Carbon nanotubes can be aligned by dispersing them in a liquid crystalline matrix. To control and optimize the obtained alignment it is important to understand the interactions between the molecules of the liquid crystal host phase and the carbon nanotubes. To this end we have carried out resonant Raman spectroscopy investigations of dispersions of single-wall carbon nanotubes (SWCNTs) in a liquid crystal compound comprising molecules with a biphenyl rigid core structure. We detect a distinct wavenumber shift of the radial breathing modes, confirming that the carbon nanotubes interact with the surrounding liquid crystal molecules, most likely through aromatic interactions (p-stacking). The interactions between liquid crystal host and nanotube guests are also evident from a polarizing microscopy study of the liquid crystal–isotropic phase transition in the proximity of bundles of nanotubes. The ordered liquid crystal phase is stable up to higher temperatures around the bundles than in areas without visible signs of CNTs. Conversely, the transition from the disordered isotropic phase to the liquid crystal phase on cooling always nucleates at the carbon nanotube bundles.
Scalia, G., Lagerwall, J. P. F., Haluska, M., Dettlaff-Weglikowska, U., Giesselmann, F., & Roth, S. (2006). Effect of phenyl rings in liquid crystal molecules on SWCNTs studied by Raman spectroscopy. Physica Status Solidi B, 243(13), 3238-3241. https://doi.org/10.1002/pssb.200669205