Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

Abstract

The dynamic behavior of a nematic liquid crystal with added carbon nanotubes (CNTs) in an electric field was analyzed. A theoretical model based on elastic continuum theory was developed and the relaxation times of nematic liquid crystals with CNTs were evaluated. Experiments made with single-walled carbon nanotubes dispersed in nematic 4-cyano-4’-pentylbiphenyl (5CB) indicated a significant difference of the relaxation time when compared to pure liquid crystal. We also noticed that the relaxation time when the field is switched off depends on how long the field was applied. It is shorter when the field is switched off immediately after application and longer when the field was applied for at least one hour.

Liquid crystallinity of carbon nanotubes

“…53,54 On the other hand, CNTs, viewed as highly anisometric rigid rod-like particles, can be manipulated by electric or magnetic elds due to the dielectric and magnetic anisotropy, which is the basis for their use in modern display devices. [55][56][57][58] For all of these reasons, the interest in liquid crystallinity of CNTs is quite active. This paper is a review of the literature that deals with liquid crystallinity of CNTs and the relevant technological applications.…”

Threshold voltage decrease in a thermotropic nematic liquid crystal doped with graphene oxide flakes

“…Knowing the threshold voltage U th-EO from the EO measurements and the electric anisotropy Δε of the GO composites one can calculate the elastic constants, K 11 values, from the formula: The elastic constant is a parameter characterizing the elastic interaction between the nematic molecules. However, when GO flakes are inserted in the cell, the value of K 11 of the 5CB-GO composites also reflects the interaction between the molecules and the inserted GO flakes [41–42]. In Table 2 we see that the threshold voltage behavior of the 5CB-GO suspensions is reflected in the concentration dependence of K 11 .…”

The Influence of Single-Walled Carbon Nanotubes on the Dynamic Properties of Nematic Liquid Crystals in Magnetic Field

“…The intensity versus time plot was recorded (Figure 8), and the minima number versus time was plotted and fitted with the formula from Equation (22) using Equation (17) for the deviation angle θ m (Figure 9). The theoretical relaxation time was determined with Equation (18). Similar calculations were performed for other different magnetic fields, and the results are presented in Table 2.…”

“…After the discovery of nanomaterials and the synthesis of new nanoparticles, interest in the analysis of their physical properties increased in order to identify as many applications as possible [1][2][3][4][5][6][7][8][9][10]. Carbon-based nanoparticles, such as nanotubes, graphene, fullerene, or nanotori were analyzed both from experimental [11][12][13][14][15][16] and theoretical points of view [17][18][19][20][21][22]. Carbon nanotubes (CNTs) are the most studied due to their mechanical, electrical, optical, or magnetic properties that make them suitable for many applications in material science, nano-electronics, medicine, and other fields.…”