Towards Efficient Dispersion of Carbon Nanotubes in Thermotropic Liquid Crystals

Abstract

Motivated by numerous recent reports indicating attractive properties of composite materials of carbon nanotubes (CNTs) and liquid crystals (LCs) and a lack of research aimed at optimizing such composites, the process of dispersing CNTs in thermotropic LCs is systematically studied. LC hosts can perform comparably or even better than the best known organic solvents for CNTs such as N‐methyl pyrrolidone (NMP), provided that the dispersion process and choice of LC material are optimized. The chemical structure of the molecules in the LC is very important; variations in core as well as in terminal alkyl chain influence the result. Several observations moreover indicate that the anisotropic nematic phase, aligning the nanotubes in the matrix, per se stabilizes the dispersion compared to a host that is isotropic and thus yields random tube orientation. The chemical and physical phenomena governing the preparation of the dispersion and its stability are identified, taking into account enthalpic, entropic, as well as kinetic factors. This allows a guideline on how to best design and prepare CNT–LC composites to be sketched, following which tailored development of new LCs may take the advanced functional material that CNT–LC composites comprise to the stage of commercial application.

Controlling the crystalline three-dimensional order in bulk materials by single-wall carbon nanotubes

“…In light of the latter, CNTs are suitable candidates for emerging nanotechnological applications [16][17][18][19][20][21] . In fact, numerous ways of dispersing CNTs in matrices such as surfactants 22 , polymers [23][24][25] , biopolymers [26][27][28] , supramolecular organic gels 29,30 and liquid crystals [31][32][33][34][35][36] were meant to order structures. The use of any of the aforementioned matrices has resulted in hybrid materials, in which both morphology and order are mainly controlled by the matrix components, while CNTs lack any significant role.…”

Preparation and characteristics of conducting polymer-coated multiwalled carbon nanotubes for a gas sensor

“…A sample chemical stability for resistance to acidic and high-temperature conditions [21][22][23][24]. The bottleneck that limits the use of CNTs as a gas-sensing material is their insufficient sensitivity to low concentrations of target gases.…”

Effect of gold nano-particles on switch-on voltage and relaxation frequency of nematic liquid crystal cell

“…The effect of CNTs in the twisted nematic (TN)-LC device has been studied and found that the CNT doped cell reduces the switch-on voltage and improves the response time. 7 Effect of gold nano-particles (GNPs) on the memory of ferroelectric LC material has been reported and it was found that the memory is enhanced remarkably due to electric field induced charge transfer from LC molecules to the GNPs and the stabilization of helix deformation of deformed helix FLC material, which occurs on the application of electric field beyond a critical value. 9 The influence of gold nano-rods (GNRs) on the electro-optic and dielectric properties of the ferroelectric liquid crystals (FLCs) has also been investigated.…”

“…The electro-optical characteristics of LC material, such as, Guest-host effect, bi-stability and field induced director axes re-orientation and switch-on voltage are important factors 1,2 for the display application. Recently, there has been enormous amount of research for the enhancement of electro-optical properties of LC materials by means of doping of metallic nano-particles (NPs), [3][4][5] carbon nano-tubes (CNTs) 6,7 and quantum dots 8 into the LC cell. The effect of CNTs in the twisted nematic (TN)-LC device has been studied and found that the CNT doped cell reduces the switch-on voltage and improves the response time.…”