In this week's installment of the Physics Colloquium series, Zvonimir Dogic (UCSB) will present “Shape and topological transitions of elastic membranes” at 4:00 PM in Swain W. 119.
Abstract: Changes in the geometry and topology of thin elastic sheets underlie diverse processes across cellular biology, material science, and engineering. W investigate the fundamental properties of such transitions using a model experimental system of colloidal membranes, which assemble when mixing monodisperse micron-long viruses and non-adsorbing polymer. The physics of these micron-thick fluid-like assemblages are analogous to those of two-dimensional lipid bilayers.
However, their micron size allows for visualization of various membrane-based processes that are not possible using nanometer-sized conventional membranes. In one example, we use colloidal membranes to study how a flat 2D disk-like membrane folds into an edgeless vesicle-like structure. In another example, we study how a colloidal membrane composed of rod-like molecules of differing lengths folds into 3D structures. Above a critical concentration of shorter rods flat, 2D membranes become unstable and assume a bewildering variety of different shapes and topologies. Simple arguments suggest that doping colloidal membranes with miscible shorter rods tunes the membrane’s Gaussian modulus, which in turn destabilizes flat 2D membranes.
The College of Arts