Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

Dierking, Ingo; Al-Zangana, Shakhawan

doi:10.3390/nano7100305

Cited by 108 publications

(80 citation statements)

References 155 publications

(178 reference statements)

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“…In this scenario, amphiphilic molecules must arrange themselves to simultaneously minimize the steric hinderance and maximizing their polar-polar (and apolar-apolar) interactions [34][35][36]. Due to their low abundance in the systems, solvent molecules end up being confined in regions with the same polarity, while the amphiphiles form strong templating cages.…”

Section: Liquid Crystalline Nanostructuresmentioning

confidence: 99%

Self-Assembly of Organic Nanomaterials and Biomaterials: The Bottom-Up Approach for Functional Nanostructures Formation and Advanced Applications

et al. 2020

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In this paper, we survey recent advances in the self-assembly processes of novel functional platforms for nanomaterials and biomaterials applications. We provide an organized overview, by analyzing the main factors that influence the formation of organic nanostructured systems, while putting into evidence the main challenges, limitations and emerging approaches in the various fields of nanotechology and biotechnology. We outline how the building blocks properties, the mutual and cooperative interactions, as well as the initial spatial configuration (and environment conditions) play a fundamental role in the construction of efficient nanostructured materials with desired functional properties. The insertion of functional endgroups (such as polymers, peptides or DNA) within the nanostructured units has enormously increased the complexity of morphologies and functions that can be designed in the fabrication of bio-inspired materials capable of mimicking biological activity. However, unwanted or uncontrollable effects originating from unexpected thermodynamic perturbations or complex cooperative interactions interfere at the molecular level with the designed assembly process. Correction and harmonization of unwanted processes is one of the major challenges of the next decades and requires a deeper knowledge and understanding of the key factors that drive the formation of nanomaterials. Self-assembly of nanomaterials still remains a central topic of current research located at the interface between material science and engineering, biotechnology and nanomedicine, and it will continue to stimulate the renewed interest of biologist, physicists and materials engineers by combining the principles of molecular self-assembly with the concept of supramolecular chemistry.

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Section: Liquid Crystalline Nanostructuresmentioning

confidence: 99%

Self-Assembly of Organic Nanomaterials and Biomaterials: The Bottom-Up Approach for Functional Nanostructures Formation and Advanced Applications

et al. 2020

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“…Normally, one can split LCs into two typical categories, i.e., thermotropic LCs and lyotropic LCs [7][8][9][10]. Thermotropic LCs are usually further distinguished according to the shape of their constituent molecules, being called calamitic for rod-like, discotic for disk-like and sanidic for brickor lath-like molecules (Figure 1a) [11].…”

Section: Introductionmentioning

confidence: 99%

“…Another interesting research field of LC-nanomaterial technology that is worthwhile to discuss is the self-assembly of lyotropic LCs composed of 1-or 2D anisotropic nanomaterials [3,7]. This topic has been investigated from time to time as people have realized that suspensions of anisodiametric nanomaterials can form LC phases, even at a very low concentration, due to Bernal's seminal work on suspensions of tobacco mosaic virus [155] and Onsager's theory of the excluded volume mechanism [156].…”

Section: Introductionmentioning

confidence: 99%

Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience

2019

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The research field of liquid crystals and their applications is recently changing from being largely focused on display applications and optical shutter elements in various fields, to quite novel and diverse applications in the area of nanotechnology and nanoscience. Functional nanoparticles have recently been used to a significant extent to modify the physical properties of liquid crystals by the addition of ferroelectric and magnetic particles of different shapes, such as arbitrary and spherical, rods, wires and discs. Also, particles influencing optical properties are increasingly popular, such as quantum dots, plasmonic, semiconductors and metamaterials. The self-organization of liquid crystals is exploited to order templates and orient nanoparticles. Similarly, nanoparticles such as rods, nanotubes and graphene oxide are shown to form lyotropic liquid crystal phases in the presence of isotropic host solvents. These effects lead to a wealth of novel applications, many of which will be reviewed in this publication. the observation of chirality from achiral molecules, resulting from sterically induced packing of the bent-core mesogens [10], such as ferroelectricity or the formation of helical superstructures in the B7 phase [14]. Thermotropic LCs are commonly constituted by single organic entities or mixtures thereof, which exhibit various mesophases at different temperatures or pressures [15], illustrated in Figure 1b. As the temperature rises, a typical thermotropic LC passes through higher ordered phases, also called soft crystals, the hexatic smectic phases with positional order as well as bond orientational order, through the fluid smectic phases (SmC and SmA), which exhibit both positional and orientational order, and finally to the nematic phase (N) with purely orientational order, into the isotropic phase. The number of different phases observed depends on the chemical composition, symmetry and order of the LC molecules. About 25 different thermotropic phases are known to date, and they are still increasing in number. Appl. Sci. 2019, 9, x FOR PEER REVIEW 2 of 47 unique effects of the observation of chirality from achiral molecules, resulting from sterically induced packing of the bent-core mesogens [10], such as ferroelectricity or the formation of helical superstructures in the B7 phase [14]. Thermotropic LCs are commonly constituted by single organic entities or mixtures thereof, which exhibit various mesophases at different temperatures or pressures [15], illustrated in Figure 1b. As the temperature rises, a typical thermotropic LC passes through higher ordered phases, also called soft crystals, the hexatic smectic phases with positional order as well as bond orientational order, through the fluid smectic phases (SmC and SmA), which exhibit both positional and orientational order, and finally to the nematic phase (N) with purely orientational order, into the isotropic phase. The number of different phases observed depends on the chemical composition, symmetry and order of the LC molecules. About...

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“…Amphiphilic lyotropic liquid crystals are also the most common type of all liquid crystals, since their lamellae form the basic structure of biological cell membranes [27,29]. Colloids of anisodiametric particles in liquid solvents can also possess orientational ordering at sufficiently high concentrations [30]. Though the structures that are aligning are quite different to the case of amphiphiles, they are nevertheless referred to as lyotropic liquid crystals.…”

Section: Colloidal Liquid Crystals Of Graphene Oxidementioning

confidence: 99%

Lyotropic Liquid Crystals from Colloidal Suspensions of Graphene Oxide

Draude

Dierking

2019

Crystals

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Lyotropic liquid crystals from colloidal particles have been known for more than a century, but have attracted a revived interest over the last few years. This is due to the developments in nanoscience and nanotechnology, where the liquid crystal order can be exploited to orient and reorient the anisotropic colloids, thus enabling, increasing and switching the preferential properties of the nanoparticles. In particular, carbon-based colloids like carbon nanotubes and graphene/graphene-oxide have increasingly been studied with respect to their lyotropic liquid crystalline properties over the recent years. We critically review aspects of lyotropic graphene oxide liquid crystal with respect to properties and behavior which seem to be generally established, but also discuss those effects that are largely unfamiliar so far, or as of yet of controversial experimental or theoretical outcome. Crystals 2019, 9, 455 2 of 20 easy to handle, because graphene is largely insoluble in nearly all liquid solvents. This is very different for graphene-oxide (GO) which exhibits different functional groups at the edges and the plane of the graphene oxide sheets, and is readily soluble in many solvents, including water, which is a significant advantage for environmentally friendly applications (Figure 1b). At certain concentrations, roughly > 0.1-1 wt%, GO often exhibits very stable lyotropic nematic phases [11][12][13]. One of the interesting aspects of GO liquid crystals is the possibility of self-organized and self-ordered systems of graphene oxide. This order can then easily be manipulated by application of external stimuli, such as boundary conditions, mechanical shear, but possibly also electric and magnetic fields. After obtaining a certain directional order one could wash away or evaporate the solvent, leaving an ordered GO structure, which may even be reduced chemically or through heat application to produce reduced graphene oxide (rGO), which displays some of the originally desirable graphene properties. Lyotropic graphene oxide liquid crystals are thus of immense interest for nanotechnology and its applications. There have been several review articles on the properties of GO liquid crystals [14][15][16]. In this paper we want to give a short critical account of what is known, what is not yet known, and what are the controversial questions with regards to graphene oxide liquid crystals. Effects of flake size and solvent will be discussed, alignment, addition of salts and polymers, as well as electro-optic properties, and electric and magnetic field effects. Graphene and Graphene OxidePristine graphene is a two-dimensional hexagonal lattice of sp 2 hybridized carbon with a basis of two, giving rise to a honeycomb structure [10]. Graphene oxide is a very different material to graphene. Graphene is often obtained by mechanical exfoliation of graphite (the so-called Scotch Tape ® method) or grown by chemical vapor deposition. On the other hand, graphite that has undergone treatment to become graphite oxide readily exfoliates ...

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Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

Cited by 108 publications

References 155 publications

Self-Assembly of Organic Nanomaterials and Biomaterials: The Bottom-Up Approach for Functional Nanostructures Formation and Advanced Applications

Self-Assembly of Organic Nanomaterials and Biomaterials: The Bottom-Up Approach for Functional Nanostructures Formation and Advanced Applications

Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience

Lyotropic Liquid Crystals from Colloidal Suspensions of Graphene Oxide

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