Special Issue "Nanomaterials in Liquid Crystals"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (31 January 2018)

Special Issue Editor

Guest Editor
Dr. Ingo Dierking

University of Manchester, School of Physics and Astronomy, Manchester, United Kingdom
Website | E-Mail
Interests: chirality effects, polymer modified liquid crystals, lyotropic graphene oxide liquid crystals, defect dynamics, nanoparticles in liquid crystals, electrophoresis in anisotropic fluids

Special Issue Information

Dear Colleagues,

This Special Issue of Nanomaterials covers the formulation, properties, theoretical aspects and applications of nanoparticles and nanostructures, dispersed in liquid crystal phases of the thermotropic and the lyotropic type, including lyotropic liquid crystal phase formation by dispersing nanomaterials in isotropic carrier fluids. The systems of nanomaterials in liquid crystals have attracted increasing interest over the last few years, due to the possibility of adding functionality to liquid crystals through properties of the dispersed particles, as well as through exploiting the self-organization of liquid crystals to form ordered structures of nanomaterials. This multidisciplinary field of research has led to a wealth of novel systems in soft condensed matter, and promises new applications in the areas of displays, optical elements, meta-materials, sensors, drug delivery, and the like.
Submission of manuscripts is invited for example, but not exclusively, on the following topic areas:

  • Methods of nanoparticle dispersion in anisotropic fluids

  • Synthesis of nanoparticle containing mesogens

  • Phases, chemical and physical properties of liquid crystal-nanomaterial dispersions

  • Microparticles and arrays of particles in liquid crystals

  • Nanotubes in liquid crystals

  • Graphene and related two-dimensional materials in liquid crystals

  • Clay doped thermotropic and inorganic liquid crystals

  • Lyotropic behaviour from colloidal particles in polar fluids

  • Computer simulations and theory

  • Applications

This list is certainly not conclusive and can be expanded. Original research papers and review articles will be considered. For reviews, please contact the Guest Editor, Dr. Ingo Dierking (ingo.dierking@manchester.ac.uk), in advance to discuss the details of the suggested contribution, in order to avoid a too extensive overlap of covered material with that of potential other authors.

Dr. Ingo Dierking
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • liquid crystal

  • ordered fluid

  • self-organisation

  • functional mesogen

  • magnetic and ferroelectric nanoparticles

  • nanotubes

  • graphene and other two-dimensional nanomaterials

  • biological nanostructures

  • colloidal dopants

Published Papers (11 papers)

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Research

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Open AccessArticle Modifying Thermal Switchability of Liquid Crystalline Nanoparticles by Alkyl Ligands Variation
Nanomaterials 2018, 8(3), 147; https://doi.org/10.3390/nano8030147
Received: 1 February 2018 / Revised: 27 February 2018 / Accepted: 1 March 2018 / Published: 7 March 2018
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Abstract
By coating plasmonic nanoparticles (NPs) with thermally responsive liquid crystals (LCs) it is possible to prepare reversibly reconfigurable plasmonic nanomaterials with prospective applications in optoelectronic devices. However, simple and versatile methods to precisely tailor properties of liquid-crystalline nanoparticles (LC NPs) are still required.
[...] Read more.
By coating plasmonic nanoparticles (NPs) with thermally responsive liquid crystals (LCs) it is possible to prepare reversibly reconfigurable plasmonic nanomaterials with prospective applications in optoelectronic devices. However, simple and versatile methods to precisely tailor properties of liquid-crystalline nanoparticles (LC NPs) are still required. Here, we report a new method for tuning structural properties of assemblies of nanoparticles grafted with a mixture of promesogenic and alkyl thiols, by varying design of the latter. As a model system, we used Ag and Au nanoparticles that were coated with three-ring promesogenic molecules and dodecanethiol ligand. These LC NPs self-assemble into switchable lamellar (Ag NPs) or tetragonal (Au NPs) aggregates, as determined with small angle X-ray diffraction and transmission electron microscopy. Reconfigurable assemblies of Au NPs with different unit cell symmetry (orthorombic) are formed if hexadecanethiol and 1H,1H,2H,2H-perfluorodecanethiol were used in the place of dodecanethiol; in the case of Ag NPs the use of 11-hydroxyundecanethiol promotes formation of a lamellar structure as in the reference system, although with substantially broader range of thermal stability (140 vs. 90 °C). Our results underline the importance of alkyl ligand functionalities in determining structural properties of liquid-crystalline nanoparticles, and, more generally, broaden the scope of synthetic tools available for tailoring properties of reversibly reconfigurable plasmonic nanomaterials. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Phase Transition-Driven Nanoparticle Assembly in Liquid Crystal Droplets
Nanomaterials 2018, 8(3), 146; https://doi.org/10.3390/nano8030146
Received: 8 February 2018 / Revised: 28 February 2018 / Accepted: 1 March 2018 / Published: 7 March 2018
Cited by 1 | PDF Full-text (3134 KB) | HTML Full-text | XML Full-text
Abstract
When nanoparticle self-assembly takes place in an anisotropic liquid crystal environment, fascinating new effects can arise. The presence of elastic anisotropy and topological defects can direct spatial organization. An important goal in nanoscience is to direct the assembly of nanoparticles over large length
[...] Read more.
When nanoparticle self-assembly takes place in an anisotropic liquid crystal environment, fascinating new effects can arise. The presence of elastic anisotropy and topological defects can direct spatial organization. An important goal in nanoscience is to direct the assembly of nanoparticles over large length scales to produce macroscopic composite materials; however, limitations on spatial ordering exist due to the inherent disorder of fluid-based methods. In this paper we demonstrate the formation of quantum dot clusters and spherical capsules suspended within spherical liquid crystal droplets as a method to position nanoparticle clusters at defined locations. Our experiments demonstrate that particle sorting at the isotropic–nematic phase front can dominate over topological defect-based assembly. Notably, we find that assembly at the nematic phase front can force nanoparticle clustering at energetically unfavorable locations in the droplets to form stable hollow capsules and fractal clusters at the droplet centers. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Kinetics of Ion-Capturing/Ion-Releasing Processes in Liquid Crystal Devices Utilizing Contaminated Nanoparticles and Alignment Films
Nanomaterials 2018, 8(2), 59; https://doi.org/10.3390/nano8020059
Received: 4 January 2018 / Revised: 17 January 2018 / Accepted: 19 January 2018 / Published: 23 January 2018
Cited by 1 | PDF Full-text (2785 KB) | HTML Full-text | XML Full-text
Abstract
Various types of nanomaterials and alignment layers are considered major components of the next generation of advanced liquid crystal devices. While the steady-state properties of ion-capturing/ion-releasing processes in liquid crystals doped with nanoparticles and sandwiched between alignment films are relatively well understood, the
[...] Read more.
Various types of nanomaterials and alignment layers are considered major components of the next generation of advanced liquid crystal devices. While the steady-state properties of ion-capturing/ion-releasing processes in liquid crystals doped with nanoparticles and sandwiched between alignment films are relatively well understood, the kinetics of these phenomena remains practically unexplored. In this paper, the time dependence of ion-capturing/ion-releasing processes in liquid crystal cells utilizing contaminated nanoparticles and alignment layers is analyzed. The ionic contamination of both nanodopants and alignment films governs the switching between ion-capturing and ion-releasing regimes. The time dependence (both monotonous and non-monotonous) of these processes is characterized by time constants originated from the presence of nanoparticles and films, respectively. These time constants depend on the ion adsorption/ion desorption parameters and can be tuned by changing the concentration of nanoparticles, their size, and the cell thickness. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Improvement of Image Sticking in Liquid Crystal Display Doped with γ-Fe2O3 Nanoparticles
Nanomaterials 2018, 8(1), 5; https://doi.org/10.3390/nano8010005
Received: 25 October 2017 / Revised: 12 December 2017 / Accepted: 19 December 2017 / Published: 24 December 2017
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Abstract
Image sticking in thin film transistor-liquid crystal displays (TFT-LCD) is related to the dielectric property of liquid crystal (LC) material. Low threshold value TFT LC materials have a weak stability and the free ions in them will be increased because of their own
[...] Read more.
Image sticking in thin film transistor-liquid crystal displays (TFT-LCD) is related to the dielectric property of liquid crystal (LC) material. Low threshold value TFT LC materials have a weak stability and the free ions in them will be increased because of their own decomposition. In this study, the property of TFT LC material MAT-09-1284 doped with γ-Fe2O3 nanoparticles was investigated. The capacitances of parallel-aligned nematic LC cells and vertically aligned nematic LC cells with different doping concentrations were measured at different temperatures and frequencies. The dielectric constants perpendicular and parallel to long axis of the LC molecules ε and ε//, as well as the dielectric anisotropy Δε, were obtained. The dynamic responses and the direct current threshold voltages in parallel-aligned nematic LC cells for different doping concentrations were also measured. Although the dielectric anisotropy Δε decreased gradually with increasing temperature and frequency at the certain frequency and temperature in LC state for each concentration, the doping concentration of γ-Fe2O3 nanoparticles less than or equal to 0.145 wt % should be selected for maintaining dynamic response and decreasing free ions. This study has some guiding significance for improving the image sticking in TFT-LCD. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Templated Sphere Phase Liquid Crystals for Tunable Random Lasing
Nanomaterials 2017, 7(11), 392; https://doi.org/10.3390/nano7110392
Received: 30 September 2017 / Revised: 3 November 2017 / Accepted: 7 November 2017 / Published: 15 November 2017
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Abstract
A sphere phase liquid crystal (SPLC) composed of three-dimensional twist structures with disclinations among them exists between isotropic phase and blue phase in a very narrow temperature range, about several degrees centigrade. A low concentration polymer template is applied to improve the thermal
[...] Read more.
A sphere phase liquid crystal (SPLC) composed of three-dimensional twist structures with disclinations among them exists between isotropic phase and blue phase in a very narrow temperature range, about several degrees centigrade. A low concentration polymer template is applied to improve the thermal stability of SPLCs and broadens the temperature range to more than 448 K. By template processing, a wavelength tunable random lasing is demonstrated with dye doped SPLC. With different polymer concentrations, the reconstructed SPLC random lasing may achieve more than 40 nm wavelength continuous shifting by electric field modulation. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Magnetic Nanoparticle-Assisted Tunable Optical Patterns from Spherical Cholesteric Liquid Crystal Bragg Reflectors
Nanomaterials 2017, 7(11), 376; https://doi.org/10.3390/nano7110376
Received: 30 September 2017 / Revised: 25 October 2017 / Accepted: 2 November 2017 / Published: 8 November 2017
Cited by 1 | PDF Full-text (2049 KB) | HTML Full-text | XML Full-text
Abstract
Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these
[...] Read more.
Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidics. Water-soluble magnetofluid with Fe3O4 nanoparticles incorporated in the inner aqueous core of CLC shells is responsible for the non-invasive transportable capability. With the aid of an external magnetic field, the reflection interactions between neighboring microshells and microdroplets were identified by varying the mutual distance in a group of magnetically transportable and unmovable spherical CLC structures. The temperature-dependent optical reflection patterns were investigated in close-packed hexagonal arrangements of seven CLC microdroplets and microshells with inverse helicity handedness. Moreover, we demonstrated that the magnetic field-assisted assembly of microshells array into geometric figures of uppercase English letters “L” and “C” was successfully achieved. We hope that these findings can provide good application prospects for security pattern designs. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Dynamic Response of Graphitic Flakes in Nematic Liquid Crystals: Confinement and Host Effect
Nanomaterials 2017, 7(9), 250; https://doi.org/10.3390/nano7090250
Received: 22 July 2017 / Revised: 24 August 2017 / Accepted: 30 August 2017 / Published: 1 September 2017
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Abstract
Electric field-induced reorientation of suspended graphitic (GP) flakes and its relaxation back to the original state in a nematic liquid crystal (NLC) host are of interest not only in academia, but also in industrial applications, such as polarizer-free and optical film-free displays, and
[...] Read more.
Electric field-induced reorientation of suspended graphitic (GP) flakes and its relaxation back to the original state in a nematic liquid crystal (NLC) host are of interest not only in academia, but also in industrial applications, such as polarizer-free and optical film-free displays, and electro-optic light modulators. As the phenomenon has been demonstrated by thorough observation, the detailed study of the physical properties of the host NLC (the magnitude of dielectric anisotropy, elastic constants, and rotational viscosity), the size of the GP flakes, and cell thickness, are urgently required to be explored and investigated. Here, we demonstrate that the response time of GP flakes reorientation associated with an NLC host can be effectively enhanced by controlling the physical properties. In a vertical field-on state, higher dielectric anisotropy and higher elasticity of NLC give rise to quicker reorientation of the GP flakes (switching from planar to vertical alignment) due to the field-induced coupling effect of interfacial Maxwell-Wagner polarization and NLC reorientation. In a field off-state, lower rotational viscosity of NLC and lower cell thickness can help to reduce the decay time of GP flakes reoriented from vertical to planar alignment. This is mainly attributed to strong coupling between GP flakes and NLC originating from the strong π-π interaction between benzene rings in the honeycomb-like graphene structure and in NLC molecules. The high-uniformity of reoriented GP flakes exhibits a possibility of new light modulation with a relatively faster response time in the switching process and, thus, it can show potential application in field-induced memory and modulation devices. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle Synthesis of Distinct Iron Oxide Nanomaterial Shapes Using Lyotropic Liquid Crystal Solvents
Nanomaterials 2017, 7(8), 211; https://doi.org/10.3390/nano7080211
Received: 29 June 2017 / Revised: 28 July 2017 / Accepted: 30 July 2017 / Published: 2 August 2017
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Abstract
A room temperature reduction-hydrolysis of Fe(III) precursors such as FeCl3 or Fe(acac)3 in various lyotropic liquid crystal phases (lamellar, hexagonal columnar, or micellar) formed by a range of ionic or neutral surfactants in H2O is shown to be an
[...] Read more.
A room temperature reduction-hydrolysis of Fe(III) precursors such as FeCl3 or Fe(acac)3 in various lyotropic liquid crystal phases (lamellar, hexagonal columnar, or micellar) formed by a range of ionic or neutral surfactants in H2O is shown to be an effective and mild approach for the preparation of iron oxide (IO) nanomaterials with several morphologies (shapes and dimensions), such as extended thin nanosheets with lateral dimensions of several hundred nanometers as well as smaller nanoflakes and nanodiscs in the tens of nanometers size regime. We will discuss the role of the used surfactants and lyotropic liquid crystal phases as well as the shape and size differences depending upon when and how the resulting nanomaterials were isolated from the reaction mixture. The presented synthetic methodology using lyotropic liquid crystal solvents should be widely applicable to several other transition metal oxides for which the described reduction-hydrolysis reaction sequence is a suitable pathway to obtain nanoscale particles. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Review

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Open AccessFeature PaperReview Ferroelectric Nanoparticles in Liquid Crystals: Recent Progress and Current Challenges
Nanomaterials 2017, 7(11), 361; https://doi.org/10.3390/nano7110361
Received: 7 October 2017 / Revised: 24 October 2017 / Accepted: 24 October 2017 / Published: 1 November 2017
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Abstract
The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of
[...] Read more.
The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of ferroelectric nanoparticle/liquid crystal colloids. By compiling a great variety of experimental data and discussing it in the framework of existing theoretical models, both scientific and technological challenges of this rapidly developing field of liquid crystal nanoscience are identified. They can be broadly categorized into the following groups: (i) the control of the size, shape, and the ferroelectricity of nanoparticles; (ii) the production of a stable and aggregate-free dispersion of relatively small (~10 nm) ferroelectric nanoparticles in liquid crystals; (iii) the selection of liquid crystal materials the most suitable for the dispersion of nanoparticles; (iv) the choice of appropriate experimental procedures and control measurements to characterize liquid crystals doped with ferroelectric nanoparticles; and (v) the development and/or modification of theoretical and computational models to account for the complexity of the system under study. Possible ways to overcome the identified challenges along with future research directions are also discussed. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessFeature PaperReview Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials
Nanomaterials 2017, 7(10), 305; https://doi.org/10.3390/nano7100305
Received: 11 August 2017 / Revised: 14 September 2017 / Accepted: 14 September 2017 / Published: 1 October 2017
Cited by 2 | PDF Full-text (6642 KB) | HTML Full-text | XML Full-text | Correction
Abstract
Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an
[...] Read more.
Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Other

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Open AccessCorrection Correction: Dierking, Ingo and Al-Zangana, Shakhawan. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials. Nanomaterials 2017, 7, 305
Nanomaterials 2018, 8(1), 45; https://doi.org/10.3390/nano8010045
Received: 27 December 2017 / Revised: 2 January 2018 / Accepted: 2 January 2018 / Published: 15 January 2018
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Abstract
Due to an oversight during production, the authors wish to make the following correction to reference [65] of this paper [...]
Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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