Soft matter science covers colloids, liquid crystals, amphiphilic molecules, polymers and bio-related materials. One of the characteristic features of soft matter and their complexes lie in the spontaneous formation of various mesoscopic internal structures such as lamellar, hexagonal, cubic, emulsion, vesicles, and even random phases having different topologies and symmetries. A large number of internal degrees of freedom and characteristic nano- to micro-meter scale assemblies gives a soft nature to them. A unique feature of soft matter is that by applying small external fields, such as shear, electric field, magnetic field and chemical stimuli, the characteristic structures show noble non-equilibrium phenomena. Especially, rheological behavior coupled with the structure change induced by the external fields (structural rheology) and vesicle deformation induced by the chemical stimuli (biomembrane) are newly developing research topics in the non-equilibrium soft matter physics. The aim of the ISSP workshop is bringing together scientists on these two topics to encourage deep discussion, exchange of preliminary research information and presentation of young researchers.
In this session, we will discuss linear and non-linear rheology of soft matter systems. Due to the inherent mesoscopic length scales of structures, soft matter is generally very fragile and highly deformable even under weak external fields, leading to unique viscoelastic behaviors. In addition, the rheological properties of soft matter can be drastically changed when the internal structures are destroyed or disrupted due to the applied stress or flow. Since these problems are quite challenging and important from the viewpoint of physics, we shall call such a new subject as “structural rheology”. Although structural rheology constitutes an interesting class of soft matter physics, many important problems remain to be unsolved. Examples are such as viscoelasticity of periodic cubic structures, defect dynamics under external flow, structural relaxation and disruption of interfaces due to mechanical stresses, orientation transition under flow, and cross effect of external fields on rheology. The present workshop will focus on the latest experimental and theoretical (including simulations) results of structural rheology and explore its new directions and possible approaches in the future.
Cells and lipid vesicles can exhibit large morphological changes induced by flows, membrane phase separations, and chemical reactions. Examples are such as vesicle self-reproduction by chemical reaction, budding of multi-component vesicles, and flow-induced deformation of red blood cells. These membrane deformations are relevant to the biological response in living cells.