Systems Matter Seminar | Active Stress as a Path to Engineering Dynamic Materials

Abstract: Developing materials with lifelike functionalities requires fundamental interdisciplinary insights from physics, chemistry, and material science. Inspiration often comes from biology where nanoscopic machineries continuously consume energy to assemble, disassemble, compartmentalize, and transport matter. Dr. Kolvin will describe two experimental systems in which molecular motors drive liquids and solids into far-from-equilibrium dynamical states. In the first system, microtubule filaments and kinesin motors are merged with liquid-liquid phase separating polymers. Dr. Kolvin will show that active liquid-liquid phase separation is remarkably different from its equilibrium version. Active stresses split droplets, excite traveling waves along the liquid-liquid interfaces, and push wall-climbing wetting layers. In a second set of experiments, Dr. Kolvin's group let microtubules and kinesin motors sterically interact with self-bundling actin filaments. Initially uniformly dispersed, the actin bundles were assembled into a thin elastic membrane by active flows. Membranes, actuated by active stresses, developed fluctuating wrinkles and folds, and centimeter-scale shear oscillations. These examples show that active stress is a practical paradigm for controlling the assembly and dynamics of materials.

Bio: Itamar Kolvin received his B.Sc. (2007) in Physics and Mathematics and his M.Sc. (2009) from the Hebrew University in Jerusalem. In 2017, he completed his Ph.D. in Physics under Prof. Jay Fineberg in the Hebrew University. He was a HFSP cross-disciplinary postdoctoral fellow in the Physics Department, University of California, Santa Barbara with Pro. Zvonimir Dogic. His research interests are in the fundamentals of soft matter out-of-equilibrium: assembly, deformation, flow and fracture. Current efforts make use of model systems that are assembled of protein machineries to investigate active and adaptive material mechanics.