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Interactions between spherical colloids mediated by a liquid crystal: A molecular simulation and mesoscale study

J. Chem. Phys. 121, 1949 (2004); doi:10.1063/1.1761054

Issue Date: 22 July 2004

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Evelina B. Kim, Orlando Guzmán, Sylvain Grollau, Nicholas L. Abbott, and Juan J. de Pablo
Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin 53706
Monte Carlo simulations and dynamic field theory (DyFT) are used to study the interactions between dilute spherical particles, dispersed in nematic and isotropic phases of a liquid crystal. A recently developed simulation method (expanded ensemble density of states) was used to determine the potential of mean force (PMF) between the two spheres as a function of their separation and size. The PMF was also calculated by a dynamic field theory that describes the evolution of the local tensor order parameter. Both methods reveal an overall attraction between the colloids in the nematic phase; in the isotropic phase, the overall attraction between the colloids is much weaker, whereas the repulsion at short range is stronger. In addition, both methods predict a new topology of the disclination lines, which arises when the particles approach each other. The theory is found to describe the results of simulations remarkably well, down to length scales comparable to the size of the molecules. At separations corresponding to the width of individual molecular layers on the particles' surface, the two methods yield different defect structures. We attribute this difference to the neglect of density inhomogeneities in the DyFT. We also investigate the effects of the size of spherical colloids on their interactions. ©2004 American Institute of Physics.
History: Received 18 March 2004; accepted 21 April 2004
Permalink: http://link.aip.org/link/?JCPSA6/121/1949/1
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KEYWORDS and PACS

Keywords
PACS
  • 61.30.Cz
    Molecular and microscopic models and theories of liquid crystal structure
  • 61.30.Jf
    Defects in liquid crystals
  • 82.70.Dd
    Colloids
  • YEAR: 2004

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PUBLICATION DATA

ISSN:
0021-9606 (print)   1089-7690 (online)
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REFERENCES (35)
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