Bridging the Scales in Dipolar Soft Matter

In the present project we would focus on the dipolar systems. These dipoles can have absolutely different nature: from polar molecules, and accidentally formed charge pairs in ionic liquids to dipoles created by ferromagnetic ordering of spins in the crystalline lattice and many others. The systems we would deal with in this Project are the following: Electric Dipoles (Ultra-Cold Polar Molecules, Ionic Liquids); Magnetic Dipoles (Magnetic Fluids, Magnetic Gels, Micron-sized Anisotropic Magnetic Particles, namely, Capped Colloids, Magnetic Janus Particles, Magnetic Rods, Ellipsoids and Cubes). The Project is based on a fine weave of statistical physics and different computer simulation techniques. The verification of the results and adjustments of the theoretical models will be done in the close collaboration with various experimental groups. The main idea of the project is that independently on the size of the dipolar "building blocks", all these systems are fundamentally similar, and, in general terms, theoretical approaches and simulation tools once developed when studying one of those systems, can turn out to be applicable to describe dipolar systems with absolutely different characteristic lengths. Thus, the principal aim of the project is to broaden the understanding of dipolar soft matter at different scales by extending and generalising the existing theoretical and simulation methods and developing novel approaches. Being theoretical, the Project will be executed in the cooperation with experimentalists to both verify newly developed theories and assist in designing new smart soft dipolar materials on various scales. During the first three years we will mainly focus on the detailed analysis of microstructure of the aforementioned systems, and the last three years will be dedicated to the description of the mechanical, rheological and other macroproperties of the materials. This split allows us to unite the methods and approaches, thus following the main idea of the Project, namely bridging the scales in dipolar soft matter. Of course, we will also find new ideas and/or materials during this period, which can attract our interests and nicely complement the content. We will be also able to investigate the relationship between the microstructure and the macroscopic behaviour of dipolar systems. Formally, this project will lead to accomplishing 2 PhD thesis, 3-4 post-doctoral projects, 4-5 diploma thesis, one habilitation (of the applicant), and more than 20 peer-reviewed papers. The Project will also enhance the existing collaboration and establish new one between the host and various institutions in Austria, Europe and Russia. For the applicant this Project will mean the possibility of research career development in Austria, opening new perspectives for the future Professorship. This Project is aimed at summarising the experience and developing new approaches for describing dipolar systems in different branches of physics, chemistry, bio-physics, and we believe it will open new perspectives both for fundamental research and development of new materials.

Nowadays, materials whose properties can be fine-tuned by external fields of moderate and low strengths are widely studied. Of special interest are "green" or environmentally friendly systems and biologically compatible materials to be used in medical applications. For this magnetic soft matter -- liquids and gels with magnetic nano- or micron-sized particles inside -- is highly suitable. In order to obtain a system with desired and easily controllable response to magnetic fields, one needs to design this system on the level of its microstructure. Experimental studies of these new dipolar "smart materials" often involve rather expensive equipment and compounds, and can turn to be really time consuming. Thus, the first step would be to predict theoretically what is the link between a certain microstructure and the macroscopical behaviour of the system. The main idea of the START project was that independently on the size of the dipolar "building blocks", all these systems -- magnetic fluids, magnetic gels and elastomers, magnetic an isometric colloids -- are fundamentally similar, and, in general terms, theoretical approaches and simulation tools once developed when studying one of those systems, could be applicable to describe dipolar systems with absolutely different characteristic lengths. The project was based on a fine weave of statistical physics and different computer simulation techniques. The verification of the results and adjustments of the theoretical models was done in the close collaboration with various experimental groups. In the framework of this project we discovered the mechanisms of magnetic nanoparticle hierarchical self-assembly in magnetic fluids, investigated the influence of temperature and particle concentration on these processes. Based on this finding the first steps were done to understand the dynamics of magnetic fluids. We established the dependence of magnetic gel mechanical and magnetic properties and gel internal structure. We studied the properties of magnetic nano- and micron-sized cubes, magnetic ellipsoids and platelets, magnetic Janus particles and magnetic filaments. We showed that the shape of the particles plays a decisive part in their assembly and response. We put forward the approach to investigate active magnetic particles and direct their propulsion with external magnetic fields. This project helped to bring up highly qualified young researches and brought magnetic soft matter closer to broad audience through school workshops, public lectures and exhibitions. At the same time, this project opened up the whole new direction in soft matter physics.