Smectic C liquid crystal growth and memory effect through surface orientation by carbon nanotubes

Abstract

A smectic C liquid crystal texture consisting of well oriented distinct local single crystals was grown using predefined orientation of single wall carbon nanotubes (SWCNTs) adsorbed on a SiOx layer deposited on a ITO treated glass surface. The orientation features of the SWCNTs were analyzed by microtexture analysis and polarized Raman spectroscopy. It was found that the surface memory effect, induced by the SWCNT/SiOx/ITO/glass surface and manifested in the preservation of the smectic C texture in the nematic phase, was many times stronger than memorization promoted by conventional SiOx/ITO/glass and ITO/glass surfaces, usually used for liquid crystal orientations. We observe surface anchoring and memorization strength reinforcement due to trapping of liquid crystal bulk charges by the SWCNTs (surface charge density increase). The SWCNT/SiOx/ITO/glass surface is found to cause a substantial enlargement of the smectic C distinct local single crystals as compared to SiOx/ITO/glass and ITO/glass surfaces. We also discuss the physical nature of the erasure activation energy components contributing to the surface memorization process. (C) 2013 Elsevier B.V. All rights reserved.