Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster: Wetting, Micro and nanofluidics

CPP 21.7: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

Microfluidic investigation of the electric-field-induced Frederiks transition in nematic liquid crystals in conjunction with a flow field — •Pramoda Kumar, Anupam Sengupta, and Christian Bahr — Max-Planck-Institute for Dynamics and Self-Organization, Göttingen, Germany

Microfluidic studies of nematic liquid crystals (LCs) offer interesting insights into hydrodynamics of anisotropic fluids, dynamics of topological defects and effects of confinement and surface anchoring of LC molecules on experimental outcomes [1,2,3]. In the present study, we use microfluidics to investigate the effect of flow on the electric-field-induced Frederiks transition in nematic liquid crystals. Depending on the direction of the applied electric field with respect to the equilibrium orientation of the LC molecules in flow, the orientational effects of the electric field can be either enhanced or reduced by varying the flow velocity. Effectively, we demonstrate the competing effects between flow and electric field induced orientation of the LC molecules. By tuning the flow velocity, the threshold voltage of the Frederiks transition can be adjusted. This phenomenon can be potentially utilized in display industry where there is an ever growing need for low energy consumption coupled with low response times.

[1] C. J. Holmes, S. L. Cornford and J. R. Sambles, Phys. Rev. Lett. 104, 248301 (2010).

[2] A. Sengupta, S. Herminghaus and Ch. Bahr, Mol. Cryst. Liq. Cryst. 547, 203 (2011).

[3] A. Sengupta, U. Tkalec and Ch. Bahr, Soft Matter 7 6542 (2011).