Dispersions of carbon nanotubes in cholesteric liquid crystals with photoactive components

Optical transmission and selective reflection data are reported for dispersions of single walled carbon nanotubes (SWCNT) in cholesteric liquid crystals comprising a mixture of cholesterol esters and azoxy nematic ZhK-440. The optical density was shown to be essentially non-linear with SWCNT concentration, with a minimum ascribed to formation of "stacked" aggregates of nanotubes. The location of this minimum, as well as the selective reflection maximum (helical pitch), are sensitive to partially reversible UV-induced trans-cis-trans isomerisation effects. The UV-controlled helical pitch variation was shown to be only slightly affected by introduction of carbon nanotubes. Application prospects of such materials in optoelectronic devices are considered.