Proceedings Article | 23 March 2016
Proc. SPIE. 9769, Emerging Liquid Crystal Technologies XI
KEYWORDS: Optical properties, Nanoparticles, Polymers, Molecules, Crystals, Composites, Liquid crystals, Molecular interactions, Dielectric spectroscopy, Nanocomposites, Liquids, Carbon nanotubes
Liquid crystals (LCs) are very attractive hosts for the organization of anisotropic nanoparticles such as carbon nanotubes
(CNTs) because of the macroscopic organization resulting in properties of nanoparticles manifest at a macroscopic scale.
Different types of LCs have demonstrated the ability to organize nanotubes, showing the generality of the approach, i.e.,
that the liquid crystallinity per se is the driving factor for the organization. Compared to standard nanotube composites
(e.g. with disordered polymer hosts) the introduction of carbon nanotubes into an LC allows not only the transfer of the
outstanding CNT properties to the macroscopic phase, providing strength and conductivity, but these properties also
become anisotropic, following the transfer of the orientational order from the LC to the CNTs. The LC molecular
structure plays an important even if ancillary role since it enters in the surface interactions, fulfilling a mediating action
between the particle and the bulk of the LC. Isolated nanotubes can be obtained by optimized dispersions at lower
concentrations and this process requires the use or development of tailored strategies like using solvents or even another
LC for pre-dispersing CNTs. Aggregates or networks can be observed in poor dispersions and at higher nanoparticle
concentrations. In those, due to surface interactions, the LC behaviour can be strongly affected with changes in phase
sequences or transition temperatures and the effect is expected to be more pronounced as the concentration of nanotubes
increases. We present preliminary investigations and observations on nanotube – LC systems based on a smectic LC
host.
