EPJ

2024 Impact factor 2.2
EPJ E - Soft Matter and Biological Physics
Soft Matter and Biological Physics


Eur. Phys. J. E 7, 267-272 (2002)
DOI: 10.1140/epje/i200101176

Rotational viscosity enhancement in nematic liquid crystal near a charged surface

A.V. Zakharov and R.Y. Dong

Department of Physics and Astronomy, Brandon University, Brandon, Manitoba R7A 6A9, Canada

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(Received 22 November 2001 and Received in final form 31 January 2002)

Abstract
The effective rotational viscosity coefficient $\gamma^{\rm eff}_1$ and flow alignment angle $\theta_{\rm eff}$ are investigated for polar liquid crystals (LCs), such as 4- n-octyloxy- $4^{\prime}$-cyanobiphenyl (8OCB), in the vicinity of a charged bounding surface. $\theta_{\rm eff}$ is calculated using the Ericksen-Leslie theory, both for stationary and nonstationary regimes. Calculations of $\gamma^{\rm eff}_1$, both for homeotropic and planar alignment of 8OCB molecules, at a charged indium tin oxide(ITO)-coated glass plate show an additional contribution to $\gamma^{\rm eff}_1$ up to $7.8 \%$. The nonequilibrium flow alignment angle $\theta_{\rm eff} (\tau)$ is also calculated for the surface region bounded by $0.1 \le y \le 3.0$  $\mu $m. Transition from a tumbling situation to a flow aligning regime can occur near the charged boundary surface.

PACS
61.30.Cz - Molecular and microscopic models and theories of liquid crystal structure.
66.20.+d - Viscosity of liquids; diffusive momentum transport.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002

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