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Diffusivity Maximum in a Reentrant Nematic Phase
Stranski-Lab for Physical and Theoretical Chemistry, Berlin Institute of Technology, 135 June 17th Street, Berlin 10623, Germany
Department of Chemical and Biomolecular Engineering, North Carolina State University, 911 Partners Way, Raleigh, NC 27695, USA
* Author to whom correspondence should be addressed.
Received: 28 April 2012; in revised form: 11 June 2012 / Accepted: 13 June 2012 / Published: 21 June 2012
Abstract: We report molecular dynamics simulations of confined liquid crystals using the Gay–Berne–Kihara model. Upon isobaric cooling, the standard sequence of isotropic–nematic–smectic A phase transitions is found. Upon further cooling a reentrant nematic phase occurs. We investigate the temperature dependence of the self-diffusion coefficient of the fluid in the nematic, smectic and reentrant nematic phases. We find a maximum in diffusivity upon isobaric cooling. Diffusion increases dramatically in the reentrant phase due to the high orientational molecular order. As the temperature is lowered, the diffusion coefficient follows an Arrhenius behavior. The activation energy of the reentrant phase is found in reasonable agreement with the reported experimental data. We discuss how repulsive interactions may be the underlying mechanism that could explain the occurrence of reentrant nematic behavior for polar and non-polar molecules.
Keywords: reentrant phase; nematic; dynamics; diffusion
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Stieger, T.; Mazza, M.G.; Schoen, M. Diffusivity Maximum in a Reentrant Nematic Phase. Int. J. Mol. Sci. 2012, 13, 7854-7871.
Stieger T, Mazza MG, Schoen M. Diffusivity Maximum in a Reentrant Nematic Phase. International Journal of Molecular Sciences. 2012; 13(6):7854-7871.
Stieger, Tillmann; Mazza, Marco G.; Schoen, Martin. 2012. "Diffusivity Maximum in a Reentrant Nematic Phase." Int. J. Mol. Sci. 13, no. 6: 7854-7871.