SMP Group Seminar: Critical Mechanics of Soft Matter

Professor Peter Schall, Van der Waals-Zeeman Institute, University of Amsterdam.

Professor Peter Schall will be presenting a seminar on his research.  All are welcome to attend.

Soft Matter is by definition highly susceptible to small forces, and shows intriguing mechanical properties upon deformation, which are central to e.g. biological functions and many applications. The time and length scales of soft materials make them ideally suited to obtain fundamental insight into the stability of matter such as the mechanical yielding of solids, and vice versa the emergence of rigidity in fluids known as gelation. Recent progress in non-equilibrium statistical mechanics offers exciting new frameworks for understanding these basic transitions. We use colloidal and biological model systems to obtain insight into the transition from flow to arrest. We find that yielding, the onset of material flow, manifests as a new continuous non-equilibrium phase transition, in which the flowing state percolates the otherwise rigid elastic material. On the other hand, we find that gelation can likewise be regarded as continuous non-equilibrium phase transition, where a solid-like structure percolates across an otherwise fluid system. Both transitions thus appear to be two sides of the same critical phenomenon. We also investigate congestion phenomena in traffic and transport. Using traffic simulations and experiments on biological motor proteins, we show that also these congestion phenomena show signs of a non-equilibrium critical point due to geometric exclusion of the driven particles. For further information please contact Dr Johan Mattsson (