Impact of electric field on dissipative micro-patterns in cholesteric-nematic mixtures (COC-5CB) doped by multiwalled carbon nanotubes

Abstract

Microstructure and electrooptical properties of multiwalled carbon nanotubes (NTs), dispersed in the cholesteric liquid crystal (cholesteryl oleyl carbonate, COC), nematic 5CB and their mixtures, were studied at the fixed temperature of 298 K. The relative concentration X=COC(COC + 5CB) was varied within 0.0-1.0, the concentration C of NTs was varied within 0.01-1% wt. The value of X affected agglomeration and stability of NTs inside COC+5CB mixtures. High-quality dispersion, exfoliation, and stabilization of the NTs were observed in COC solvent (“good” solvent). From the other side, the aggregation of NTs was very pronounced in nematic 5CB solvent (“bad” solvent). The dispersing quality of solvent influenced the percolation concentration, corresponding to transition between the low conductive and high conductive states. Moreover, external electric field influenced the structure of dissipative micro-patterns and orientation of NTs in dependence of the value of X. The mixtures of COC and 5CB were found to be promising for application as functional media with controllable useful chiral and electrophysical properties.