Title: Geometry and mechanics of self-assembled colloidal membranes
Abstract: Colloidal membranes are an example of a novel bioinspired soft material with rich properties that stem from the interplay of geometry and molecular order. The colloidal membranes we study in collaboration with the Dogic Lab (UCSB/Brandeis) are two-dimensional monolayers composed of rod-like viruses roughly 1 micron long that are bound by entropic depletion forces. Because of their relatively large (micron) size, these membranes can be manipulated directly in the laboratory, offering a promising avenue to understand other similar systems of biological importance such as lipid bilayer membranes or the endoplasmic reticulum. However, colloidal membranes are not without their own distinct features. Most notably, the rods in the bulk are normal to the membrane surface, while the rods close to the edge twist to reduce the interface. The constituent rods can also be chiral, so that they prefer to align with a twist, reminiscent of a cholesteric liquid crystal. This microstructure endows colloidal membranes with a propensity to form exotic shapes such as helicoidal ribbons and unduloids. In this talk, we will explore these shapes and characterize the conditions under which they appear.