285816 Nanoparticles in Liquid Crystals, and Liquid Crystals in Nanoparticles

Wednesday, October 31, 2012: 1:10 PM
415 (Convention Center )
Juan J. DePablo, Institute for Molecular Engineering, University of Chicago, Chicago, IL

Liquid crystals are fascinating materials whose structure and properties can be controlled through a variety of means, including temperature, magnetic fields, flow fields or concentration. The properties of liquid crystals are particularly sensitive to interfaces; molecular events that occur at a liquid crystal interface can in fact be amplified over macroscopic length scales, thereby providing the basis for a wide range of applications. In this presentation we elaborate on this feature of liquid crystals in the context of two applications. In the first, we show how the aggregation of nanoparticles in liquid crystals can be finely tuned by controlling the interaction (or anchoring) of the liquid crystal at the particles' surfaces. It is also shown that by controlling aggregation, one can induce the formation of gels. In the second application, liquid crystals are confined to small droplets. By controlling the orientation of the liquid crystals at the droplets' interfaces, it is possible to drive morphological transitions that can in principle be used for detection of analytes. Perhaps more intriguing is the finding that the structure of the liquid crystal itself can be projected onto such interfaces, leading to formation of nanoscale surface phases reminiscent of those encountered in self-assembling materials in three dimensions.

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