Improvement of the relaxation time and the order parameter of nematic liquid crystal using a hybrid alignment mixture of carbon nanotube and polyimide

Abstract

We examined the electrooptical properties of a nematic liquid crystal (LC) sample whose substrates were coated with a mixture of carbon nanotube (CNT) and polyimide (PI). The relaxation time of the sample coated with 1.5 wt. % CNT mixture was about 35% reduced compared to the pure polyimide sample. The elastic constant and the order parameter of the CNT-mixture sample were increased and the fast relaxation of LC could be approximated to the mean-field theory. We found the CNT-mixed polyimide formed more smooth surface than the pure PI from atomic force microscopy images, indicating the increased order parameter is related to the smooth surface topology of the CNT-polyimide mixture.

Orientational and electro-optical properties of liquid crystal aligned with a directly spinnable carbon nanotube web

“…[1] In addition, the π-π interaction between the CNT web and the LC molecules might contribute to the uniform LC orientation. [9] A question can be raised why the POM image of the rubbed CNT cell in Figure 2(f) is darker than the pure SE7492 sample in spite of the similar Δn. This is due to the light absorption of the CNT web.…”

“…[7][8][9][10][11][12] For instance, Kuo et al reported a homeotropic orientation of LC using the polyhedral oligomeric silsesquioxane (POSS) nanoparticles. [7] Hwang et al demonstrated a continuous control of the pretilt angle of LC using functionalised POSS.…”

“…[8] Lee et al showed that small amount of carbon nanotube (CNT) fibres dispersed in PI induced a uniform surface topography and a faster turn-off time. [9] Russell et al showed that the films of aligned CNT bundles deposited on glass could align the LC molecules. [10] Moreover, Fu et al [11] and Jian et al [12] found that 10-cm-wide webs of aligned CNTs formed by drawing directly from specially grown 'forests' or arrays could function both as the alignment layer and electrode.…”

P‐92: Orientational Ordering of Nematic Liquid Crystal Aligned with a Directly Spinnable Carbon Nanotube Web

“…In recent years, the approaches using a small amount of nanoparticles doped into LC or a polyimide (PI) have drawn a great deal of attention [1][2][3][4][5]. For instance, Kuo et al reported a vertical alignment of LC using the polyhedral oligomeric silsequioxane (POSS) nanoparticles [1].…”

“…For instance, Kuo et al reported a vertical alignment of LC using the polyhedral oligomeric silsequioxane (POSS) nanoparticles [1]. Lee et al showed that a mixture of small amount of multi-wall carbon-nanotube (CNT) and PI induced a uniform surface topography and a faster relaxation of LC molecules [2]. Russell et al obtained a planar alignment using the film of aligned CNT bundles deposited on glass [3].…”