# Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience
## 2 Modification of Physical Properties of LC Materials by Nanodopants
This improved electro-optical performance can be attributed to the higher dielectric anisotropy of the suspension, due to the extremely high permittivity and anisotropy of CNT inclusions as well as the ion-trapping effect of CNTs reducing the free ionic concentration of the solvent, which leads to an increase in the effective applied cell voltage (a reduction of electric field shielding). The inclusion of CNTs in LCs can also lead to other modifications of physical properties, such as viscosity, elastic constants and phase transition temperature, to name just a few. Very recently, [PERSON] et al. reported the enhancement of orientational order, increase of dielectric anisotropy and decrement of threshold voltage in the composite of SWCNTs and nematic LCs (3017) [214; 215] (Figure 6). However, just like ferroelectric nanoparticles, the experimental results of the CNT-LC switching behaviour are not consistent. Some authors claimed neither a decrease in threshold voltage nor an increase in dielectric anisotropy was found in respective composites. On the contrary, a higher concentration of CNTs could even increase the switching voltage [216; 217]. Another allotrope of carbon, graphene, which is a monolayer of sp2-hybridized carbon atoms arranged into a 2D honeycomb lattice, has been one of the most attractive nanomaterials since its discovery in 2004 [218]. Due to the excellent mechanical, electrical, optical, thermal and electronic properties, such as high thermal conductivity, charge mobility, mechanical strength, optical transmittance and chemical stability, graphene has been widely applied in a variety of applications such as electronics, energy storage, biomedical engineering, new composite materials, or waste water management. However, graphene is known for its notoriously poor dispersibility and solubility in solvents, organic liquids, including LCs, which greatly inhibits their use in LC composites so far, despite large efforts having been made to increase dispersibility via surface treatment and surface decoration with covalently bound mesogens. In contrast to graphene, graphene oxide (GO), obtained by treating graphite with strong oxiders, is readily dispersible in solvents, including water, due to its hydrophilic nature. In fact, in certain concentration ranges, GO actually forms a lyotropic liquid crystal in many such solvents, as well as in water. Although GO is electrically insulating, it can be converted into conducting graphene (rGO) by chemical or thermal reduction methods, at least partially regaining the conductive properties of neat graphene. So far, a series of studies have shown some improvement in the electro-optic performance of thermotropic LCs doped with graphene oxide (GO) [219; 220; 221; 222; 223; 224]. The reason for this improvement may be the coupling of electrical dipoles on the surface of the GO with the ones of mesogens and the trapping of free ionic contamination by GO. [PERSON] et al. have dispersed GO of different sizes in a nematic LC (5 CB) with a wide range of concentrations (Figure 7). They found that the LC molecules would be strongly anchored on the surface of GO flakes. As a result, the threshold voltage and elastic constants were strongly increased, while the elastically driven electro-optic off-response time decreased when increasing the concentration of GO flakes [225; 226]. Similar results in GO-doped nematic LC (E\({}_{5\text{CN}7}\)) were reported by [PERSON] et al. They found that the capacity of charge storage was expanded, while the mobility of free ions and the diffusion coefficient were significantly decreased due to the strong interaction between LC molecules and GO flakes [227]. In another publication, they also reported that GO doping would lead to an increase in the nematic-isotropic phase transition temperature, which could be shifted by changing the GO concentration [224]. Moreover, [PERSON] et al.