# Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience
## 4 LC-Aided-Assembly and Self-Assembly of Nanomaterials
Early investigations found that the liquid crystalline properties of GO dispersions are highly dependent on the concentration [165, 371] and aspect ratio of GO flakes [372]. A high concentration of GO can lead to a \"pseudo\" lamellar phase [165] and a tunable structural colour can be obtained by varying the concentration [371], while a large aspect ratio of GO flakes can efficiently decrease the critical concentration for the spontaneous formation of the nematic phase [373]. Furthermore, [PERSON] et al. found that the ability of GO to form lyotropic LCs is largely due to the polarity and the capacity of the solvents to form hydrogen bonds with GO flakes [374], while the groups of [PERSON] et al. [375] and [PERSON] et al. [376] discovered that the LC behaviour of GO dispersions was also related to the salt concentration and pH value, respectively. [PERSON] et al. [164] and [PERSON] et al. [377] showed that the macroscopic alignment of GO LC could be induced by magnetic and/or electric fields. Very recently, a systematic analysis of the electro-optical response of GO LCs under alternating fields was presented by [PERSON] et al. [378] and a shear-induced stripe assembly was reported by [PERSON] et al. [379]. Due to these intriguing physical properties, various potential applications based on GO LCs (Figure 15c-e), such as GO LC gels with \"shape memory\" effect [380], photoluminescence imaging [381], nanocomposites [382, 383, 384], sensitive strain sensors [385], transparent electrodes [386], conductive fibres [387, 388, 389, 390], multifunctional yarns [391] and membranes [392], flame-retardant nanocoatings [393], optical devices [394] and biomedical applications [395], have been anticipated and some of them have been realized. More relevant information can be found in a recent review published by [PERSON] et al. [396]. Figure 14: **(a)** Optical images of a CNT nematic LC schlieren texture. **(b)** Optical images of a dried CNTLC phase. SEM images of topological disclinations of strength +1/2 (**c**) and \(-\)1/2 are observable **(d)**. Reproduced with permission from [162]. Copyright (2003) The American Association for the Advancement of Science. **(e)** A schematic illustration of the aligning LC molecules by a CNT film. **(f)** The SEM images of the CNT alignment film on a glass substrate. Reproduced with permission from [356]. Copyright (2010) ELESVIER. **(g)** Winding drums with collected fibres. **(h)** SEM images of corresponding CNT fibres. Reproduced with permission from [368]. Copyright (2013) The American Association for the Advancement of Science. **(i)** Sketch of an optical CNT polarizer. **(j)** Schematic cell structures of a TN-LCD by the aligned CNT polarizer. Reproduced with permission from [341]. Copyright (2018) Royal Society of Chemistry. Before the conclusion of this section, it is necessary to introduce another nanomaterial that can self-assemble into cholesteric lyotropic LCs, i.e., cellulose nanocrystals (Figure 16). Cellulose nanocrystals are rod-like nanoparticles with a relatively high aspect ratio (from 10 to over 100) that can be extracted from an extensive range of materials including wood, bacteria, algae and tunicate [397; 398; 399]. Cellulose LCs have attracted much interest due to their mechanical and optical properties. The individual cellulose nanocrystal (CNC) rods are transparent across the visible spectrum and have low density and excellent mechanical strength. It is well known that suspensions of cellulose with an appropriate concentration can spontaneously form a CLC phase [159; 400; 401]. However, it is still not completely understood how the transfer of chirality from asymmetric carbons in the molecular structure of CNCs to the macroscopic scale of the LC phases occurs. A recent study by [PERSON] et al. confirmed that the mechanism of chirality transfer involves multiple steps, including a geometric effect whereby the CNCs acquire a uniformly right-handed twisted morphology and transfer this to the helical modulation of the macroscopic phase [402].