31 December 2009 Self-organized composites of multiwalled carbon nanotubes and nematic liquid crystal 5CB: optical singularities and percolation behavior in electrical conductivity
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Proceedings Volume 7388, Ninth International Conference on Correlation Optics; 738802 (2009) https://doi.org/10.1117/12.853075
Event: Correlation Optics 2009, 2009, Chernivsti, Ukraine
Abstract
This work discusses optical singularities and electrical conductivity behavior in a thin electrooptical cell filled with composites including multi-walled carbon nanotubes (MWCNTs) and nematic liquid crystal (LC). The MWCNTs with high aspect ratio L/d≈300 ÷ 1000 and nematic LC 5CB (4-pentyl-40-cyanobiphenyl) were used. The composites were prepared by introduction of MWCNTs (0.0001÷0.1% wt) into LC solvent with subsequent sonication. The increase of MWCNT concentration (between 0.005÷0.05 % wt) resulted in self-organization of MWCNTs and formation of micronsized aggregates with fractal boundaries. The visually observed formation of spanning MWCNT networks near the percolation threshold at ~0.025 % wt was accompanied with transition from non-conductive to conductive state and generation of optical singularities. The observed effects were explained by the strong interactions between MWCNTs and LC medium and planar orientation of 5CB molecules near the lateral surface of MWCNTs. It was speculated that optical singularities arose as a results of interaction of an incident laser beam with LC perturbed interfacial shells covering the MWCNT clusters. Behavior of the interfacial shell thickness in external electric field and in the vicinity of the nematic to isotropic transition was discussed.
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V. V Ponevchinsky, V. V Ponevchinsky, A. I. Goncharuk, A. I. Goncharuk, V. I. Vasil'ev, V. I. Vasil'ev, N. I. Lebovka, N. I. Lebovka, M. S. Soskin, M. S. Soskin, "Self-organized composites of multiwalled carbon nanotubes and nematic liquid crystal 5CB: optical singularities and percolation behavior in electrical conductivity", Proc. SPIE 7388, Ninth International Conference on Correlation Optics, 738802 (31 December 2009); doi: 10.1117/12.853075; https://doi.org/10.1117/12.853075
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