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Molecular Dynamics Simulation Of A Cyclic Siloxane Based Liquid Crystalline Material

Published online by Cambridge University Press:  16 February 2011

Soumya S. Patnaik ,
Ruth Pachter ,
Steve Plimpton  and
W. WADE ADAMS
Soumya S. Patnaik
Affiliation:
University of Virginia. Mailing address: WL/MLPJ, Wright-Patterson AFB, OH 45433
Ruth Pachter
Affiliation:
WL/MLPJ, Wright-Patterson AFB, OH 45433
Steve Plimpton
Affiliation:
Dept. 1421, Sandia National Laboratories, Albuquerque, NM 87185
W. WADE ADAMS
Affiliation:
WL/MLPJ, Wright-Patterson AFB, OH 45433
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Abstract

We have used molecular dynamics (MD) to study the room temperature bulk phase behavior of a cyclic siloxane with a pentamethylcyclosiloxane core and biphenyl-4-allyloxybenzoate Mesogens (BCS). This Material exhibits thermotropic liquid crystalline behavior above 120 °C. Bonded and non-bonded interactions were considered and a Molecular Mechanics force field was used to model the structural anisotropy of the siloxane Molecules. Molecular clusters with and without periodic boundary conditions (pbc) were studied to investigate the effect of the finite system size on the time evolution of the molecular structure. The precise nature of the boundary conditions was found to be significant and simulations that exclude pbc were better able to model the molecular system. It was found that molecular shapes associated with low energy conformations were not cylindrically symmetric but more splayed like. An approximate measure of the shape of the mesogens was obtained by describing ellipsoids around the Mesogens, and estimating the molecular length, breadth, and width from the principal axes of the ellipsoids. The orientational order was then calculated by defining the molecular axis to be along the major principal axis.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 328: Symposium Q – Electrical, Optical, and Magnetic Properties of Organic Solid State Materials , 1993 , 711
Copyright
Copyright © Materials Research Society 1994

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References

REFERENCES

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