Kathleen Stebe - University of Pennsylvania

Thursday, April 19th, 2018 - 3:30 pm in ETLC 1-001

Abstract:

"Geometric Strategies for Directed Assembly of Colloids in Soft Matter"

Assembly of small components to make organized super-structures or reconfigurable entities
pervade science and engineering. In self-assembly, weak, order k B T interactions between
molecules or colloids are exploited, typically to form close-packed superstructures. In directed
assembly, external fields are applied to drive structure formation. We take a different approach
to directed assembly. We define and exploit energy landscapes in confined soft matter hosts by
controlling their shape and boundary conditions. Colloids placed in these hosts create
deformations that cost energy. Since these deformations decay over distances similar to the
particles, there is an energy field around the particle. This field depends on the energy landscape
in the host, which is shaped by confinement. Particles migrate and assemble guided by this
dependence with remarkable fidelity. This phenomenon is remarkably rich and reveals new
physics of interaction. We discuss three examples: capillary interactions between microparticles
on curved fluid interfaces, colloids on curved lipid bilayer vesicles and particles in confined
nematic liquid crystals.

Biography:

Kate's primary research interests are in non-equilibrium interfaces, with applications ranging from microfluidics to nanotechnology. One aspect of her research program focuses on interfaces between fluids and how surfactants can be used to influence interfacial flows. Other aspects address tailoring of solid-liquid interfaces with applications ranging from patterned electrodeposition to capillary-driven assembly and ordering of nanomaterials.

Hosts:

Dr. Hongbo Zeng & Dr. John Shaw