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Peter Palffy-Muhoray

Polymers

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Director Dynamics In Liquid-Crystal Physical Gels, Rafael Verduzco, Neal R. Scruggs, Samuel Sprunt, Peter Palffy-Muhoray, Julia A. Kornfield May 2007

Director Dynamics In Liquid-Crystal Physical Gels, Rafael Verduzco, Neal R. Scruggs, Samuel Sprunt, Peter Palffy-Muhoray, Julia A. Kornfield

Peter Palffy-Muhoray

Nematic liquid- crystal (LC) elastomers and gels have a rubbery polymer network coupled to the nematic director. While LC elastomers show a single, non- hydrodynamic relaxation mode, dynamic light- scattering studies of self- assembled liquid- crystal gels reveal orientational fluctuations that relax over a broad time scale. At short times, the relaxation dynamics exhibit hydrodynamic behavior. In contrast, the relaxation dynamics at long times are non-hydrodynamic, highly anisotropic, and increase in amplitude at small scattering angles. We argue that the slower dynamics arise from coupling between the director and the physically associated network, which prevents director orientational fluctuations from decaying …


Three-Dimensional Dye Distribution In Photo-Oriented Liquid-Crystal Alignment Layers, S. Bardon, D. Coleman, N. A. Clark, T. Kosa, H. Yuan, Peter Palffy-Muhoray Mar 2002

Three-Dimensional Dye Distribution In Photo-Oriented Liquid-Crystal Alignment Layers, S. Bardon, D. Coleman, N. A. Clark, T. Kosa, H. Yuan, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The three-dimensional optical anisotropy of photo-buffed dye-doped polymer films and the resulting orientation imparted to a liquid crystal in contact are probed using total internal reflection. Although the linearly polarized writing light generates a uniaxial distribution of dye molecules, the polymer films are biaxial, a result of symmetry breaking by the film surface.