# Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience
## 4 LC-Aided-Assembly and Self-Assembly of Nanomaterials
Moreover, they can be captured by the topological defects induced by the inclusion of microparticles in nematic phases [311] (Figure 12). Such periodically organized gold nanoparticles are especially interesting for optical applications due to their intriguing SPR effects. Recently, [PERSON] et al. demonstrated that the orientation of gold nanorodswith a large range of diameters could be oriented along the direction of the linear arrays of smectic A defects, so-called smectic oily streaks. The gold nanorods self-organized into chains, increasing the density of nanorods. The gap between nanorods could be controlled through the balance between the steric repulsion and the van der Waals attraction. Furthermore, it was found that these nanorods were more likely to be trapped by the smectic dislocations with respect to ribbon-like defects. Such special microstructures of gold nanorods could lead to an electromagnetic coupling controlled by light polarization [266]. Additionally, as mentioned above, CNTs are famous for their remarkable anisotropic thermal, electrical, optical and mechanical characteristics as well as their exceptional thermal and chemical stability and have attracted interest in relation to various applications such as sensors, electronic devices, conductive and transparent films, as well as strong, light and conductive fibres. The realization of macroscopic ordered assemblies of CNTs is significant for the development of electronics, new materials and energy storage devices. In the past few years, some studies have reported on the ordered alignment and assemblies of CNTs in lyotropic LCs [322; 323; 324]. CNTs dispersed in films of polymerizable lyotropic LC surfactants can be aligned in the film thickness direction by the alignment of a suitable host mesophase under an external magnetic field [325], and filaments of uniformly aligned CNTs can be extracted from CNT-dispersed lyotropic LCs [326]. In a recent investigation, [PERSON] et al. reported that, by using photo-polymerization, a large group of SWCNT-based polymer nanocomposites was obtained from polymerizable quaternary ammonium surfactants. Efficient dispersion of CNTs within  
Figure 12: **(a)** POM images of (**I**) a 0.1 wt % Au dispersion of AuNPs in the smectic A phase showing an array of very faint lines in the direction indicated by the double-headed arrow, and (**II**) 1.0 wt % Au dispersion of AuNPs in the smectic phase between homeotropic glass slides showing an example of a curved domain where the black arrows indicate the direction of AuNP arrays. Reproduced with permission from [320]. Copyright (2012) The Royal Society of Chemistry. **(b)** Schematic illustration of a linear array of straight parallel oily streaks **(I)**; **(II)** POM image of a single array of 8 CB film on MoS\({}_{2}\). **(III)** SEM image of the MoS\({}_{2}\) substrate with gold-nanoparticle chains and **(IV)** the enlarged view. Reproduced with permission from [316]. Copyright (2012) John Wiley and Sons. **(c)** Optical microscopy image (**I**) of the dense population of toric focal conic domains (TFCDs) on Si microchannels (Inset is a schematic diagram of a silica particle trapped in the centre of a TFCD); **(II)** Confocal microscopy image of fluorescent silica particles trapped in TFCDs. Reproduced with permission from [321]. Copyright (2007) Springer Nature. **(d)** A sequence of dark-field images showing a gold-nanorod moving into a topological singularity near the microsphere **(I)** and polarizing, bright-field, dark-field microscopy images and a schematic diagram showing chains of microsphere-gold nanoparticle dimers aligned along the director **(II)**. Reproduced with permission from [311]. Copyright (2012) American Chemical Society. cylindrical micelles was observed due to the physical adsorption of the nonpolar tails of the surfactants. After photo-polymerization, the composites with SWCNTs are organized into ordered nanostructures with both lamellar and gyroid nanostructures [327].