Pawel Pieranski, Maria Helena Godinho

Liquid Crystals

New Perspectives

• Gebundenes Buch

Produktbeschreibung

This book on liquid crystals reports on the new perspectives that have been brought about by the recent expansion of frontiers and overhaul of common beliefs. First, it explores the interaction of light with mesophases, when the light or matter is endowed with topological defects. It goes on to show how electrophoresis, electro-osmosis and the swimming of flagellated bacteria are affected by the anisotropic properties of liquid crystals. It also reports on the recent progress in the understanding of thermomechanical and thermohydrodynamical effects in cholesterics and deformed nematics and refutes the common belief that these effects could explain Lehmann's observations of the rotation of cholesteric droplets subjected to a temperature gradient. It then studies the physics of the dowser texture, which has remarkable properties. This is of particular interest in regards to nematic monopoles, which can easily be generated, set into motion and collided within it. Finally, this book deals with the spontaneous emergence of chirality in nematics made of achiral molecules, and provides a brief historical context of chirality

Produktdetails

• Verlag: Wiley
• Seitenzahl: 368
• Erscheinungstermin: 31. August 2021
• Englisch
• Abmessung: 240mm x 161mm x 24mm
• Gewicht: 721g
• ISBN-13: 9781789450408
• ISBN-10: 1789450403
• Artikelnr.: 62120001

Autorenporträt

Pawel Pieranski works at Laboratoire de Physique des Solides in Orsay, France. He has published a two-volume textbook on liquid crystals, written in collaboration with Patrick Oswald, and has conducted extensive research in many different areas of the field of liquid crystals. Maria Helena Godinho is Associate Professor at NOVA University Lisbon, Portugal. Between 2016 and 2020 she was Vice President of the International Liquid Crystal Society. In 2019 she was awarded the "Fréedericksz Medal" by the Russian Liquid Crystal Society.

Inhaltsangabe

Preface xi Chapter 1. Singular Optics of Liquid Crystal Defects 1 Etienne
BRASSELET 1.1. Prelude from carrots 1 1.2. Liquid crystals, optics and
defects: a long-standing trilogy 1 1.3. Polarization optics of liquid
crystals: basic ingredients 3 1.3.1. The few liquid crystal phases at play
in this chapter 3 1.3.2. Liquid crystals anisotropy and its main optical
consequence 3 1.3.3. Polarization state representation in the paraxial
regime 5 1.3.4. Polarization state evolution through uniform director
fields 6 1.3.5. Effective birefringence 8 1.3.6. Polarization state
evolution through twisted director fields 9 1.4. Liquid crystal
reorientation under external fields 15 1.5. Customary optics from liquid
crystal defects 16 1.5.1. Localized defects structures in frustrated
cholesteric films 17 1.5.2. Elongated defects structures in frustrated
cholesteric films 20 1.5.3. Regular optics from other topological
structures 24 1.5.4. Assembling photonic building blocks with liquid
crystal defects 31 1.6. From regular to singular optics 34 1.6.1. What is
singular optics? 34 1.6.2. A nod to liquid crystal defects 37 1.6.3.
Singular paraxial light beams 38 1.6.4. Generic singular beam shaping
strategies 41 1.7. Advent of self-engineered singular optical elements
enabled by liquid crystals defects 44 1.7.1. Optical vortices from a
cholesteric slab: dynamic phase option 44 1.7.2. Optical vortices from a
nematic droplet: geometric phase option 45 1.8. Singular optical functions
based on defects: a decade of advances 47 1.8.1. Custom-made singular
dynamic phase diffractive optics 47 1.8.2. Spontaneous singular geometric
phase optics 47 1.8.3. Directed self-engineered geometric phase optics 52
1.8.4. From single to arrays of optical vortices 58 1.9. Emerging optical
functionalities enabled by liquid crystal defects 58 1.9.1. Spectrally and
spatially adaptive optical vortex coronagraphy 59 1.9.2. Multispectral
management of optical orbital angular momentum 67 1.10. Conclusion 69 1.11.
References 70 Chapter 2. Control of Micro-Particles with Liquid Crystals 81
Chenhui PENG and Oleg D. LAVRENTOVICH 2.1. Introduction 81 2.2. Control of
micro-particles by liquid crystal-enabled electrokinetics 82 2.2.1.
Liquid-crystal enabled electrophoresis 85 2.2.2. Liquid crystal-enabled
electro-osmosis 91 2.3. Controlled dynamics of microswimmers in nematic
liquid crystals 96 2.4. Conclusion 104 2.5. Acknowledgments 107 2.6.
References 107 Chapter 3. Thermomechanical Effects in Liquid Crystals 117
Patrick OSWALD, Alain DEQUIDT and Guilhem POY 3.1. Introduction 117 3.2.
The Ericksen-Leslie equations 121 3.2.1. Conservation equations 121 3.2.2.
Molecular field 123 3.2.3. Constitutive equations 125 3.3. Molecular
dynamics simulations of the thermomechanical effect 130 3.3.1. Molecular
models 130 3.3.2. Constrained ensembles 131 3.3.3. Computation of the
transport coefficients 133 3.3.4. Analysis of the results 134 3.4.
Experimental evidence of the thermomechanical effect 135 3.4.1. The static
Éber and Jánossy experiment 136 3.4.2. Another static experiment proposed
in the literature 140 3.4.3. Continuous rotation of translationally
invariant configurations 142 3.4.4. Drift of cholesteric fingers under
homeotropic anchoring 165 3.5. The thermohydrodynamical effect 174 3.5.1. A
proposal for measuring the TH Leslie coefficient mu: theoretical prediction
175 3.5.2. About the measurement of the TH Akopyan and Zel'dovich
coefficients 178 3.6. Conclusions and perspectives 184 3.7. References 185
Chapter 4. Physics of the Dowser Texture 193 Pawel PIERANSKI and Maria
Helena GODINHO 4.1. Introduction 193 4.1.1. Disclinations and monopoles 193
4.1.2. Road to the dowser texture 197 4.1.3. The dowser texture 201 4.2.
Generation of the dowser texture 207 4.2.1. Setups called "Dowsons
Colliders" 207 4.2.2. "Classical" generation of the dowser texture 208
4.2.3. Accelerated generation of the dowser texture using the DDC2 setup
208 4.3. Flow-assisted homeotropic ==> dowser transition 210 4.3.1.
Experiment using the DDC2 setup 210 4.3.2. Flow-assisted bowser-dowser
transformation in capillaries 212 4.3.3. Flow-assisted homeotropic-dowser
transition in the CDC2 setup 213 4.3.4. Theory of the flow-assisted
homeotropic-dowser transition 214 4.3.5. Summary and discussion of
experimental results 216 4.4. Rheotropism 217 4.4.1. The first evidence of
the rheotropism 217 4.4.2. Synchronous winding of the dowser field 219
4.4.3. Asynchronous winding of the dowser field 225 4.4.4. Hybrid winding
of the dowser field with CDC2 228 4.4.5. Rheotropic behavior of pi- and
2pi-walls 228 4.4.6. Action of an alternating Poiseuille flow on wound up
dowser fields 231 4.5. Cuneitropism, solitary 2pi-walls 233 4.5.1.
Generation of pi-walls by a magnetic field 233 4.5.2. Generation and
relaxation of circular 2pi-walls 236 4.5.3. Cuneitropic origin of the
circular 2pi-wall 236 4.6. Electrotropism 239 4.6.1. Definition of the
electrotropism 239 4.6.2. Flexo-electric polarization 241 4.6.3. Setup 241
4.6.4. The first evidence of the flexo-electric polarization 242 4.6.5.
Measurements of the flexo-electric polarization 243 4.7. Electro-osmosis
246 4.7.1. One-gap system of electrodes 246 4.7.2. Two-gap system of
electrodes 250 4.7.3. Convection of the dowser field 252 4.8. Dowser
texture as a natural universe of nematic monopoles 253 4.8.1. Structures
and topological charges of nematic monopoles 253 4.8.2. Pair of dowsons d+
and d- seen as a pair of monopoles 255 4.8.3. Generation of
monopole-antimonopole pairs by breaking 2pi-walls 257 4.9. Motions of
dowsons in a wound up dowser field 262 4.9.1. Single dowson in a wound up
dowser field 262 4.9.2. The Lorentz-like force 263 4.9.3. Velocity of
dowsons in wound up dowser fields 266 4.9.4. The race of dowsons 266 4.9.5.
Trajectories of dowsons observed in natural light 270 4.9.6. Trajectories
of dowsons observed in polarized light 272 4.10. Collisions of dowsons 279
4.10.1. Pair of dowsons (d+,d-) inserted in a wound up dowser field 280
4.10.2. Cross-section for annihilation of dowsons' pairs 282 4.10.3.
Rheotropic control of the collisions outcome 283 4.11. Motions of dowsons
in homogeneous fields 285 4.12. Stabilization of dowsons systems by
inhomogeneous fields with defects 287 4.12.1. Gedanken experiment 287
4.12.2. Triplet of dowsons stabilized in MBBA by a quadrupolar electric
field 289 4.12.3. Septet of dowsons in MBBA stabilized by a quadrupolar
electric field` 290 4.12.4. Dowsons d+ stabilized by corner singularities
of the electric field 290 4.13. Dowser field submitted to boundary
conditions with more complex geometries and topologies 291 4.13.1. Ground
state of the dowser field in an annular droplet 291 4.13.2. Wound up
metastable states of the dowser field in the annular droplet 293 4.13.3.
Dowser field in a square network of channels, four-arm junctions 293
4.13.4. Triangular network, six-arm junctions 294 4.13.5. Three-arm
junctions 296 4.13.6. General discussion of n-arm junctions 296 4.14.
Flow-induced bowson-dowson transformation 298 4.15. Instability of the
dowson's d- position in the stagnation point 301 4.16. Appendix 1: equation
of motion of the dowser field 303 4.16.1. Elastic torque 303 4.16.2.
Viscous torques 304 4.16.3. Magnetic torque 306 4.16.4. Electric torque 306
4.17. References 306 Chapter 5. Spontaneous Emergence of Chirality 311
Mohan SRINIVASARAO 5.1. Introduction 311 5.2. Chirality: a historical tour
312 5.2.1. Chirality and optics 316 5.2.2. Chiral symmetry breaking and its
misuse 322 5.2.3. Spontaneous emergence of chirality or chiral structures
in liquid crystals 323 5.2.4. Spontaneous emergence of chirality due to
confinement 326 5.2.5. Spontaneous emergence of chirality due to
cylindrical confinement 329 5.2.6. Some misconceptions about optical
rotation 339 5.3. Concluding remarks 341 5.4. Acknowledgments 342 5.5.
References 342 List of Authors 347 Index 349