A02. Dynamics of Mesoscopic Structural Transitions

Soft matter forms a wide variety of mesoscopic structures using its large degrees of freedom. By applying external fields such as shear, electric fields, or guests, the mesoscopic structures show structural transitions, which brings a drastic change of the physical properties. The A02 team reveals the kinetic pathways from the viewpoint of the dynamical coupling between the order parameters and the external fields.

Research Projects

Imai group

Phase Transition Dynamics of Mesoscopic Structure in Soft Matter Induced by Guests

 

[ Leader ]	[ Member ]	[ Member ]
Masayuki Imai Ochanomizu University	Hajime Tanaka University of Tokyo	Ko Okumura Ochanomizu University

research subject

Soft matter forms mesoscopic molecular assembliesusing a large number of internal degrees of freedom.The soft assemblies may change their morphologies by applying external fields such as shear flow, electric field and so on.Furthermore by doping guest particles to the mesoscopic assembly, the potential energy that stabilize the mesostructure are modified by additional entropic potentials originated from the geometrical restriction of guests, which results in characteristic morphology transitions. Our group investigates such morphology transition induced by exotic circumstances from experimental, theoretical and simulation points of view and establishes the basic concept to describe the soft matter complex systems.

Orihara group

Topological Transition and Electro-Rheological Effect in Immiscible Polymer Blends

 

[ Leader ]	[ Member ]	[ Member ]
Hiroshi Orihara Hokkaido University	Seiji Ujiie Oita University	Yang-Ho Na Hokkaido University

research subject

It is well known that immiscible polymer blends have unique rheological properties compared with homogeneous liquids and their application is important. So far, we have found that some blends show topological changes in shear flow and electric fields, bringing about a drastic viscosity increase (electrorheological effect). When subjected to an electric field, for example, a droplet-dispersed structure changes into a network structure. This indicates that electric fields may be very effective to control the morphology and rheological properties of immiscible polymer blends. In our project, we construct a system that can make structural observations and rheological measurements simultaneously to elucidate the relationship between the structure and the rheology, and the phase transition mechanism in nonequilibrium states.

Kato group

Dynamics of Shear-Induced Structural Transition in Ordered Lyotropic Systems

 

[ Leader ]	[ Member ]	[ Member ]	[ Member ]
Tadashi Kato Tokyo Metropolitan University	Shigeyuki Komura Tokyo Metropolitan University	Masatoshi Fujii Shimane University	Youhei Kawabata Tokyo Metropolitan University

research subject

In recent years, much attention has been paid to the effects of shear flow on the structure of ordered lyotropic systems formed by amphiphiles such as surfactants, phospholipids, and block copolymers. Although various kinds of shear-induced transitions have been reported, their mechanisms have not yet been clarified. We are aiming to analyze time-evolution of structural transition by using small-angle neutron, X-ray, and light scattering and optical microscopy under shear flow, along side rheological measurements, mesoscopic-scale theoretical approaches, and computational simulations.

Kimura group

Dynamics of Mesoscopic Interface in Soft Matter and its Application

 

[ Leader ]	[ Member ]	[ Member ]	[ Collaborator ]
Yasuyuki Kimura Kyushu University	Takeshi Shimomura Tokyo University of Agriculture and Technology	Masatoshi Ichikawa Kyoto University	Yasutaka Iwashita Kyushu University

research subject

There are hierarchical mesoscopic structures within soft matter complex systems such as living ones. In these systems, various kinds of non-equilibrium phenomena including characteristic material transport in microscopic space enclosed by interfaces are important and essential for their functions. It is necessary to understand their structures and dynamics at mesoscopic scale for the control of their macroscopic structures and physical properties. In this study, we plan the following three projects. (1) We develop new experimental methods to observe the 3-dimensional local structure and local dynamics simultaneously. (2) We study the local mechanical properties in the hierarchical structure composed of bilayers by these methods. (3) We design new liquid crystal-polymer complexes under the control of their structures at mesoscopic scale.

Public Participation Research (2009-2010)

Noguchi group

Flow-induced Shape Transitions of Red Blood Cells and Fluid Vesicles

 

[ Leader ]
Hiroshi Noguchi University of Tokyo

research subject

Deformation of red blood cells allows passage of RBCs through a microvessel which diameter less than their diameters. In diseases such as diabetes mellitus, RBCs have reduced deformability and often block microvascular flow. The deformation of RBCs and fluid vesicles induce many dynamic modes but they are not well understood. We study the dynamics of deformed RBCs and vesicles in flows using theories and simulations.

Suzuki group

Amazing Morphologies Exhibited by Self-reproducing Vesicles Triggered by Chemical Reactions

 

[ Leader ]
Tadashi Sugawara University of Tokyo

research subject

We have studied cooperative dynamics of self-reproducing giant vesicles (GVs) triggered by chemical reactions, such as hydrolysis or dehydration to form a membrane molecule from a precursor, that occur at the surface of or inside GVs. Membrane dynamics of self-reproducing GVs consist of pudding, hole-opening, passing-through processes. We plan to elucidate these outstanding morphological changes of GVs at the microscopic level by correlating the membrane dynamics with local micro-domain formation of plural membrane molecules of GV using newly designed probe molecules and confocal microscopic images, etc.

Fujii group

Viscoelastic Dynamics of Shear-Induced Structural Transitio　and Destruction in the Lamellar Phase

 

[ Leader ]
Shuji Fujii Nagaoka University of Technology

research subject

Surfactant lamellar phases show various nonequilibrium phenomena under shear. One of the typical nonequilibrium phenomena is a shear-induced structural transition such as a lamellar-onion transition and a lamellar orientation transition. In this study, we aim to clarify not only the shear-induced nonequilibrium structural transition but also the destructive process by the use of the small angle scattering and viscoelastic measurements. We discuss the physical origin of the nonequilibrium structures formation under shear.

Hamada group

Pressure-induced Lateral Phase Separation within an Asymmetric Lipid Vesicle

 

[ Leader ]
Tsutomu Hamada Advanced Institute of Science & Technology

research subject

We investigate pressure-induced phase separation in multicomponent lipid vesicles. Lateral pressure within a bilayer membrane is controlled using a focused laser and micro-manipulation method. Then, we study lateral phase structures in asymmetric vesicles to understand the phase behavior in terms of the pressure balance between two leaflets.

Yamazaki group

Dynamics and Mechanism of Topological Changes of Biomembranes Induced by External Substances or External Fields

 

[ Leader ]	[ Member ]
Masahito Yamazaki Shizuoka University	Toshihiko Oka Shizuoka University

research subject

We investigate irreversible topological changes of lipid membranes/biomembranes induced by external substances or external fields to elucidate their kinetic pathways and mechanisms. Especially we focus our investigation on two physiologically important topological changes of biomembranes / lipid membranes as follows. (A) We investigate elementary processes of the pore formation in lipid membranes induced by interactions of antimicrobial peptides with the membranes using the singe GUV method, and elucidate the mechanism of their pore formation. (B) We investigate the effects of membrane proteins and temperature on electrostatic interactions-induced phase transitions between the bicontinuous cubic (Q) phases and the Lα phase and also the structural transformations from large unilamellar vesicles (LUVs) to Q phases.

Kawaguchi group

Shear Induced Changes in Aggregated Structures and Rheological Properties of Silica Suspensions

 

[ Leader ]
Masami Kawaguchi Mie University

research subject

In this project, three major points have to be resolved before we conclude the sustained oscillations of silica suspensions accompanied with transition of the aggregated structures induced by shear flow as rheochaos: 1) Firstly, the interactions between the suspended silica particles and dispersants as well as the shear rate effects on the preparations of the silica suspensions should be investigated; 2) Secondly, the structural investigations by scattering techniques like SALS or SANS or SAXS would help to interpret the shear flow properties; 3) Thirdly, some comparisons of the experimental results and analytical methods proposed for rheochaos should be performed to confirm our proposed model.

Jinnai group

Direct Three-Dimensional Observations of the Growth Points in Order-Order Transition in Block Copolymers

 

[ Leader ]
Hiroshi Jinnai Kyoto Institute of Technology	WPI Advanced Institute for Materials Research

research subject

The order-order transition (OOT) from one type of microdomain to the other, e.g., from the bicontinuous double-gyroid (G) structure to the hexagonally-packed cylindrical (C) structure in a poly(styrene-block-isoprene) (SI) block copolymer, will be investigated using transmission electron microtomography. The boundary structures of the G and C microdomains during the OOT will be visualized in three--dimension, from which the mechanism of the OOT will be discussed.

Fukuda group

Continuum Simulation Study of Three-dimensional Ordered Structures　of Liquid Crystals

 

[ Leader ]
Jun-ichi Fukuda National Institute of Advanced Industrial Science and Technology

research subject

By using continuum simulations, we will investigate equilibrium and non-equilibrium properties of three-dimensional ordered structures of liquid crystals. Our research targets include structures with orientational order such as cholesteric blue phases, and ones with both positional and orientational order such as twist-grain-boundary (TGB) phases and smectic blue phases. We will mainly focus on thermodynamic properties, processes of ordering, dynamics of phase change, and the effect of thermal fluctuations on those ordered structures.