Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions
The Planer-Smoluchowski Soft Matter (PSSM) Workshop on Liquid Crystals and Colloidal Dispersions was held on June 22, 2009 in historic city of Lviv in Ukraine.
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| Дата: | 2010 |
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Інститут фізики конденсованих систем НАН України
2010
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| Назва видання: | Condensed Matter Physics |
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| Цитувати: | Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions / I. Smalyukh, A. Trokhymchuk // Condensed Matter Physics. — 2010. — Т. 13, № 3. — С. 37101:1-6. — англ. |
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irk-123456789-321152012-04-09T12:26:57Z Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions Smalyukh, I. Trokhymchuk, A. Chronicle The Planer-Smoluchowski Soft Matter (PSSM) Workshop on Liquid Crystals and Colloidal Dispersions was held on June 22, 2009 in historic city of Lviv in Ukraine. 2010 Article Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions / I. Smalyukh, A. Trokhymchuk // Condensed Matter Physics. — 2010. — Т. 13, № 3. — С. 37101:1-6. — англ. 1607-324X http://dspace.nbuv.gov.ua/handle/123456789/32115 en Condensed Matter Physics Інститут фізики конденсованих систем НАН України |
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Chronicle Chronicle |
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Chronicle Chronicle Smalyukh, I. Trokhymchuk, A. Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions Condensed Matter Physics |
| description |
The Planer-Smoluchowski Soft Matter (PSSM) Workshop on Liquid Crystals and Colloidal Dispersions was held on June 22, 2009 in historic city of Lviv in Ukraine. |
| format |
Article |
| author |
Smalyukh, I. Trokhymchuk, A. |
| author_facet |
Smalyukh, I. Trokhymchuk, A. |
| author_sort |
Smalyukh, I. |
| title |
Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions |
| title_short |
Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions |
| title_full |
Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions |
| title_fullStr |
Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions |
| title_full_unstemmed |
Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions |
| title_sort |
planer-smoluchowski soft matter workshop on liquid crystals and colloidal dispersions |
| publisher |
Інститут фізики конденсованих систем НАН України |
| publishDate |
2010 |
| topic_facet |
Chronicle |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/32115 |
| citation_txt |
Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions / I. Smalyukh, A. Trokhymchuk // Condensed Matter Physics. — 2010. — Т. 13, № 3. — С. 37101:1-6. — англ. |
| series |
Condensed Matter Physics |
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2025-07-03T12:38:54Z |
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2025-07-03T12:38:54Z |
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1836629449654665216 |
| fulltext |
Condensed Matter Physics 2010, Vol. 13, No 3, 37101: 1–6
http://www.icmp.lviv.ua/journal
Chronicle
Planer-Smoluchowski Soft Matter Workshop
on Liquid Crystals and Colloidal Dispersions
Liquid crystals and colloidal dispersions are of vital importance for technological applications
and practical devices. Nowadays the high-quality displays, non-mechanical beam steering devices,
and switching elements in optical telecommunication networks can hardly be imagined without
liquid crystals. Liquid crystals composed of (or doped by) nano-sized particles are of interest for
a possible utilization in the emerging novel applications such as tunable and frequency selective
negative index media. The anticipated new technological developments are closely related to a
number of interesting problems in basic science of liquid crystal colloids that attract a great deal
of current interest.
The Planer-Smoluchowski Soft Matter (PSSM) Workshop on Liquid Crystals and Colloidal
Dispersions was held on June 22, 2009 in historic city of Lviv in Ukraine. The names of Planer
and Smoluchowski in the title of workshop as well as the city of Lviv as host are not accidental.
Two outstanding scientists – Julius Planer and Marian Smoluchowski – both have made pioneering
contributions to the modern understanding of liquid crystals and colloidal dispersions when they
used to live and work [during different periods of time] in city of Lviv. Julius Planer was born
in 1827 in Vienna and moved to Lviv in 1855 where till 1863 he headed Department of Anatomy
at Lviv University. Among others, in 1861 Planer published a paper in which he reported the
first experimental observations of the mesomorphic phase behavior and what is now known as
thermotropic liquid crystal. Marian Smoluchowski was born in 1872 near Vienna and in 1899
came to Lviv where he stayed till 1913 occupying different positions at Lviv University. Here in Lviv
Smoluchowski made many contributions to the physics of condensed matter. Particularly, in 1904 he
was the first who noted the existence of density fluctuations in the gas phase. In 1906, independently
of Albert Einstein, Smoluchowski found the theoretical explanation of Brownian motion, the piece
of work for which today he is best known. In 1908 Smoluchowski became the first physicist to ascribe
the phenomenon of critical opalescence to large density fluctuations. Thus, besides the scientific
goals PSSM Workshop on Liquid Crystals and Colloidal Dispersions celebrated the legacy of these
two outstanding scientists Julius Planer and Marian Smoluchowski, who both made pioneering
contributions to the understanding of these classical soft condensed matter systems.
The PSSM workshop was organized by the Institute for Condensed Matter Physics of the
National Academy of Sciences of Ukraine and the University of Colorado at Boulder and brought
together prominent scientists working at the forefronts of soft materials science and statistical
physics, postdoctoral fellows and students from around the world. The workshop was supported
by Ivan Franko National University of Lviv (modern name of the same Lviv University where
both fellow men used to work) and International Institute for Complex Adaptive Matter (ICAM-
I2CAM). ICAM-I2CAM is a distributed experiment-based multi-institutional partnership whose
purpose is to identify major new research themes in complex adaptive matter – the search for an
understanding of emergent behavior in hard, soft, and living matter. The PSSM workshop in Lviv
was the first workshop sponsored by ICAM-I2CAM in the Eastern Europe.
The one-day program of the workshop was quite intense, being composed of 6 invited lectures,
10 oral presentations as well as 16 poster presentations discussed during the lunch break. All
workshop events took place in the main building of the Ivan Franko National University of Lviv
and, particularly, in a beautiful Conference Hall formerly used by the Galician parliament. Invited
lectures were delivered by Slobodan Žumer from the University of Ljubljana, Matt Glaser from the
University of Colorado at Boulder, Matthias Ballauff from the University of Bayreuth in Germany,
c© I. Smalyukh, A. Trokhymchuk 37101-1
http://www.icmp.lviv.ua/journal
Pawel Bryk from Maria Curie-Sklodowska University in Lublin, Liang-Chy Chien from Kent State
University and Pawel Pieranski from the University of Paris-Sud.
Slobodan Žumer presented a lecture on the formation of complex assemblies of particles in
nematic phases. Description based on a Landau type approach coupled with topological theory
provides a useful tool for modeling these complex structures. Spacial emphasis was laid upon
recent modeling achievements that are contrasted with the latest experimental studies. In solvents,
where nematic order is present, an effective long-range interparticle coupling appears. It leads to
numerous organizations of colloidal particles not present in simple liquids. Of particular interest
are situations where topological constraint causes the sharing of a disclination by neighboring
particles which leads to a string-like coupling. Colloidal dimmers, chains, lattices, braids, and
hierarchal structures can be realized via disclination loops with singular or non-singular cores.
Authors expect that some of these structures will open new ways to the assembling of complex
structures needed for metamaterials.
Matt Glaser spoke on simulation studies of spherical nanoparticles in a nematogenic solvent
consisting of soft spherocylinders. Authors found that nanoparticles remain well dispersed in the
isotropic (low-density) phase of the solvent, but demix into a nanoparticle-poor nematic phase
and a nanoparticle-rich isotropic phase at higher pressures. When the nanoparticle-spherocylinder
interactions are modified to promote homeotropic anchoring, the solvent-induced interaction be-
tween nanoparticles in the isotropic phase exhibits strong intermediate-range repulsion that is
expected to further stabilize nanoparticle dispersions. However, many-body effects appear to domi-
nate nanoparticle-nanoparticle interactions in the isotropic phase with homeotropic anchoring even
at the lowest nanoparticle concentration investigated, resulting in suppression of the intermedi-
ate range repulsion and leading to nanoparticle aggregation. The effective interactions between
nanoparticles in nematogenic media are similar to depletion interactions in colloidal systems, sug-
gesting a strong analogy between nanoparticles in thermotropic liquid crystals and lyotropic mix-
tures of colloidal spheres and rods.
In his lecture Matthias Ballauff proposed a new way to determine weak repulsive forces oper-
ating between colloidal particles by measuring the rate of slow coagulation. According to Smolu-
chowski’s classical paper, the rate of slow coagulation is directly related to the competition of
the repulsion with thermal motion. Since the thermal forces are weak, measurements of the co-
agulation rate can provide precise information on repulsive potentials having a magnitude of just
a few kT . This novel way was illustrated by studying colloidal spherical polyelectrolyte brush
particles in aqueous solution containing trivalent La3+ counterions. The particles consist of a
monodisperse polystyrene core of 121 nm radius from which linear sodium poly(styrene sulfonate)
chains are densely grafted (contour length: 48 nm). Authors determined the rate of coagulation by
time-resolved simultaneous static and dynamic light scattering in presence of LaCl3. Direct mea-
surements of the repulsive forces between macroscopic brush layers demonstrate that the potential
decays exponentially with distance. This is in good agreement with a simple theoretical treatment
that furthermore leads to the effective surface potential and underscores the general validity of the
approach.
Pawel Bryk from Maria Curie-Sklodowska University in Lublin, Poland, spoke on theoreti-
cal investigations of effective interactions in colloidal suspensions. The bare interactions between
macroparticles are attractive at larger separations due to the dispersion forces between the atoms
forming the colloidal particles. In order to prevent aggregation, the colloidal suspension should be
stabilized either by charge or sterically. Technological developments during the last two decades
made it possible to prepare well-defined colloidal suspensions. With the help of video-microscopy
and total internal reflection microscopy effective interactions in colloidal suspensions can be mea-
sured directly, and compared with theoretical predictions. Author presented the results of inves-
tigations of the effective interactions in colloidal systems using modern liquid-state theories. He
also discussed the depletion interactions between a large colloidal particle, immersed in a “sea” of
smaller colloidal particles, and various substrates. The large colloidal particle was modeled as a
hard sphere, and the substrate has a certain geometrical (like a wedge, or an edge, or a regular pat-
tern created by decorating a structureless wall by hemispheres), or thermodynamical feature (like
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Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions
semipermeability to some of the components of a multicomponent mixture). These results were di-
scussed in the context of possible experimental realizations of such systems. The issue of the onset
of polydispersity on the effective interactions in colloidal suspensions with the attractive/repulsive
bare interactions was addressed as well.
Liang-Chy Chien spoke on tunable cholesteric liquid crystal color. It is known that cholesteric
liquid crystals (CLCs) in the planar texture possess a unique feature of separating incident light
into its left- and right-handed circular components by reflecting one component and transmitting
the other. In a planar aligned CLC with a preselected helical pitch only a single wavelength can
be Bragg reflected (monochrome). In addition to the temperature dependence of Bragg reflected
wavelength of a CLC, there are two ways to prepare multiple wavelength (or color) reflecting
CLCs; one method is by stacking multiple layers of CLCs with different cholesteric pitches to
reflect different wavelengths. In this case, the stacking is normally arranged in a fashion that CLC
reflecting a shorter wavelength is placed on top and the CLC reflecting a longest wavelength is
placed at the bottom of the stacked films. Alternatively, multiple (wavelengths) colors reflection
CLCs can be obtained in sequential arrangement in a single layer with CLCs, reflecting different
wavelengths or colors. A couple of approaches in tuning the cholesteric color were reported.
Pawel Pieranski presented a lecture on universal aspects of liquid crystals. Among others he
focused on a few selected topics that can be of interest also for non-specialists. In particular, he
spoke about Mark Kac (a famous mathematician from the Lviv School of Mathematics) and the
issue of isospectral drum initiated by him.
The short oral presentations focussed on recent advances bridging a gap between basic soft
condensed matter physics and applied science. In particular, Longin Lisetski from the Institute for
Scintillation Materials, STC “Institute for Single Crystals” of the National Academy of Sciences of
Ukraine delivered a collection of results obtained by using a model approach to molecular-statistical
description of liquid crystal phases with helical twisting and supramolecular heterostructuring.
Among the most convincing examples (which have not been paralleled by other known theoretical
descriptions of liquid crystal properties), one can note the following: (i) straightforward explana-
tion of substantially different helical twisting values and even different helical twisting sense of,
e. g. cholesteryl chloride and cholesteryl alkanoates (which have very close values of optical rota-
tion); (ii) numerous cases of extra helical twisting induced in cholesteric matrices by introduction
of non-chiral and non-mesogenic dopants, even in the absence of apparent specific interactions;
(iii) anomalous increase in the nematic phase thermal stability for certain mixtures containing
components of different chemical nature, etc. It was claimed that the proposed approach can be
very promising for a description of recently discovered and developed liquid crystalline systems
characterized as nanostructured or heterostructured ones (including liquid crystalline dispersions
of carbon nanotubes, nanorods and other shaped particles of organic and inorganic functional
materials, etc.).
Qingkun Liu from the Zhejiang University in China was talking about the assembly and ali-
gnment of plasmonic nanoparticles by lyotropic liquid crystals, which follows from the studies of
self-assembly and self-alignment of the gold nanorods dispersed in nematic and hexagonal lyotropic
liquid crystals. He also has discussed the novel plasmonic effects arising from the unidirectional
ordering of gold nanorods in these soft materials.
Yves Lansac from the Universite Francois Rabelais, Tours, France showed the results of coarse-
grained and atomistic simulations of calamitic and bent-core liquid crystals aimed at characterizing
nanophase segregation in smectics and exploring the molecular origins of tilt, spontaneous chirality,
polarization splay, and saddle-splay layer curvature in bent-core liquid crystals. It was found that
minimal models, incorporating the excluded volume interactions and differential intramolecular
flexibility, display most of the commonly observed smectic phases, including smectic C and tilted
hexatic phases of calamitic molecules, and spontaneously chiral and polarization splay modulated
(B1 and B7) phases of bent-core molecules. These findings suggest that thermotropic smectics can
be understood as flexibility or shape amphiphiles, in strong analogy to lyotropic liquid crystals.
Jaroslav Ilnytskyi from the Institute for Condensed Matter Physics, Lviv, Ukraine, discussed
what can be achieved by molecular dynamics simulation of liquid crystalline polymers. To illustrate
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this he presented three groups of results obtained quite recently. The first one concerns molecular
dynamics simulations of liquid crystalline dendrimers in isotropic, nematic and smectic A solvent.
Authors concentrate on orientational relaxation of the macromolecule and its equilibrium shape
depending on the phase of the solvent and the way the terminal mesogens are attached to the
dendritic core. The presented results are relevant in terms of the relation between the molecular
shape and bulk phase. The second problem addresses the origin of photo-induced deformations in
azobenzene-containing polymer films. Authors reproduced the opposite sign of the deformations
under uniform linearly polarized light in liquid crystalline and amorphous films, respectively. The
simulations shed some more light on underlying microscopic mechanisms of these deformations.
The third problem is the memory effects in liquid crystalline elastomers that are potentially at-
tractive for being applied as artificial muscles. Using molecular dynamics simulations the authors
reproduced the reversibility of the shape of lightly crosslinked melt of polymer liquid crystal when
driven via the smectic-isotropic transition. The presented examples demonstrate the possibilities
of molecular dynamics simulations in clarifying the microscopic mechanism behind various effects
and are a starting point for simulation driven predictions of the properties of new materials.
Shape controlled colloidal interactions in anisotropic fluids were reported by Clayton Lapointe
from University of Colorado at Boulder. Colloidal particles suspended in nematic liquid crystals
are known to exhibit highly directional interactions mediated by the elasticity of the liquid crystal.
Using lithographically fabricated platelet colloids, having equilateral polygonal shapes, the authors
showed that colloids with an even number of sides form elastic quadrupoles whereas those with
an odd number of sides form elastic dipoles. These qualitatively different interactions lead to
self-assembled structures that reflect the shape-dependent symmetries of elastic deformations in
the liquid crystal, demonstrating that colloidal interactions can be effectively controlled through
particle shape. The observed dipolar configuration requires no bulk topological defects, indicating
that dipole-dipole elastic interactions can be scaled down to submicron sizes, which is not possible
with spherical inclusions.
Colloidal nematostatics was presented and discussed by Victor Pergamenshchik from the In-
stitute of Physics of the National Academy of Sciences of Ukraine in Kyiv. Colloids interact via
the nematic director. As the interaction is of a long range, the nematic colloids are much closer to
electrostatic systems than to standard colloids in isotropic liquids. The author was talking about
an elastic “charge” and elastic multipoles, about their interaction and odd properties, e. g., elastic
charge is a vector, elastic dipole can be chiral, etc.
The report by Akihiko Matsuyama from Kyushu Institute of Technology in Japan was devoted
to the problem of phase separations in mixtures of a liquid crystal and a colloidal particles by
means of a mean-field theory. By taking into account a nematic and a smectic A ordering of liquid
crystals and a crystalline ordering of colloidal particles, the authors calculated the phase diagrams
on the temperature-concentration plane. They predict various phase separations, such as a smectic
A-crystal phase separation and a smectic A-nematic-crystal triple point, etc., depending on the
interactions between a liquid crystal and a colloidal surface. Inside binodal curves, authors found
new unstable and metastable regions which are important in the phase ordering dynamics. The
authors also found a crystalline ordering of colloidal particles dispersed in a smectic A phase and
in a nematic phase. The cooperative phenomena between liquid crystalline ordering and crystalline
ordering induce a variety of phase separations.
Stanislav Chernyshuk from the Institute of Physics of the National Academy of Sciences of
Ukraine in Kyiv, reported the results on a direct observation of the photochemical switching
between colloidal crystals with different lattice constants in a liquid-crystal emulsion. Glycerol
droplets being introduced in a nematic liquid crystal form two-dimensional hexagonal colloidal
crystal at the nematic-air interface with a lattice constant depending on the surface tension. The
authors dope an azobenzene derivative into the liquid crystal emulsion to modulate the colloidal
structures by using cis-trans photoisomerization of the doped dye. The photoisomerization changes
the surface tension and the lattice constant of colloidal crystals with a relaxation time T about
10 s. A simple theoretical description was proposed, which qualitatively agrees with experimental
results. Possible applications of photonic crystals in infrared range were discussed. The number N
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Planer-Smoluchowski Soft Matter Workshop on Liquid Crystals and Colloidal Dispersions
of different kinds of dyes set the number of different possible photonic crystals as 2N , which may
be transformed one into another by corresponding 2N light beams, inducing cis-trans photoiso-
merization of the doped dyes.
Jozef Spalek from Jagiellonian University in Krakow, Poland, presented a brief story on Marian
Smoluchowski in life and science. Finally, the report by ICAM-I2CAM Co-Director Daniel Cox from
the University of California at Davis was concerned the opportunities offered by ICAM-I2CAN to
nucleate and expand collaborations with US institutions.
It is important to note, that all presentations of the PSSM workshop were webcast in real time
and, in addition to the audience in the Conference Hall in Lviv, registered participants around
the world were able to participate, asking questions immediately after presentations. We conclude,
that being at the nexus of material science and soft condensed matter physics, the workshop theme
turned out to be inherently interdisciplinary and the PSSM Workshop enabled the researchers
working at the forefronts of basic and applied material science to discuss the recent advances in
the field of liquid crystals and colloidal dispersions.
Workshop Chairs,
Ivan Smalyukh
Department of Physics and the Liquid Crystal Materials
Research Center, and Renewable & Sustainable Energy Institute,
University of Colorado, Boulder, CO 80309, USA
Andrij Trokhymchuk
Institute for Condensed Matter Physics
of the National Academy of Sciences of Ukraine,
Lviv 79011, Ukraine
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