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Effect of phenyl rings in liquid crystal molecules on SWCNTs studied by Raman spectroscopy
Author(s) -
Scalia Giusy,
Lagerwall Jan P. F.,
Haluska Miroslav,
DettlaffWeglikowska Ursula,
Giesselmann Frank,
Roth Siegmar
Publication year - 2006
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200669205
Subject(s) - carbon nanotube , liquid crystal , raman spectroscopy , materials science , molecule , phase (matter) , crystal (programming language) , phase transition , chemical physics , crystallography , nanotechnology , organic chemistry , chemistry , optics , optoelectronics , condensed matter physics , physics , computer science , programming language
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 (π‐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. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)