Condensed Matter Experiment
Zvonimir Dogic’s research covers several areas in complex fluids and biological physics. The objective of his research is to understand and control the self-assembly of matter on a colloidal length scale. The basic building blocks used are colloids of chemical or biological origin with well controlled spherical or rod-like shape and polymers with varying persistence length. The interactions between these components are well understood and can be modified in systematic ways. Despite the simplicity of these building blocks, they assemble into a variety of novel structures with unexpected complexity, e.g. 2D smectic phases, colloidal membranes, twisted chiral ribbons, and lamellar and columnar phases. These processes of self-assembly are under thermodynamic control and we use statistical mechanics to understand the final equilibrium structures. In the future we intend to study the assembly, phase transitions and dynamics of colloidal systems under non-equilibrium conditions. Current topics include rods in shear flow, polymers in nematics, isotropic-smectic phase transition, chiral ribbons, 2D smectic phases, lamellar melting, and studies of the fd virus.
Seth Fraden and his group seek to understand the relation between interparticle interactions and phase transitions in colloidal suspensions such as genetically engineered viruses, latex, proteins, and polymers. Combining experiment, computer simulation, and theory, Fraden examines the role of entropy in driving disorder-to-order transitions. One application is in nanotechnology where entropy driven assembly principles are being developed to construct novel layered materials. Other major objectives are to understand the physics of protein crystallization and the development of “lab on a chip” technology, which incorporates microfluidics to build high throughput devices for biotechnology.
Robert Meyer studies complex fluid systems, including liquid crystals, colloidal suspension, and polymers, all systems with a degree of internal structure and order, but not the perfectly regular order of crystals. They attempt to understand these systems in terms of both their fundamental microscopic ordering and their macroscopic phenomenology, which is very rich in nonlinear phenomena of all kinds. This latter subject has led to new research projects in chaotic dynamics in both dissipative hydrodynamic systems and electronic circuits. Experimental techniques include x-ray and light scattering, optical microscopy with computerized image analysis, and simulations. Theory is developed where appropriate. There are close collaborations with other members of the complex fluids group.