Equilibrium and flow of cluster-forming complex fluids

Full text: In this talk, I will present an overview of the unusual properties of a novel class of systems in soft matter physics, in which cluster formation takes place in the complete absence of attractions. After formulating a mathematical criterion as a necessary and sufficient condition for cluster formation, I will discuss the unusual structural, dynamical and phononic properties of cluster solids in equilibrium, showing, among others, that these are diffusive, that they provide for a realization of the Einstein model of solids and that at low temperatures cluster solids posses infinitely many isostructural critical points. Under shear flow, cluster solids organize in forms resembling the Abrikosov lattice of superconductors and they show a pressure flow behavior typical of colloidal glasses. Finally, I will demonstrate the construction of realistic microscopic models that allow for the formation of cluster crystals in the computer, opening the way to their experimental realization. (author)