories . . . . . . . . . . . . . . . . . . . . . . . . . . 281 Philippe Barois Experimental Methods and Typical Results . . . . . . . . . . . . . . . . . 310 Thermal Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
Metabolemeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
High Pressure Investigations . . . . . . . . . . . . . . . . . . . . . . . . . 355
Fluctuations and Liquid Crystal Phase Transitions . . . . . . . . . . . . . 379
Re-entrant Phase Transitions in Liquid Crystals . . . . . . . . . . . . . . . 391
Defects and Textures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Flow Phenomena and Viscosity . . . . . . . . . . . . . . . . . . . . . . . 454
Behavior of Liquid Crystals in Electric and Magnetic Fields . . . . . . . . 477
Surface Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
Ultrasonic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
Jan Thoen
Wolfgang Wedler
Wolfgang Wedler
P. Pollrnann
P. E . Cladis
P. E . Cladis
Y. Bouligand
Frank Schneider and Herbert Kneppe
Lev M . Blinov
Blandine Je'rSme
Olga A . Kapustina Nonlinear Optical Properties of Liquid Crystals . . . . . . . . . . . . . . . 569 P. PalfSy-Muhoray
E Noack Diffusion in Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . 582
Chapter VIII: Characterization Methods . . . . . . . . . . . . . . . . . . . . . . . . 595 1 Magnetic Resonance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 595
X-Ray Characterization of Liquid Crystals: Instrumentation . . . . . . . . 619
Structural Studies of Liquid Crystals by X-ray Diffraction . . . . . . . . . 635
4 Neutron Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 680
Light Scattering from Liquid Crystals . . . . . . . . . . . . . . . . . . . . 699
Brillouin Scattering from Liquid Crystals . . . . . . . . . . . . . . . . . . 719
Mossbauer Studies of Liquid Crystals . . . . . . . . . . . . . . . . . . . . 727
Claudia Schmidt and Hans Wolfgang Spiess
Richard H . Templer
JohnM.Seddon
Robert M . Richardson
Helen E Gleeson
Helen E Gleeson
Helen E Gleeson
2
3
5
6
7
Outline XI
Chapter IX: Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731 I Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731
Nondisplay Applications of Liquid Crystals . . . . . . . . . . . . . . . . . 763
Thermography Using Liquid Crystals . . . . . . . . . . . . . . . . . . . . 823
Reaction. and Gas Chromatographic Applications
lun C . Sage
William A . Crossland and Timothy D . Wilkinson
Helen E Gleeson Liquid Crystals as Solvents for Spectroscopic. Chemical
William J . Leigh and Mark S . Workentin
2
3
4 . . . . . . . . . . . . . 839
Index Volume 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 897
Volume 2 A
Part I: Calamitic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter I: Phase Structures of Calamitic Liquid Crystals . . . . . . . . . . . . . . . . . 3
Chapter 11: Phase Transitions in Rod-Like Liquid Crystals . . . . . . . . . . . . . . . 23
John W Goodby
Daniel Guillon
Chapter 111: Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Synthesis of Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . 47
2 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Elastic Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . . . 60
Dielectric Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . . 91
Diamagnetic Properties of Nematic Liquid Crystals . . . . . . . . . . . . . 113
Optical Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . . 128
1 Kenneth J . Toyne
2.1
2.2
2.3
2.4
2.5 Viscosity 142
R a y Stannarius
Horst Kresse
R a y Stannarius
Gerhard Pelzl
Herbert Kneppe and Frank Schneider
R . Blinc and 1 . MuSevic'
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6 Dynamic Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . 170
TN, STN Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Active Matrix Addressed Displays . . . . . . . . . . . . . . . . . . . . . . 230
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Applications 199 3.1
3.2 Harald Hirschmann and Volker Reiffenrath
Eiji Kaneko
XI1 Outline
3.3
3.4
Dynamic Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Birendra Bahadur Guest-Host Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 Birendra Bahadur
Chapter IV: Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . 303 The Synthesis of Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . 303 Christopher J . Booth ChiralNematics: Physical Properties and Applications . . . . . . . . . . . 335 Harry Coles
1
2
Chapter V. Non-Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . . . . . . . 41 1 Synthesis of Non-Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . 41 1 John W. Goodby Physical Properties of Non-Chiral Srnectic Liquid Crystals. . . . . . . . . 441 C. C. Huang Nonchiral Smectic Liquid Crystals - Applications . . . . . . . . . . . . . 470 David Coates
1
2
3
Volume 2B
Part 2: Discotic Liquid Crystals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 1
Chapter VI: Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . 493 Synthesis of Chiral Smectic Liquid Crystals. . . . . . . . . . . . . . . . . 493 Stephen M. Kelly Ferroelectric Liquid Crystals. . . . . . . . . . . . . . . . . . . . . . . . . 515 Sven 7: Lagerwall Antiferroelectric Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . 665 Kouichi Miyachi and Atsuo Fukuda
1
2
3
Chapter VII: Synthesis and Structural Features, . . . . . . . . . . . . . . . . . . . . 693 Andrew N. Cammidge and Richard J. Bushby
Chapter VIII: Discotic Liquid Crystals: Their Structures and Physical Properties . . . 749 S. Chandrasekhar
Chapter IX: Applicable Properties of Columnar Discotic Liquid Crystals . . . . . . . 781 Neville Boden and Bijou Movaghar
Outline XI11
Part 3: Non-Conventional Liquid-Crystalline Materials . . . . . . . . . . . . . . . . 799
Chapter X: Liquid Crystal Dimers and Oligomers . . . . . . . . . . . . . . . . . . . 801 Corrie 7: Irnrie and Geoffrey R . Luckhurst
Chapter XI: Laterally Substituted and Swallow-Tailed Liquid Crystals . . . . . . . . 835 Wolfgang Weissflog
Chapter XII: Phasmids and Polycatenar Mesogens . . . . . . . . . . . . . . . . . . . 865 Huu-Tinh Nguyen. Christian Destrade. and Jacques MalthZte
Chapter XIII: Thermotropic Cubic Phases . . . . . . . . . . . . . . . . . . . . . . . 887 Siegmar Diele and Petra Goring
Chapter XIV: Metal-containing Liquid Crystals . . . . . . . . . . . . . . . . . . . . 901 Anne Marie Giroud-Godquin
Chapter XV: Biaxial Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . 933 B . K. Sadashiva
Chapter XVI: Charge-Transfer Systems . . . . . . . . . . . . . . . . . . . . . . . . 945 Klaus Praefcke and D . Singer
Chapter XVII: Hydrogen-Bonded Systems . . . . . . . . . . . . . . . . . . . . . . . 969 Takashi Kato
Chapter XVIII: Chromonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 981 John Lydon
Index Volumes 2A and 2 B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1009
Volume 3
Part 1 : Main-Chain Thermotropic Liquid-Crystalline Polymers . . . . . . . . . . . . . 1
Chapter I: Synthesis. Structure and Properties . . . . . . . . . . . . . . . . . . . . . . 3 Aromatic Main Chain Liquid Crystalline Polymers . . . . . . . . . . . . . . 3 Andreas Greiner and Hans- Werner Schmidt
Emo Chiellini and Michele Laus
Rudolf Zentel
Guoping Ma0 and Christopher K . Ober
1
2
3
4
Main Chain Liquid Crystalline Semiflexible Polymers . . . . . . . . . . . . 26
Combined Liquid Crystalline Main-Chain/Side-Chain Polymers . . . . . . . 52
Block Copolymers Containing Liquid Crystalline Segments . . . . . . . . . 66
XIV Outline
Chapter 11: Defects and Textures in Nematic Main-Chain Liquid
Claudine Noel
Crystalline Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Part 2: Side-Group Thermotropic Liquid-Crystalline Polymers . . . . . . . . . . . . 121
Chapter 111: Molecular Engineering of Side Chain Liquid Crystalline
Coleen Pugh and Alan L. Kiste Polymers by Living Polymerizations . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Chapter IV: Behavior and Properties of Side Group Thermotropic Liquid
Jean-Claude Dubois, Pierre Le Barny, Monique Mauzac, and Claudine Noel Crystal Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Chapter V: Physical Properties of Liquid Crystalline Elastomers . . . . . . . . . . . 277 Helmut R. Brand and Heino Finkelmann
Part 3: Amphiphilic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Chapter VI: Amphotropic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . 305 Dieter Blunk, Klaus Praefcke and Volkmar Vill
Chapter VII: Lyotropic Surfactant Liquid Crystals . . . . . . . . . . . . . . . . . . . 341 C. Fairhurst, S. Fuller, J . Gray, M. C. Holmes, G. J. 7: Tiddy
Chapter VIII: Living Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393 Siegfried H o f i a n n
Chapter IX: Cellulosic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . 45 1 Peter Zugenmaier
Index Volumes 1 - 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
Contents
Volume 2 A
Part I: Calamitic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . i
Chapter I: Phase Structures of Calamitic Liquid Crystals . . . . . . . . . . . . . . 3 John W Goodby
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Melting Processes of Calamitic Thermotropic Liquid Crystals . . . . . . . . . 4
3 3.1 3.2 3.3 3.3. I 3.3.2 3.3.3 3.3.4 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5
Structures of Calamitic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . 6 The Nematic Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Structures of Smectic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . 7 The Structures of the Orthogonal Smectic Phases . . . . . . . . . . . . . . . 7 Structure of the Smectic A Phase . . . . . . . . . . . . . . . . . . . . . . . . 7 Structure in the Hexatic B Phase . . . . . . . . . . . . . . . . . . . . . . . . 10 Structure of the Crystal B Phase . . . . . . . . . . . . . . . . . . . . . . . . 10 Structure of Crystal E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Structures of the Tilted Smectic Phases . . . . . . . . . . . . . . . . . . . . . 13 Structure of the Smectic C Phase . . . . . . . . . . . . . . . . . . . . . . . . 13 Structure of the Smectic I Phase . . . . . . . . . . . . . . . . . . . . . . . . 16 Structure of the Smectic F Phase 16 Structures of the Crystal J and G Phases . . . . . . . . . . . . . . . . . . . . 17 Structures of the Crystal H and K Phases . . . . . . . . . . . . . . . . . . . . 18
. . . . . . . . . . . . . . . . . . . . . . . .
4
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 20
Long- and Short-Range Order . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Chapter 11: Phase Transitions in Rod-Like Liquid Crystals . . . . . . . . . . . . . 23
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2 Isotropic-Nematic (Iso-N) Transition . . . . . . . . . . . . . . . . . . . . . 23 Brief Summary of the Landau-de Gennes Model . . . . . . . . . . . . . . . . 23
2.2 Magnetic Birefringence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.3 Light Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Deviations from the Landau-de Gennes Model . . . . . . . . . . . . . . . . . 25
Daniel Guillon
2.1
2.4
XVI Contents
3 3.1 3.2
4 4.1 4.2 4.3 4.4 4.5 4.6
5 5.1 5.2
6 6.1 6.2 6.3
7 7.1 7.2 7.3 7.4
8
Nematic-Smectic A (N-SmA) Transition . . . . . . . . . . . . . . . . . . . . 26 The McMillan-de Gennes Approach . . . . . . . . . . . . . . . . . . . . . . 26 Critical Phenomena: Experimental Situation . . . . . . . . . . . . . . . . . . 26
Smectic A-Smectic C (SmA-SmC) Transition . . . . . . . . . . . . . . . . . 29 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Critical Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Experimental Situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Smectic A-Smectic C* (SmA-SmC*) Transition . . . . . . . . . . . . . . . . 32 The Nematic-Smectic A-Smectic C (NAC) Multicritical Point . . . . . . . . 33 SmA-SmC Transition in Thin Films . . . . . . . . . . . . . . . . . . . . . . 35
Hexatic B to Smectic A (SmBhex-SmA) transition . . . . . . . . . . . . . . 36 General Presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 SmBhex-SmA Transition in Thin Films . . . . . . . . . . . . . . . . . . . . 37
Induced Phase Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Mechanically Induced SmA-SmC Transition . . . . . . . . . . . . . . . . . . 38 Electrically Induced Transitions . . . . . . . . . . . . . . . . . . . . . . . . 39 Photochemically Induced Transitions . . . . . . . . . . . . . . . . . . . . . . 39
Other Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Smectic C to Smectic I (SmC-SmI) Transition . . . . . . . . . . . . . . . . . 41 Smectic C to Smectic F (SmC-SmF) Transition . . . . . . . . . . . . . . . . 41 Smectic F to Smectic I (SmF-SmI) Transition . . . . . . . . . . . . . . . . . 42
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Smectic F to Smectic Crystalline G (SmF-SmG) Transition . . . . . . . . . . 42
Chapter 111: Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . 47
1
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12
Synthesis of Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . 47
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Benzene. Biphenyl and Terphenyl Systems . . . . . . . . . . . . . . . . . . . 48 Cyclohexane Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 1,4-Disubstituted-bicyclo[2.2.2]octanes . . . . . . . . . . . . . . . . . . . . 50 2,5.Disubstituted.l. 3.dioxanes . . . . . . . . . . . . . . . . . . . . . . . . . 51 2,5.Disubstitute d.pyridines . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 2.5.Disubstituted.pyrimidines . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3,6.Disubstituted.pyridazines . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Naphthalene systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Unusual Core Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Ester Linkages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Lateral Substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Kenneth J . Toyne
Contents XVII
1.13
1.15 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4-c-(trans-4-Alkylcyclohexyl)- 1 -alkyl-r- 1 .cyanocyclohexanes . . . . . . . . . 55 1.14 Terminal Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2 2.1
2.1.1 2.1.2 2.1.2.1 2.1.2.2 2.1.2.3 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.1.8
2.2
2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6
Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Elastic Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . . . . 60
Ralf Stannarius Introduction to Elastic Theory . . . . . . . . . . . . . . . . . . . . . . . . . 60 Measurement of Elastic Constants . . . . . . . . . . . . . . . . . . . . . . . 63 Frkedericksz Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Light Scattering Measurements . . . . . . . . . . . . . . . . . . . . . . . . . 68 Other Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Experimental Elastic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
‘Surface-like’ Elastic Constants . . . . . . . . . . . . . . . . . . . . . . . . . 73 Theory of Elastic Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Biaxial Nematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
MBBA and n-CB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Dielectric Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . . . 91
Rod-like Molecules in the Isotopic State . . . . . . . . . . . . . . . . . . . . 91 Static Dielectric Constants of Nematic Samples . . . . . . . . . . . . . . . . 92 The Nre Phenomenon and the Dipolar Correlation . . . . . . . . . . . . . . . 98 Dielectric Relaxation in Nematic Phases . . . . . . . . . . . . . . . . . . . . 99 Dielectric Behavior of Nematic Mixtures . . . . . . . . . . . . . . . . . . . 102 References 109
Horst Kresse
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Diamagnetic Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . 113
2.3.1 Magnetic Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 2.3.2 Measurement of Diamagnetic Properties . . . . . . . . . . . . . . . . . . . 116 2.3.2.1 Faraday-Curie Balance Method . . . . . . . . . . . . . . . . . . . . . . . . 116 2.3.2.2 Supraconducting Quantum Interference Devices Measurements . . . . . . . 116 2.3.2.3 NMR Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 2.3.2.4 Magneto-electric Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 2.3.2.5 Mechanical Torque Measurements . . . . . . . . . . . . . . . . . . . . . . . 118 2.3.3 Experimental Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Increment System for Diamagnetic Anisotropies . . . . . . . . . . . . . . . 124 Application of Diamagnetic Properties . . . . . . . . . . . . . . . . . . . . 125
Optical Properties of Nematic Liquid Crystals . . . . . . . . . . . . . . . . 128
2.4.2 Experimental Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Ralf Stannarius
118
2.3.4 2.3.5 2.3.6 References 126
2.4
2.4.1 Introduction 128
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gerhard Pelzl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XVIII Contents
2.4.3 2.4.4 2.4.5
2.4.7
2.4.8
Temperature Dependence of Birefringence and Refractive Indices . . . . . . 132 Dispersion of ne. no and An . . . . . . . . . . . . . . . . . . . . . . . . . . 133
2.4.6 Birefringence in Homologous Series . . . . . . . . . . . . . . . . . . . . . 136
Order from Birefringence Data . . . . . . . . . . . . . . . . . . . . . . . . 136 Relationships between Birefringence and Molecular Structure . . . . . . . . 137
2.4.9 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Refractive Indices of Mixtures . . . . . . . . . . . . . . . . . . . . . . . . . 135
Determination of Molecular Polarizability Anisotropy and Orientational
2.5 Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
2.5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Determination of Shear Viscosity Coefficients . . . . . . . . . . . . . . . . 142
2.5.2.1 General Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 2.5.2.2 Mechanical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 2.5.2.3 Light Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 2.5.2.4 Other Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 2.5.2.5 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Determination of Rotational Viscosity . . . . . . . . . . . . . . . . . . . . . 155 2.5.3.1 General Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 2.5.3.2 Experimental Methods with Permanent Director Rotation . . . . . . . . . . 156 2.5.3.3 Relaxation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 2.5.3.4 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 2.5.4 Leslie Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Determination from Shear and Rotational Viscosity Coefficients . . . . . . . 165 2.5.4.2 Determination by Means of Light Scattering . . . . . . . . . . . . . . . . . 166 2.5.4.3 Other Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 2.5.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Herbert Kneppe and Frank Schneider
2.5.2
2.5.3
2.5.4.1
2.6
2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.6.6 2.6.7 2.6.8 2.6.9 2.6.10 2.6.11 2.6.12 2.6.13 2.6.14
Dynamic Properties of Nematic Liquid Crystals
Quasielastic Light Scattering in Nematics . . . . . . . . . . . . . . . . . . . 170 Nuclear Magnetic Resonance in Nematics . . . . . . . . . . . . . . . . . . . 173
Quasielastic Light Scattering and Orientational Fluctuations below Tc Nuclear Magnetic Resonance and Orientational Fluctuations below Tc . . . . 177
Pretransitional Dynamics Near the Nematic-Smectic A Transition . . . . . . 183 Dynamics of Nematics in Micro-Droplets and Micro-Cylinders . . . . . . . 184 Pretransitional Effects in Confined Geometry . . . . . . . . . . . . . . . . . Dynamics of Randomly Constrained Nematics . . . . . . . . . . . . . . . . 189 Other Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
. . . . . . . . . . . . . . . 170 R . Blinc and I . MuSevic'
Quasielectric Light Scattering and Order Fluctuations in the Isotropic Phase 174 Nuclear Magnetic Resonance and Order Fluctuations in the Isotropic Phase . 175
177
Optical Ken Effect and Transient Laser-Induced Molecular Reorientation . . 18 1 Dielectric Relaxation in Nematics . . . . . . . . . . . . . . . . . . . . . . . 182
. . .
188
Contents XIX
3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 3.1 TN. STN Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
3.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 3.1.2 Twisted Nematic Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 3.1.2.1 Configuration and Operation Principles of Twisted Nematic Displays . . . . 200 3.1.2.2 Optical Properties of the Unactivated State . . . . . . . . . . . . . . . . . . 200 3.1.2.3 Optical Properties of the Activated State . . . . . . . . . . . . . . . . . . . 202 3.1.3 Addressing of Liquid Crystal Displays . . . . . . . . . . . . . . . . . . . . 204 3.1.3.1 Direct Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 3.1.3.2 Passive Matrix Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 3.1.3.3 The Improved Alt-Pleshko Addressing Technique 3.1.3.4 Generation of Gray Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 3.1.4 Supertwisted Nematic Displays . . . . . . . . . . . . . . . . . . . . . . . . 208 3.1.4.1 Influence of Device and Material Parameters . . . . . . . . . . . . . . . . . 208 3.1.4.2 Configuration and Transmission of a Supertwisted Nematic Display . . . . . 211 3.1.4.3 Electro-optical Performance of Supertwisted Nematic Displays . . . . . . . 213 3.1.4.4 Dynamical Behavior of Twisted Nematic and Supertwisted Nematic Displays 2 13 3.1.4.5 Color Compensation of STN Displays . . . . . . . . . . . . . . . . . . . . . 215 3.1.4.6 Viewing Angle and Brightness Enhancement . . . . . . . . . . . . . . . . . 218 3.1.4.7 Color Supertwisted Nematic Displays . . . . . . . . . . . . . . . . . . . . . 218 3.1.4.8 Fast Responding Supertwisted Nematic Liquid Crystal Displays . . . . . . . 219
Display Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Materials with High Optimal Anisotropy . . . . . . . . . . . . . . . . . . . 221 Materials with Positive Dielectric Anisotropy . . . . . . . . . . . . . . . . . 221
3.1.5.3 Materials for the Adjustment of the Elastic Constant Ratio K33/Kll . . . . 225 Dielectric Neutral Basic Materials . . . . . . . . . . . . . . . . . . . . . . . 226
Harald Hirschmann and Volker Reiffenrath
. . . . . . . . . . . . . . 207
3.1 . 5
3.1.5.1 3.1 S . 2
3.1.5.4 3.1.6 References 227
Liquid Crystal Materials for Twisted Nematic and Supertwisted Nematic
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Active Matrix Addressed Displays . . . . . . . . . . . . . . . . . . . . . . 230
3.2.1 Thin Film Diode and Metal-Insulator-Metal Matrix Address . . . . . . . . . 230 3.2.1.1 Diode Ring Matrix Address . . . . . . . . . . . . . . . . . . . . . . . . . . 230 3.2.1.2 Back-to-back Diode Matrix Address . . . . . . . . . . . . . . . . . . . . . . 230 3.2.1.3 Two Branch Diode Matrix Address . . . . . . . . . . . . . . . . . . . . . . 231 3.2.1.4 SiNx Thin Film Diode Matrix Address . . . . . . . . . . . . . . . . . . . . 231 3.2.1.5 Metal-Insulator-Metal Matrix Address . . . . . . . . . . . . . . . . . . . . 232 3.2.2 CdSe Thin Film Transistor Switch Matrix Address . . . . . . . . . . . . . . 233 3.2.3 a-Si Thin Film Transistor Switch Matrix Address . . . . . . . . . . . . . . . 234 3.2.4 p-Si Thin Film Transistor Switch Matrix Address . . . . . . . . . . . . . . . 237 3.2.4.1 Solid Phase Crystallization Method . . . . . . . . . . . . . . . . . . . . . . 238 3.2.4.2 Laser Recrystallization Method . . . . . . . . . . . . . . . . . . . . . . . . 238 3.2.5 Metal-oxide Semiconductor Transistor Switch Matrix Address . . . . . . . . 239 3.2.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Eiji Kaneko
xx Contents
3.3 Dynamic Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Introduction and Cell Designing . . . . . . . . . . . . . . . . . . . . . . . . 243
(Alternating Current) Fields . . . . . . . . . . . . . . . . . . . . . . . . . . 244 Homogeneously Aligned Nematic Regime . . . . . . . . . . . . . . . . . . 244
3.3.2.2 Williams Domains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 3.3.2.3 Dynamic Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 3.3.3 Observations at High Frequency AC Field . . . . . . . . . . . . . . . . . . 247 3.3.4 Theoretical Explanations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 3.3.4.1 Carr-Helfrich Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 3.3.4.2 Dubois-Violette, de Gennes, and Parodi Model . . . . . . . . . . . . . . . . 249
Dynamic Scattering in Smectic A and Cholesteric Phases 3.3.6 Electrooptical Characteristics and Limitations . . . . . . . . . . . . . . . . 251
and Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 3.3.6.2 Display Current Versus Voltage, Cell Gap, and Temperature . . . . . . . . . 252 3.3.6.3 Switching Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 3.3.6.4 Effect of Conductivity, Temperature and Frequency . . . . . . . . . . . . . 253 3.3.6.5 Addressing of DSM (Dynamic Scattering Mode) LCDs
(Liquid Crystal Displays) . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 3.3.6.6 Limitations of DSM LCDs . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 3.3.7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Birendra Bahadur
Experimental Observations at DC (Direct Current) and Low Frequency AC 3.3.1 3.3.2
3.3.2.1
3.3.5
3.3.6.1 Contrast Ratio Versus Voltage, Viewing Angle, Cell Gap, Wavelength,
. . . . . . . . . . 250
3.4 Guest-Host Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
3.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 3.4.2 Dichroic Dyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 3.4.2.1 Chemical Structure, Photostability, and Molecular Engineering . . . . . . . 260 3.4.3 Cell Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 3.4.4 Dichroic Parameters and Their Measurement . . . . . . . . . . . . . . . . . 268 3.4.4.1 Order Parameter and Dichroic Ratio of Dyes . . . . . . . . . . . . . . . . . 268 3.4.4.2 Absorbance, Order Parameter, and Dichroic Ratio Measurement . . . . . . . 269 3.4.5 Impact of Dye Structure and Liquid Crystal Host on the Physical Properties
of a Dichroic Mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 3.4.6 Optical, Electro-Optical, and Life Parameters . . . . . . . . . . . . . . . . . 271 3.4.6.1 Luminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272 3.4.6.2 Contrast and Contrast Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . 272 3.4.6.3 Switching Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 3.4.6.4 Life Parameters and Failure Modes . . . . . . . . . . . . . . . . . . . . . . 273 3.4.7 Dichroic Mixture Formulation . . . . . . . . . . . . . . . . . . . . . . . . . 274 3.4.7.1 Monochrome Mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 3.4.7.2 Black Mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 3.4.8 Heilmeier Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 3.4.8.1 Threshold Characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Birendra Bahadur
Contents XXI
3.4.8.2 Effects of Dye Concentration on Electro-optical Parameters . . . . . . . . . 276 3.4.8.3 Effect of Cholesteric Doping . . . . . . . . . . . . . . . . . . . . . . . . . . 278 3.4.8.4 Effect of Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 3.4.8.5 Effect of Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 3.4.8.6 Impact of the Order Parameter . . . . . . . . . . . . . . . . . . . . . . . . . 279 3.4.8.7 Impact of the Host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Impact of the Polarizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 3.4.8.9 Color Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 3.4.8.10 Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
Quarter Wave Plate Dichroic Displays . . . . . . . . . . . . . . . . . . . . . 282 Dye-doped TN Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
3.4.11 Phase Change Effect Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . 284 3.4.11.1 Threshold Characteristic and Operating Voltage . . . . . . . . . . . . . . . . 286
3.4.1 1.3 Memory or Reminiscent Contrast . . . . . . . . . . . . . . . . . . . . . . . 289 3.4.1 1.4 Electro-optical Performance vs Temperature . . . . . . . . . . . . . . . . . 291 3.4.11.5 Multiplexing Phase Change Dichroic LCDs . . . . . . . . . . . . . . . . . . 291 3.4.12 Double Cell Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . . . . . . 291 3.4.12.1 Double Cell Nematic Dichroic LCD . . . . . . . . . . . . . . . . . . . . . . 291 3.4.12.2 Double Cell One Pitch Cholesteric LCD . . . . . . . . . . . . . . . . . . . 292 3.4.12.3 Double Cell Phase Change Dichroic LCD . . . . . . . . . . . . . . . . . . . 292 3.4.13 Positive Mode Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . . . . . 292 3.4.13.1 Positive Mode Heilmeier Cells . . . . . . . . . . . . . . . . . . . . . . . . 292 3.4.13.2 Positive Mode Dichroic LCDs Using a a 4 Plate . . . . . . . . . . . . . . . 295 3.4.13.3 Positive Mode Double Cell Dichroic LCD . . . . . . . . . . . . . . . . . . 29.5 3.4.13.4 Positive Mode Dichroic LCDs Using Special Electrode Patterns . . . . . . . 295 3.4.13.5 Positive Mode Phase Change Dichroic LCDs . . . . . . . . . . . . . . . . . 295 3.4.13.6 Dichroic LCDs Using an Admixture of Pleochroic
and Negative Dichroic Dyes . . . . . . . . . . . . . . . . . . . . . . . . . . 296 3.4.14 Supertwist Dichroic Effect Displays . . . . . . . . . . . . . . . . . . . . . . 296 3.4.1.5 Ferroelectric Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . . . . . . 296 3.4.15.1 Devices Using A Single Polarizer . . . . . . . . . . . . . . . . . . . . . . . 297 3.4.15.2 Devices Using No Polarizers . . . . . . . . . . . . . . . . . . . . . . . . . 297 3.4.16 Polymer Dispersed Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . . 297 3.4.17 Dichroic Polymer LCDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 3.4.18 Smectic A Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 3.4.19 Fluorescence Dichroic LCDs . . . . . . . . . . . . . . . . . . . . . . . . . 299 3.4.20 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
3.4.8.8
3.4.9 3.4.10
3.4.1 1.2 Contrast Ratio, Transmission Brightness, and Switching Speed . . . . . . . . 287
Chapter I V Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . 303
1
1.1
The Synthesis of Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . . 303
Introduction to the Chiral Nematic Phase and its Properties Christopher J . Booth
. . . . . . . . . 303
XXII Contents
1.2 1.3 1.3.1 1.4 1.5 1.5.1 1.5.2 1.5.3 1.5.4 1.5.5 1.6 1.6.1 1.6.2
1.6.3 1.7 1.7.1 1.7.2 1.7.3 1.74 1.8 1.9
Formulation and Applications of Thermochromic Mixtures . . . . . . . . . . 305 Classification of Chiral Nematic Liquid Crystalline Compounds . . . . . . . 307 Aspects of Molecular Symmetry for Chiral Nematic Phases . . . . . . . . . 308 Cholesteryl and Related Esters . . . . . . . . . . . . . . . . . . . . . . . . . 310 Type I Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . 311 Azobenzenes and Related Mesogens . . . . . . . . . . . . . . . . . . . . . 312 Azomethine (Schiff’s Base) Mesogens . . . . . . . . . . . . . . . . . . . . 313 Stable Phenyl. Biphenyl. Terphenyl and Phenylethylbiphenyl Mesogens . . . 3 14 (R)-2-(4-Hydroxyphenoxy)-propanoic Acid Derivatives . . . . . . . . . . . 319 Miscellaneous Type I Chiral Nematic Liquid Crystals . . . . . . . . . . . . 323 Type I1 Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . 325 Azomethine Ester Derivatives of (R)-3-Methyladipic Acid . . . . . . . . . . 325
of (R)-3-Methyladipic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . 326 Chiral Dimeric Mesogens Derived from Lactic Acid or 1. 2.Diols . . . . . . 327 Type I11 Chiral Nematic Liquid Crystals . . . . . . . . . . . . . . . . . . . . 327 Tricyclo[4.4.0.03,8]decane or Twistane Derived Mesogens . . . . . . . . . . 328 Axially Chiral Cyclohexylidene-ethanones . . . . . . . . . . . . . . . . . . 328 Chiral Heterocyclic Mesogens . . . . . . . . . . . . . . . . . . . . . . . . . 330 Chiral Mesogens Derived from Cyclohexane . . . . . . . . . . . . . . . . . 331 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Novel Highly Twisting Phenyl and 2-Pyrimidinylphenyl Esters
2 Chiral Nematics: Physical Properties and Applications . . . . . . . . . . . . 335
2.1 Introduction to Chiral Nematics: General Properties . . . . . . . . . . . . . 335 2.2 Static Properties of Chiral Nematics . . . . . . . . . . . . . . . . . . . . . . 342 2.2.1 Optical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 2.2.1.1 Textures and Defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 2.2.1.2 Optical Propagation (Wave Equation Approach) . . . . . . . . . . . . . . . 356 2.2.1.3 Optical Propagation (‘Bragg’ Reflection Approach) . . . . . . . . . . . . . 362 2.2.1.4 Pitch Behavior as a Function of Temperature, Pressure, and Composition . . 365 2.2.2 Elastic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 2.2.2.1 Continuum Theory and Free Energy . . . . . . . . . . . . . . . . . . . . . . 369 2.3 Dynamic Properties of Chiral Nematics . . . . . . . . . . . . . . . . . . . . 374 2.3.1 Viscosity Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374 2.3.2 Lehmann Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377 2.3.3 Macroscopic Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
Field-Induced Distortions in Chiral Nematics . . . . . . . . . . . . . . . . . 382 2.4.1 Magnetic Fields Parallel to the Helix Axis . . . . . . . . . . . . . . . . . . 382 2.4.2 Magnetic Fields Normal to the Helix Axis . . . . . . . . . . . . . . . . . . 386 2.4.3 Electric Fields Parallel to the Helix Axis . . . . . . . . . . . . . . . . . . . 388 2.4.4 Electric Fields Normal to the Helix Axis . . . . . . . . . . . . . . . . . . . 391 2.5 Applications of Chiral Nematics . . . . . . . . . . . . . . . . . . . . . . . . 394 2.5.1 Optical: Linear and Nonlinear . . . . . . . . . . . . . . . . . . . . . . . . . 394
Harry Coles
2.4
Contents XXIII
2.5.2 Thermal Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 2.5.3 External Electric Field Effects . . . . . . . . . . . . . . . . . . . . . . . . . 399 2.5.3.1 Long Pitch Systems @>>A) . . . . . . . . . . . . . . . . . . . . . . . . . . 400 2.5.3.2 Intermediate Pitch Length Systems @ = A ) . . . . . . . . . . . . . . . . . . . 401 2.5.3.3 Short Pitch Systems ( p e a ) . . . . . . . . . . . . . . . . . . . . . . . . . . 403 2.6 Conclusions and the Future . . . . . . . . . . . . . . . . . . . . . . . . . . 404 2.7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Chapter V Non-Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . . . . . 411
1
1 .1 1.2 I . 2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.3 1.3.1
1.3.2
1.3.3
1.3.4
1.3.5 1.3.6
1.3.7
1.3.8
1.3.9
1.3.10
1.4 1.4.1
Synthesis of Non-Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . . 411 John W Goodby Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411 Template Structures for the Synthesis of Smectogens . . . . . . . . . . . . . 411 Terminal Aliphatic Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . 414 Polar Groups Situated at the End of the Core . . . . . . . . . . . . . . . . . 415 Functional Groups that Terminate the Core Structure . . . . . . . . . . . . . 417 Core Ring Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418 Liking Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 Lateral Substitutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422 Syntheses of Standard Smectic Liquid Crystals . . . . . . . . . . . . . . . . 426 Synthesis of 4-Alkyl- and 4-alkoxy-4‘-cyanophenyls: Interdigitated Smectic A Materials (e.g., 8CB and (80CB) . . . . . . . . . . . . . . . . . 426 Synthesis of 4-Alkyl-4-alkoxybiphenyl-4’-carboxylates: Hexatic Smectic B Materials (e.g., 650BC) . . . . . . . . . . . . . . . . . . . . . . 427 Synthesis of 4-Alkyloxy-benzylidene-4-alkylanilines: Crystal B and G Materials (e.g., nOms) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428 Synthesis of Terephthalylidene-bis-4-alkylanilines: Smectic I. Smectic F. Crystal G and Crystal H Materials (e.g., TBnAs) . . . . . . . . . . . . . . . 428 Synthesis of 4-Alkoxy-phenyl-4-alkoxybenzoates: Smectic C Materials . . . 429 Synthesis of 4-Alkylphenyl-4-alkylbiphenyl-4’-carboxylates: Smectic C. Smectic I. Hexatic Smectic B Materials . . . . . . . . . . . . . . . . . . . . 430 Synthesis of 4-(2-Methylutyl)phenyl-4-alkoxybiphenyl-4’-carboxylates: Smectic C. Smectic I. Smectic F. Crystal J. Crystal K and Crystal G Materials (nOmIs. e.g., 80SI) . . . . . . . . . . . . . . . . . . . . . . . . . 430 Synthesis of 2-(4-n-Alkylphenyl)-5-(4-n-alkoxyoxyphenyl)pyrimidines: Smectic F and Crystal G Materials . . . . . . . . . . . . . . . . . . . . . . 431 Synthesis of 3-Nitro- and 3-Cyano-4-n-alkoxybiphenyl-4’-carboxylic Acids: Cubic and Smectic C Materials . . . . . . . . . . . . . . . . . . . . 433 Synthesis of bis-[ 1 -(4’-Alkylbiphenyl-4-y1) -3-(4-alkylphenyl)propane- 1. 3-dionato]copper(lI). Smectic Metallomesogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 Synthesis of Smectic Materials for Applications Synthesis of Ferroelectric Host Materials . . . . . . . . . . . . . . . . . . . 435
. . . . . . . . . . . . . . . 435
XXIV Contents
. 4.2 Synthesis of Antiferroelectric Host Materials . . . . . . . . . . . . . . . . . 437
. 5 Summary 438
. 6 References 439 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2.1 2.2 2.2.1 2.2.2 2.3 2.3.1 2.3.2 2.4 2.4.1 2.4.1.1 2.4.2 2.4.2.1 2.5 2.5.1 2.5.2 2.5.3 2.6 2.7
Physical Properties of Non-Chiral Smectic Liquid Crystals . . . . . . . . . . 441
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 Smectic A Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443 Macroscopic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443 X-ray Characterization of Free-Standing Smectic Films . . . . . . . . . . . 446 Hexatic Smectic B Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . 447 Macroscopic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448 Thin Hexatic B Films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450 Smectic C Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 Physical Properties near the Smectic A-Smectic C Transition . . . . . . . . 452 Bulk Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 Macroscopic Behavior of the Smectic C Phase . . . . . . . . . . . . . . . . 457 Bulk Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457 Tilted Hexatic Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 Identification of Hexatic Order in Thin Films . . . . . . . . . . . . . . . . . 461 Characterization of Hexatic Order in Thick Films . . . . . . . . . . . . . . . 462 Elastic Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464 Surface Tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
C . C . Huang
3 Nonchiral Smectic Liquid Crystals . Applications . . . . . . . . . . . . . . 470
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 470 3.2 Smectic Mesogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471 3.3 Laser-Addressed Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . 473 3.3.1 Basic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473 3.3.1.1 Normal Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473 3.3.1.2 Reverse Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475 3.3.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 3.3.2.1 Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 3.3.2.2 Lasers and Dyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 3.3.2.3 Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477 3.3.3 Physical Characteristics and Applications . . . . . . . . . . . . . . . . . . . 478 3.3.3.1 Line Width and Write Speed . . . . . . . . . . . . . . . . . . . . . . . . . . 478 3.3.3.2 Contrast Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478 3.3.3.3 Projection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478 3.3.3.4 Color Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478 3.3.3.5 Commercial Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478
Thermally and Electrically Addressed Displays . . . . . . . . . . . . . . . . 481 Dielectric Reorientation of SmA Phases . . . . . . . . . . . . . . . . . . . . 482
3.5.1 Materials of Negative Dielectric Anisotropy . . . . . . . . . . . . . . . . . 482
David Coates
3.4 3.5
Contents xxv
3.5.2 3.5.3 3.6 3.6.1 3.6.2 3.6.3 3.7 3.8 3.9 3.10
Materials of Positive Dielectric Anisotropy . . . . . . . . . . . . . . . . . . 482 A Variable Tilt SmA Device . . . . . . . . . . . . . . . . . . . . . . . . . . 482 Dynamic Scattering in SmA Liquid Crystal Phases . . . . . . . . . . . . . . 483 Theoretical Predictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485 Response Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485 Displays Based on Dynamic Scattering . . . . . . . . . . . . . . . . . . . . 486 Two Frequency Addressed SmA Devices . . . . . . . . . . . . . . . . . . . 486 Polymer-Dispersed Smectic Devices . . . . . . . . . . . . . . . . . . . . . 487
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusions 489 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 489
XXVI Contents
Volume 2B
Part 11: Discotic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . 491
Chapter VI: Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . . . . . . . . 493 1 Synthesis of Chiral Smectic Liquid Crystals . . . . . . . . . . . . . . . . . 493
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 493 Long Pitch Chiral Smectic Liquid Crystals or Dopants . . . . . . . . . . . . 495
1.2.1 Schiff’s bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 496 1.2.2 Aromatic Esters with Alkyl Branched Alkyl Chains . . . . . . . . . . . . . 497
Aromatic Heterocycles with Alkyl-Branched Alkyl Chains . . . . . . . . . . 500 Esters and Ethers in the Terminal Chain . . . . . . . . . . . . . . . . . . . . 501 Halogens at the Chiral Center . . . . . . . . . . . . . . . . . . . . . . . . . 503
1.2.6 Cyclohexyl a-Fluorohexanoates . . . . . . . . . . . . . . . . . . . . . . . . 503 Gyano Groups at the Chiral Center . . . . . . . . . . . . . . . . . . . . . . 506 Optically Active Oxiranes and Thiiranes . . . . . . . . . . . . . . . . . . . 506 Optically Active y-Lactones . . . . . . . . . . . . . . . . . . . . . . . . . . 508 Optically Active S-Lactones . . . . . . . . . . . . . . . . . . . . . . . . . . 508 Miscellaneous Optically Active Heterocycles . . . . . . . . . . . . . . . . . 508 Short Pitch Chiral Smectic Liquid Crystals or Dopants . . . . . . . . . . . . 509 Optically Active Terphenyl Diesters . . . . . . . . . . . . . . . . . . . . . . 509 Optically Active Methyl-Substituted Dioxanes . . . . . . . . . . . . . . . . 510
1.4 Antiferroelectric Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . 510 1.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512
Stephen M . Kelly
1.2
1.2.3 1.2.4 1.2.5
1.2.7 1.2.8 1.2.9 1.2.10 1.2.1 1 1.3 1.3.1 1.3.2
2
2.1 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.3 2.3.1 2.3.2 2.3.3
Ferroelectric Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . 515 Sven T. Lagenvall Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515 Polar Materials and Effects . . . . . . . . . . . . . . . . . . . . . . . . . . 520 Polar and Nonpolar Dielectrics . . . . . . . . . . . . . . . . . . . . . . . . 520 The Nonpolarity of Liquid Crystals in General . . . . . . . . . . . . . . . . 522
Developments in the Understanding of Polar Effects . . . . . . . . . . . . . 527 The Simplest Description of a Ferroelectric . . . . . . . . . . . . . . . . . . 531 Improper Ferroelectrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536 The Piezoelectric Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539 The Necessary Conditions for Macroscopic Polarization in a Material . . . . 541 The Neumann and Curie Principles . . . . . . . . . . . . . . . . . . . . . . 541 Neumann’s Principle Applied to Liquid Crystals . . . . . . . . . . . . . . . 542 The Surface-Stabilized State . . . . . . . . . . . . . . . . . . . . . . . . . . 544
Behavior of Dielectrics in Electric Fields: Classification of Polar Materials . 523
Contents XXVII
2.3.4 2.3.5 2.3.6 2.3.7 2.4 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4.6 2.4.7 2.4.8 2.4.9 2.5 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7 2.5.8 2.5.9 2.5.10 2.5.11 2.6 2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.6.6 2.6.7 2.6.8 2.6.9 2.7 2.7.1 2.7.2 2.7.3 2.7.4 2.7.5 2.7.6 2.7.7 2.7.8
Chirality and its Consequences . . . . . . . . . . . . . . . . . . . . . . . . 548 The Curie Principle and Piezoelectricity . . . . . . . . . . . . . . . . . . . . 550 Hermann's Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 The Importance of Additional Symmetries . . . . . . . . . . . . . . . . . . 553 The Flexoelectric Polarization . . . . . . . . . . . . . . . . . . . . . . . . . 555 Deformations from the Ground State of a Nematic . . . . . . . . . . . . . . 555 The Flexoelectric Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . 556 The Molecular Picture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557 Analogies and Contrasts to the Piezoelectric Effect . . . . . . . . . . . . . . 558 The Importance of Rational Sign Conventions . . . . . . . . . . . . . . . . 559 The Flexoelectrooptic Effect . . . . . . . . . . . . . . . . . . . . . . . . . . 560 Why Can a Cholesteric Phase not be Biaxial? . . . . . . . . . . . . . . . . . 563 Flexoelectric Effects in Smectic A Phases . . . . . . . . . . . . . . . . . . . 564 Flexoelectric Effects in Smectic C Phases . . . . . . . . . . . . . . . . . . . 564 The SmA*-SmC* Transition and the Helical C* State . . . . . . . . . . . . 568 The Smectic C Order Parameter . . . . . . . . . . . . . . . . . . . . . . . . 568 The SmA*-SmC* Transition . . . . . . . . . . . . . . . . . . . . . . . . . 571 The Smectic C* Order Parameters . . . . . . . . . . . . . . . . . . . . . . . 573 The Helical Smectic C* State . . . . . . . . . . . . . . . . . . . . . . . . . 574 The Flexoelectric Contribution in the Helical State . . . . . . . . . . . . . . 576 Nonchiral Helielectrics and Antiferroelectrics . . . . . . . . . . . . . . . . . 577 Simple Landau Expansions . . . . . . . . . . . . . . . . . . . . . . . . . . 578 The Electroclinic Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583 The Deformed Helix Mode in Short Pitch Materials . . . . . . . . . . . . . 587 The Landau Expansion for the Helical C* State . . . . . . . . . . . . . . . . 588 The Pikin-Indenbom Order Parameter . . . . . . . . . . . . . . . . . . . . . 592 Electrooptics in the Surface-Stabilized State . . . . . . . . . . . . . . . . . 596 The Linear Electrooptic Effect . . . . . . . . . . . . . . . . . . . . . . . . . 596 The Quadratic Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599 Switching Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 600 The Scaling Law for the Cone Mode Viscosity . . . . . . . . . . . . . . . . 602 Simple Solutions of the Director Equation of Motion . . . . . . . . . . . . . 603 Electrooptic Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . 604 Optical Anisotropy and Biaxiality . . . . . . . . . . . . . . . . . . . . . . . 608 The Effects of Dielectric Biaxiality . . . . . . . . . . . . . . . . . . . . . . 610 The Viscosity of the Rotational Modes in the Smectic C Phase . . . . . . . . 613 Dielectric Spectroscopy: To Find the yand E Tensor Components . . . . . . 617 Viscosities of Rotational Modes . . . . . . . . . . . . . . . . . . . . . . . . 617 The Viscosity of the Collective Modes . . . . . . . . . . . . . . . . . . . . 618 The Viscosity of the Noncollective Modes . . . . . . . . . . . . . . . . . . 620 The Viscosity '/cp from Electrooptic Measurements . . . . . . . . . . . . . . 622 The Dielectric Permittivity Tensor . . . . . . . . . . . . . . . . . . . . . . . 622 The Case of Chiral Smectic C* Compounds . . . . . . . . . . . . . . . . . . 623 Three Sample Geometries . . . . . . . . . . . . . . . . . . . . . . . . . . . 625 Tilted Smectic Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626
XXVIII Contents
2.7.9 2.7.10 2.8 2.8.1 2.8.2 2.8.3 2.8.4 2.8.5 2.8.6 2.8.7 2.8.8 2.8.9 2.8.10 2.8.1 1 2.9 2.10
3
3.1 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.3 3.3.1 3.3.2 3.3.3 3.4 3.4.1 3.4.2
3.5
Nonchiral Smectics C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627 Limitations in the Measurement Methods . . . . . . . . . . . . . . . . . . . 628 FLC Device Structures and Local-Layer Geometry . . . . . . . . . . . . . . 629 The Application Potential of FLC . . . . . . . . . . . . . . . . . . . . . . . 629 Surface-Stabilized States . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630 FLC with Chevron Structures . . . . . . . . . . . . . . . . . . . . . . . . . 634 Analog Gray Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637 Thin Walls and Thick Walls . . . . . . . . . . . . . . . . . . . . . . . . . . 639 C1 and C2 Chevrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 644 The FLC Technology Developed by Canon . . . . . . . . . . . . . . . . . . 648 The Microdisplays of Displaytech . . . . . . . . . . . . . . . . . . . . . . . 650 Idemitsu’s Polymer FLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651 Material Problems in FLC Technology . . . . . . . . . . . . . . . . . . . . 653 Nonchevron Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655 Is There a Future for Smectic Materials? . . . . . . . . . . . . . . . . . . . 658 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 660
Antiferroelectric Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . 665
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665 Origin of Antiferroelectricity in Liquid Crystals . . . . . . . . . . . . . . . 665 Biased or Hindered Rotational Motion in SmC* Phases . . . . . . . . . . . 665 Biased or Hindered Rotational Motion in SmCA* Phases . . . . . . . . . . . 669 Spontaneous Polarization Parallel to the Tilt Plane . . . . . . . . . . . . . . 671 Obliquely Projecting Chiral AlkylChains inSmAPhases . . . . . . . . . . 673 Thresholdless Antiferroelectricity and V-Shaped Switching . . . . . . . . . 675 Tristable Switching and the Pretransitional Effect . . . . . . . . . . . . . . . 675 Pretransitional Effect in Antiferroelectric Liquid Crystal Displays . . . . . . 679 Langevin-type Alignment in SmCR* Phases . . . . . . . . . . . . . . . . . 682 Antiferroelectric Liquid Crystal Materials . . . . . . . . . . . . . . . . . . . 684 Ordinary Antiferroelectric Liquid Crystal Compounds . . . . . . . . . . . . 684 Antiferroelectric Liquid Crystal Compounds with Unusual Chemical Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 689
Kouichi Miyachi and Atsuo Fukuda
Chapter VII: Synthesis and Structural Features
1 General Structural Features . . . . . . . . . . . . . . . . . . . . . . . . . . 693
. . . . . . . . . . . . . . . . . . 693 Andrew N . Cammidge and Richard J . Bushby
2
2.1.1
Aromatic Hydrocarbon Cores . . . . . . . . . . . . . . . . . . . . . . . . . 694 2.1 Benzene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 694
Esters and Amides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 694