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Interactions Between Carbon Nanotubes and Liquid Crystals in Binary Nematic Electro-Optic Cells

Published online by Cambridge University Press:  31 January 2011

Georgi Yordanov Georgiev
Affiliation:
[email protected]@assumption.edu, Assumption College, Natural Science, 500 Salisbury st, 104 Testa Center, Worcester, Massachusetts, 01609, United States, 6175087251
Erin A Gombos
Affiliation:
[email protected], Assumption College, Natural Science, Worcester, Massachusetts, United States
Michael B McIntyre
Affiliation:
[email protected], Assumption College, Natural Science, Worcester, Massachusetts, United States
Michael F Mattera
Affiliation:
[email protected], Assumption College, Natural Science, Worcester, Massachusetts, United States
Peter A. Gati
Affiliation:
[email protected], Assumption College, Natural Science, Worcester, Massachusetts, United States
Yaniel Cabrera
Affiliation:
[email protected], Tufts University, Physics and Astronomy, Medford, Massachusetts, United States
Peggy Cebe
Affiliation:
[email protected], United States
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Abstract

We studied the effects of multiwalled carbon nanotubes (MWCNTs) on the Freedericksz transition of a liquid crystal (LC) and calibrated the altitudinal angle of CNTs as a function of the electric field. In addition, we directed the azimuthal angle which gave us complete control of the 3D orientation of the CNTs. We constructed anti-parallel electro-optic cells using a nanocomposite at a concentration of 0.01% CNTs with 4-Cyano-4'-pentylbiphenyl (5CB) liquid crystal. This low concentration was necessary to achieve maximum transmission of electromagnetic radiation through the cell and to minimize the Van der Waals attraction between the CNTs responsible for their aggregation. We chose two dimensional microscopic transmission ellipsometry (2D-MTE) to measure the phaseshift of the polarized electromagnetic radiation through the cell and to derive from it the altitudinal angle of the CNTs. Our results show that in the presence of CNTs the Freedericksz transition occurs at 55% of the transitional electric field as compared to the control electro-optic cell without CNTs. The width of the Freedericksz transition narrows by a similar factor. The switching time of the cell decreased in the presence CNTs by 18.5%.

Type
Research Article
Copyright
Copyright © Materials Research Society 2010

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