Two-step electrical percolation in nematic liquid crystals filled with multiwalled carbon nanotubes.
Percolation of carbon nanotubes (CNTs) in liquid crystals (LCs) opens the way for a unique class of anisotropic hybrid materials with a complex dielectric constant widely controlled by CNT concentration. Percolation in such systems is commonly described as a one-step process starting at a very low loading of CNTs. In the present study the two-step percolation was observed in the samples of thickness 250 μm obtained by pressing the suspension between two substrates. The first threshold concentration, C(n)(p(1))∼10(-4) wt.%, was sensitive to temperature and phase state of LC, while the second one, C(n)(p(2))∼10(-1) wt.%, remained practically unchanged in the temperature tests. The two-stage nature of percolation was explained on a base of mean-field theory assuming core-shell structure of CNTs.
Institute of Physics, NAS of Ukraine, Prospect Nauky 46, 03028, Kyiv, Ukraine.
Serhiy
S
Tomylko
Institute of Physics, NAS of Ukraine, Prospect Nauky 46, 03028, Kyiv, Ukraine.
Oleg
O
Yaroshchuk
Institute of Biocolloidal Chemistry named after F.D. Ovcharenko, NAS of Ukraine, Prospect Vernadskogo 42, 03142, Kyiv, Ukraine.
Nikolai
N
Lebovka
D004553:Electric Conductivity; D050866:Liquid Crystals / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry; D013696:Temperature
D037742:Nanotubes, Carbon