March 01, 2006 (Wednesday)

Taming Competing Length Scales in Electrostatics and Self- Assembly

Christian Santangelo
Department of Physics and Astronomy
University of Pennsylvania

Complex fluids differ from simple fluids by the wealth of phenomena they are able to exhibit. This complex behavior can emerge from the interplay between physics on different length scales. As one example of this, the short-distance correlations between ions has been implicated in several nonintuitive phenomena, including the bundling of like-charged molecules. I will discuss my recent work constructing a coarse-grained model for charged systems that also accounts for these short-distance ionic correlations. A number of physically appealing conclusions emerge naturally from this framework, allowing a description of the behavior of ions both near and far from highly charged surfaces. I will also describe a system of particles with isotropic, repulsive interactions on two length scales that exhibits an extremely rich phase diagram. In two dimensions, this includes cluster, striped, and inverse micellar phases reminiscent of other self-assembling systems with more complicated (and attractive) interactions. I will extend my method to study the morphology of this repulsive self- assembly.
 

Time: 3:00 pm
Location: Lecture Room 5

The reception will be at 2:30 pm in room N201