Cуспензії вуглецевих нанотрубок у рідкому кристалі за сприянням органічно модифікованих лапонітових нанопластинок

We present a simple and effective approach for dispersion of carbon nanotubes (CNTs) into liquid crystals (LCs), suitable for a wide range of CNT concentrations (60.1 wt.%). It consists in doping of LC+CNT suspensions with Laponite, which shows high affinity to the nanotubes. The organo-modified Laponite platelets surround CNTs and hamper their aggregation. At the same time, they do not hinder orientational ordering of CNTs imposed by LC matrix. This approach avoids problems of direct organo-modification of CNTs, associated with worsening of their unique properties. The increased dispersion degree results in drastic changes in dielectric and electro-optical characteristics of the suspensions. Dispersing and insulating effects of the Laponite platelets on CNTs lead to the absence of classical percolation of conductivity, linear growth of dielectric constant with CNT concentration, as well as reduction of Frederiks threshold and significant growth of contrast ratio of the E7+CNTs suspensions

Electro-optical memory of a nematic liquid crystal doped by multi-walled carbon nanotubes

A pronounced irreversible electro-optical response (memory effect) has been recently observed for nematic liquid crystal (LC) EBBA doped by multi-walled carbon nanotubes (MWCNTs) near the percolation threshold of the MWCNTs (0.02÷0.05 wt. %). It is caused by irreversible homeotropic-to-planar reorientation of LC in an electric field. This feature is explained by electro-hydrodynamically stimulated dispergation of MWCNTs in LC and by the formation of a percolation MWCNT network which acts as a spatially distributed surface stabilizing the planar state of the LC. This mechanism is confirmed by the absence of memory in the EBBA/MWCNT composites, whose original structure is fixed by a polymer. The observed effect suggests new operation modes for the memory type and bistable LC devices, as well as a method for <i>in situ</i> dispergation of carbon nanotubes in LC cells

Electro-optical properties of a liquid crystalline colloidal solution of rod shaped V2O5 nanoparticles and carbon nanotubes in an alternating current electric field

We study the liquid crystalline phase behaviour of the two-component aqueous colloidal suspensions of multiwalled carbon nanotubes (MWCNTs) and rod-like vanadium pentoxide (V2O5) nanoparticles. The phase diagram features a stable nematic phase in a wide range of concentration of solid components. The oriented nematic phase of the two-component suspension was exposed to the action of alternating current electric field. A variation in MWCNTs concentration within 0.01–0.51 wt.% demonstrates a significant increase in the optical response of the system to the applied electric field