Dispersion and magnetic field-induced alignment of functionalized carbon nanotubes in liquid crystals

Liquid crystal (LC)-functionalized multi-walled carbon nanotubes (MWNTs) were synthesized by substituting decyloxy and phenylcyclohexyl (PCH) mesogenic moieties into MWNT surface through covalent linkage. The LC-functionalized MWNTs (LC-MWNTs) showed good dispersion stability in ethanol as well as good miscibility in a host thermotropic nematic LC (N-LC). A polarizing optical microscope image demonstrated that the LC-MWNTs could be well dispersed in the host N-LC within 5 wt% content of LC-MWNTs without aggregation, which is ascribed to the substantial affinity between the PCH moieties and the host N-LC molecules. It was found that the LC-MWNTs in the host LC matrix could be well aligned parallel to the direction of the applied magnetic field of 5 T. Then the high order parameter of 0.46 for LC-MWNTs was obtained from the measurement of polarized Raman spectroscopy.