# Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience
## 1 Introduction
(**b**) A typical illustration of different thermotropic LC phases observed on heating from crystalline state. Reproduced with permission from [7]. Copyright (2017) MDPI. spherical or rod-like micelles, leading to the formation of the hexagonal phase, cubic phase or lamellar phase. Nevertheless, the solute component of a lyotropic LC need not always be molecular in nature, but may also consist of much larger (solid) particles with anisotropic shapes. It can also be of colloidal size [7], as we will discuss further in Section 3. Such materials would then be known as inorganic liquid crystals, LC clays, but also nanotubes, graphene oxide or biological structures such as viruses (Figure 3). The fact that the director of LCs, which is often equivalent to the optic axis of the material, is easily influenced by a variety of external stimuli such as mechanical, magnetic, electric, or optic fields, as well as temperature, makes liquid crystals attractive to both the industry and academia [6; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26], as exemplified by the $100 billion industry built around displays and large-screen, flat-panel consumer electronics. Due to the great achievement in displays since the 1970s, LCs are one of the most popular materials around the world [27]. However, with the rapid development and impressive advantages of organic light-emitting displays (OLEDs), there is some competition emerging. Over the last decade, more and more scientists have moved their attention away from display materials to a diversity of new fields--for instance, new optical devices, telecommunication, information storage, energy conservation, elastomer robots, sensors, biotechnologies, nano-/micromanipulation, just to name a few [28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45]. These new fields can be quite different from displays and more stimulating due to their novelty, leading to a new era for LCs, materials design and technology. Figure 2: A typical lyotropic LC phase diagram of amphiphilic molecules dissolved in a solvent. Cubic phases may be observed at different positions in the phase diagram. At very high concentrations, the inverse phases are located. Reproduced with permission from [7]. Copyright (2017) MDPI. At the same time, revolutionary developments have been made in the fields of nanotechnology and nanoscience, leading to the birth of a series of novel nanomaterials [10; 47; 48; 49; 50; 51; 52; 53; 54; 55]. These nanostructured materials, whose size in at least one dimension is in the range from 1 nm to 100 nm, have gained a wealth of academic and industrial attention due to their size-dependent electronic, optical, magnetic, and chemical properties, which are significantly different from those of bulk materials as well as from individual atoms or molecules [55; 56; 57; 58; 59; 60; 61; 62]. These nanostructured materials have been extensively applied in nearly every field of science from energy, optics, computing to catalysis, biosciences and medical sciences [48; 63; 64; 65]. Undoubtedly, when these novel nanometre-scale structures encounter liquid crystals, a highly interesting and unique synergy will be observed, leading to an abundance of entirely new and potential applications [2; 8; 42; 66; 67; 68; 69; 70]. The addition of nanomaterials to a LC material produces a composite or colloidal dispersion [71; 72]. The new materials are expected to behave differently from their individual components (nanomaterials and LCs) both on the microscopic as well as the macroscopic scale [63; 64; 65; 66; 67; 68; 69; 70; 71; 72; 73; 74; 75; 76; 77]. There are three basic objectives to making a LC-nanomaterial composite system: (i) to modify the primary physical or chemical properties of the pristine LCs [78; 79; 80]; (ii) manipulating and ordering nanomaterials in LCs to modify the properties of nanomaterials [81]; and (iii) to obtain additional functionalities that are available from neither the LCs nor the nanomaterials in their intrinsic states [82].