Ponente: Prof. Robert Leheny
Procedente: Universidad Johns Hopkins.


Complex fluids are soft materials that possess liquid-like
properties but that differ from simple liquids due to internal structure on
the nanometer or micrometer scale. Particles suspended in a complex fluid can
be subject to a variety of interactions including electromagnetic, elastic,
entropic, and interfacial forces. The study of these forces has provided
understanding of fundamental problems in soft-matter physics as well as new
avenues for applications. This talk will describe our work with ferromagnetic
particles, including wire-shaped and disk-shaped colloids, as probes of
complex-fluid behavior in several related systems. The magnetic properties of
these colloids enable us to apply robust and precisely controlled forces and
torques to them within the fluid environment. The first part of the talk will
discuss the behavior of particles in liquid crystals where we find the
particles are subject to unique, anistropic forces engendered by their
disruption of the liquid-crystal order. We will describe efforts to
characterize these forces and to control them as a means to manipulate and
organize the particles. The second part of the talk will discuss experiments
employing the particles as microrheological probes of soft materials with
strongly nonlinear mechanical response including shear-thinning wormlike
micelle solutions and protein layers at fluid interfaces.

Viernes 18 de agosto 2016
13 HR auditorio del IF