Periodic structures on liquid-phase smectic A, nematic and isotropic free surfaces

• Anna N. Bagdinova,
• Evgeny I. Demikhov,
• Nataliya G. Borisenko,
• Sergei M. Tolokonnikov,
• Gennadii V. Mishakov and
• Andrei V. Sharkov

Beilstein J. Nanotechnol. 2018, 9, 342–352, doi:10.3762/bjnano.9.34

• isotropic liquid shows the independence of the stripe nature on the liquid crystal phase properties. The stripes disappear with increasing temperature due to the disappearance of the elastic constants on the surface. The striped formation is not a surface ordering effect like in [2][16]. On the surface

• ordering [2][21][22][23][24], the surface remains smooth and we observe only director orientation variation. Conclusion A complex study of the liquid crystal 8CB free surface in the smectic A phase was carried out. The structures of the free surface are studied using four techniques: Polarized microscopy

• amplitudes by the program MetroPro. A piece of LC display was used as a substrate (Figure 12), which provides two main advantages. First, it has a large anchoring energy for theliquid crystal director field, and second, helps to better focus at the bottom edge of the liquid crystal layer. During the

Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

• Alexej Bubnov,
• Cyril Vacek,
• Michał Czerwiński,
• Terezia Vojtylová,
• Wiktor Piecek and
• Věra Hamplová

Beilstein J. Nanotechnol. 2018, 9, 333–341, doi:10.3762/bjnano.9.33

• and for further utilisation in electro-optic devices based on the deformed helix ferroelectric effect. Keywords: ferroelectric liquid crystal; keto group; self-assembly on the nanoscale; soft ferroelectrics; submicrometre helical pitch length; Introduction The design of advanced self-assembling

Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

• Emil Petrescu and
• Cristina Cirtoaje

Beilstein J. Nanotechnol. 2018, 9, 233–241, doi:10.3762/bjnano.9.25

• Emil Petrescu Cristina Cirtoaje University Politehnica of Bucharest, Department of Physics, Splaiul Independenţei 313, 060042, Bucharest, Romania 10.3762/bjnano.9.25 Abstract The dynamic behavior of a nematic liquid crystal with added carbon nanotubes (CNTs) in an electric field was analyzed. A

• when compared to pure liquid crystal. We also noticed that the relaxation time when the field is switched off depends on how long the field was applied. It is shorter when the field is switched off immediately after application and longer when the field was applied for at least one hour. Keywords

• models have to be developed for their characterization [5][6][9][10][11]. When nanoparticles are inserted in liquid crystals, nematic molecules are attached to the particle surface due to anchoring forces. Experimental studies revealed that carbon nanotubes have a strong interaction with liquid crystal

Liquid-crystalline nanoarchitectures for tissue engineering

• Baeckkyoung Sung and
• Min-Ho Kim

Beilstein J. Nanotechnol. 2018, 9, 205–215, doi:10.3762/bjnano.9.22

• Baeckkyoung Sung Min-Ho Kim Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA Department of Biological Sciences, Kent State University, Kent, OH 44242, USA 10.3762/bjnano.9.22 Abstract Hierarchical orders are found throughout all

• levels of biosystems, from simple biopolymers, subcellular organelles, single cells, and macroscopic tissues to bulky organs. Especially, biological tissues and cells have long been known to exhibit liquid crystal (LC) orders or their structural analogues. Inspired by those native architectures, there

• nanoscale topographies [93][94]. LC elastomer scaffolds in nematic and smectic-A phases Liquid crystal elastomers (LCEs) are crosslinked 3D networks of rubber-like synthetic polymers exhibiting orientational and/or positional order [95]. Due to the tunable malleability and highly anisotropic shape change in

Dielectric properties of a bisimidazolium salt with dodecyl sulfate anion doped with carbon nanotubes

• Doina Manaila Maximean,
• Viorel Cîrcu and
• Constantin Paul Ganea

Beilstein J. Nanotechnol. 2018, 9, 164–174, doi:10.3762/bjnano.9.19

• Institute of Materials Physics, POBox MG 07, 077125 Magurele, Romania 10.3762/bjnano.9.19 Abstract A new bisimidazolium salt with dodecyl sulfate as counterion has been designed and prepared. This salt shows a SmA phase that is stable at room temperature. The new ionic liquid crystal (ILC) was

• low frequencies confirm the presence of EP. Keywords: activation energy; carbon nanotubes; dielectric spectroscopy; ionic liquid crystal; relaxation time; Introduction Ionic liquid crystals (ILCs) represent a very appealing class of materials that has found various recent applications in dye

• -sensitized solar cells, battery materials, electrochemical sensors or energy storage devices. Their interesting properties result from the combination of liquid crystal (LC) and ionic liquid (IL) properties. The recent progress and development in the field of ILCs were reviewed in several publications [1][2

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network

• Doina Manaila Maximean,
• Octavian Danila,
• Pedro L. Almeida and
• Constantin Paul Ganea

Beilstein J. Nanotechnol. 2018, 9, 155–163, doi:10.3762/bjnano.9.18

• in a similar fashion as PDLCs (polymer-dispersed liquid crystals), produced from cellulose acetate (CA) electrospun fibers deposited onto indium tin oxide coated glass and a nematic liquid crystal (E7), were studied. CA and the CA/liquid crystal composite were characterized by multiple investigation

• spectroscopy; liquid crystal; optical transmission; Introduction The widely known polymer dispersed-liquid crystals (PDLCs) are a class of liquid crystal (LC)-based electro-optical devices, formed by LC droplets dispersed in a solid polymeric matrix [1][2][3][4][5]. The optical transmission of such devices is

• deposited on indium tin oxide (ITO)-coated glass, and two such fiber-coated glass plates form a sandwich type cell, where the nematic liquid crystal (NLC) is filled in by capillarity [21][22][28]. A schematic representation of the electrospun cellulose network with the dispersed liquid crystal as well as

Nematic topological defects positionally controlled by geometry and external fields

• Pavlo Kurioz,
• Marko Kralj,
• Bryce S. Murray,
• Charles Rosenblatt and
• Samo Kralj

Beilstein J. Nanotechnol. 2018, 9, 109–118, doi:10.3762/bjnano.9.13

• TDs are various liquid crystal (LC) phases [5]. They are relatively easily accessible to various experimental methods [6] due to their unique combination of optical anisotropy and transparency, fluid character, and mechanical softness. In addition, the diversity of LC phases and structures guarantees

• confinement and/or an external electric field on topological defects in a nematic liquid crystal. We use the Landau–de Gennes approach [5] in terms of the tensor order parameter . In its eigenframe it is expressed as , where and λi are the corresponding eigenvectors and eigenvalues, respectively. We consider

Nematic liquid crystal alignment on subwavelength metal gratings

• Irina V. Kasyanova,
• Artur R. Geivandov,
• Vladimir V. Artemov,
• Maxim V. Gorkunov and
• Serguei P. Palto

Beilstein J. Nanotechnol. 2018, 9, 42–47, doi:10.3762/bjnano.9.6

• , Russia 10.3762/bjnano.9.6 Abstract We have studied the alignment of a nematic liquid crystal (LC) material on aluminum subwavelength nanogratings as a function of the period, p, and the slit width to period ratio, w/p. A method, based on Fourier analysis of the transmittance spectra of the LC grating

• have also obtained a 90° twisted LC director distribution, implying sufficiently strong azimuthal LC anchoring at the grating surface. Keywords: alignment; Fourier analysis; nematic liquid crystal; subwavelength metal grating; Introduction In the age of nanotechnology, various nanostructured

• a liquid crystal into a hybrid system is especially interesting as it can result in even more novel and interesting properties. In our recent work, we showed that liquid crystals strongly affect both the plasmon resonance and light polarization properties of subwavelength metal gratings [9

Study of the vertically aligned in-plane switching liquid crystal mode in microscale periodic electric fields

• Artur R. Geivandov,
• Mikhail I. Barnik,
• Irina V. Kasyanova and
• Serguei P. Palto

Beilstein J. Nanotechnol. 2018, 9, 11–19, doi:10.3762/bjnano.9.2

• .9.2 Abstract The ongoing interest in fast liquid crystal (LC) modes stimulated by display technology and new applications has motivated us to study in detail the in-plane switching (IPS) vertically aligned (VA) mode. We have studied how the decrease of the period of the interdigitated electrodes (down

• scale. Said electrooptical performance is further discussed below in the simulation section. As one can see from Figure 4b and Figure 4d, the relaxation time tends to increase by 10% with increasing the voltage above 10 V. We relate this effect to the increased liquid crystal volume involved into the

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

• Danil A. Petrov,
• Pavel K. Skokov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2807–2817, doi:10.3762/bjnano.8.280

• suspension of carbon nanotubes in a nematic liquid crystal. It is shown that in a magnetic field a non-uniform and two different uniform phases are possible in the suspension. The uniform phases of the suspension differ by the type of orientational coupling of nanotubes with the liquid crystal matrix (the

• first or of second order depending on the carbon nanotubes segregation intensity. Keywords: carbon nanotubes; liquid crystal; magnetic field; orientational transitions; soft coupling; Introduction In recent years suspensions of anisometric particles in liquid crystals have become of great interest for

• ferronematics depend on the segregation parameter, while for magnetized ferronematics and for LC suspensions of CNTs there is no such dependence [39][42][43]. In [44] we studied the orientational response of a magnetized ferronematic liquid crystal to magnetic and electric fields. In contrast to the above

Electro-optical characteristics of a liquid crystal cell with graphene electrodes

• Nune H. Hakobyan,
• Hakob L. Margaryan,
• Valeri K. Abrahamyan,
• Vladimir M. Aroutiounian,
• Arpi S. Dilanchian Gharghani,
• Amalya B. Kostanyan,
• Timothy D. Wilkinson and
• Nelson Tabirian

Beilstein J. Nanotechnol. 2017, 8, 2802–2806, doi:10.3762/bjnano.8.279

• Centre of Molecular Materials for Photonics and Electronics, Department of Engineering, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge, CB3 0FA, UK BEAM Co., 1300 Lee Road, Orlando, FL, 32810, USA 10.3762/bjnano.8.279 Abstract In liquid crystal devices (LCDs) the indium tin oxide (ITO) films

• ultrathin material with unique properties, e.g., high optical transparency, chemical inertness, excellent conductivity) is an excellent candidate. In this work, the electro-optical and dynamic characteristics of a liquid crystal (LC) cell with graphene and ITO transparent conducting layers are investigated

• can be successfully used as a transparent conductive layer in LC devices. Keywords: conductive layer; graphene; ITO; liquid crystal cell; optical switching time; Introduction In modern optical devices based on liquid crystals (LCs) the electro-optical control is realized using a transparent

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

• Agata Siarkowska,
• Miłosz Chychłowski,
• Daniel Budaszewski,
• Bartłomiej Jankiewicz,
• Bartosz Bartosewicz and
• Tomasz R. Woliński

Beilstein J. Nanotechnol. 2017, 8, 2790–2801, doi:10.3762/bjnano.8.278

• , Warsaw, Poland 10.3762/bjnano.8.278 Abstract Thermo- and electro-optical properties of a photonic liquid crystal fiber (PLCF) enhanced by the use of dopants have been investigated. A 6CHBT nematic liquid crystal was doped with four different concentrations of gold nanoparticles (NPs), 0.1, 0.3, 0.5 and

• 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors

• transition temperature, thus improving the thermo- and electro-optical properties of the PLCF. Keywords: fiber optics; gold nanoparticle; liquid crystal; phase transition temperature; photonic crystal fiber; Introduction Since their discovery in 1888, liquid crystals (LCs) have attracted nonstop research

Impact of titanium dioxide nanoparticles on purification and contamination of nematic liquid crystals

• Dmitrii Pavlovich Shcherbinin and
• Elena A. Konshina

Beilstein J. Nanotechnol. 2017, 8, 2766–2770, doi:10.3762/bjnano.8.275

• of adsorbing sites. Moreover, in composites with a higher NP concentration, the aggregation process is stronger. Dry nanoparticles tend to aggregate in a nematic liquid crystal matrix. We have observed this aggregation in a polarized optical microscope at a concentration of over 0.5 wt %. This

Ferrocholesteric–ferronematic transitions induced by shear flow and magnetic field

• Dmitriy V. Makarov,
• Alexander A. Novikov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2552–2561, doi:10.3762/bjnano.8.255

• composite system [1][2][3][4][5][6][7][8][9]. The physical properties of these kinds of soft condensed matter are much richer than those of the original liquid crystal materials. Depending on the type of impurity particles in liquid-crystalline colloidal systems new mechanisms for the orientation structure

• control are revealed. One of such materials is a ferroliquid crystal, a highly dispersed magnetic suspension of anisometric particles of a ferro- or ferrimagnet, in which the carrier liquid is a liquid crystal [10]. In contrast to pure liquid crystals, which are diamagnetic media with a quadrupole

• sensitive to an external magnetic field [11][12]. If the carrier medium in the ferroliquid crystal is a cholesteric liquid crystal (CLC), such a composite system is called ferrocholesteric (FC). A distinctive feature of a CLC is the presence of a supramolecular helical structure, which is very sensitive to

Nanoprofilometry study of focal conic domain structures in a liquid crystalline free surface

• Anna N. Bagdinova,
• Evgeny I. Demikhov,
• Nataliya G. Borisenko and
• Sergei M. Tolokonnikov

Beilstein J. Nanotechnol. 2017, 8, 2544–2551, doi:10.3762/bjnano.8.254

• Academy of Sciences, 53 Leninskiy Prospekt, Moscow, 119991, Russia 10.3762/bjnano.8.254 Abstract This work presents the first high-resolution nanoprofilometry study consisting of nanoscale resolution surface profile measurements and high-quality visualization of a the free surface of a liquid crystal–air

• boundary. The capabilities of this new experimental method, as applied for liquid crystal free boundaries, are discussed. The formation of focal conic domain structures at the smectic-A–air free boundary was detected and studied. Keywords: focal conic domains; free boundary; liquid crystals

• ; nanoprofilometer; smectic-A phase; Introduction The free surface of liquid crystals has been a subject of great interest since the beginning of liquid crystal science. Liquid crystalline free boundary research is very important because it shows that the intrinsic free surface properties are not influenced by the

Alternating current magnetic susceptibility of a ferronematic

• Natália Tomašovičová,
• Jozef Kováč,
• Veronika Gdovinová,
• Nándor Éber,
• Tibor Tóth-Katona,
• Jan Jadżyn and
• Peter Kopčanský

Beilstein J. Nanotechnol. 2017, 8, 2515–2520, doi:10.3762/bjnano.8.251

• phase [Tomašovičová, N. et al. Soft Matter 2016, 12, 5780–5786]. The effect has no analogue in the neat host liquid crystal. Here, we demonstrate that by doubling the concentration of the magnetic nanoparticles, the range of the dc bias magnetic field to which the ferronematic is sensitive without

• temperature with and without magnetic field have been demonstrated [15][16][17]. For the interpretation of the latter effect mean-field theoretical models have been developed [18][19]. These studies have proven that doping modifies the material properties of the host liquid crystal. The improvement of certain

• properties, such as the capability of these materials to respond to external magnetic field more efficiently, comes from the collective properties of the MNPs dispersed in the liquid crystal. In this respect, investigation of such colloidal LC systems opens up new perspectives even for applications. While

Synthesis of metal-fluoride nanoparticles supported on thermally reduced graphite oxide

• Alexa Schmitz,
• Kai Schütte,
• Vesko Ilievski,
• Juri Barthel,
• Laura Burk,
• Rolf Mülhaupt,
• Junpei Yue,
• Bernd Smarsly and
• Christoph Janiak

Beilstein J. Nanotechnol. 2017, 8, 2474–2483, doi:10.3762/bjnano.8.247

• [BMIm][FeCl4] as carbon and iron source [68]. CuCl nanoplatelets were obtained from mixtures of a Cu-containing ionic liquid crystal and 6-O-palmitoyl ascorbic acid [69]. Analysis of the MFx@TRGO nanocomposite materials by (high-resolution) transmission electron microscopy ((HR-)TEM) (Figure 1, Figures

Dynamic behavior of a nematic liquid crystal mixed with CoFe₂O₄ ferromagnetic nanoparticles in a magnetic field

• Emil Petrescu,
• Cristina Cirtoaje and
• Cristina Stan

Beilstein J. Nanotechnol. 2017, 8, 2467–2473, doi:10.3762/bjnano.8.246

• and only a small distortion angle of the liquid crystal molecular director is observed. A comparison with a previously developed theoretical model confirms this small deviation. Keywords: ferromagnetic nanoparticles; Fréedericksz transition; Introduction Currently, there is a high interest in the

• , and the analyzer axis is perpendicular to the polarizer axis (αp − αa = π/2). The optical path difference (l) induced in a cell with the thickness d can be written as: where no is the ordinary refractive index and neff is the effective refractive index. When the liquid crystal molecular director

• interaction of the liquid crystal with the applied field, the interaction of the ferromagnetic nanoparticles with the magnetic field and the LC molecules anchoring on the surface of the added particles. The deviation angle θ between the glass plates is given by: where z is the Oz coordinate of the LC

Morphology of SiO₂ films as a key factor in alignment of liquid crystals with negative dielectric anisotropy

• Volodymyr Tkachenko,
• Antigone Marino,
• Eva Otón,
• Noureddine Bennis and
• Josè Manuel Otón

Beilstein J. Nanotechnol. 2016, 7, 1743–1748, doi:10.3762/bjnano.7.167

• Madrid, Spain, Institute of Applied Physics, Military University of Technology, 00-908 Warsaw, Poland 10.3762/bjnano.7.167 Abstract Control of liquid crystal (LC) orientation using a proper SiO2 alignment layer is essential for the optimization of vertically aligned nematic (VAN) displays. With this aim

• for large deposition angles. Keywords: anisotropy; ellipsometry; liquid crystal alignment; morphology; thin film; Introduction Thin films of SiO2 and SiOx obtained by oblique deposition are commonly used as alignment layers for liquid crystal (LC) displays [1][2][3][4][5][6][7]. Several alignments

• was used, and data from [3] for an MLC95-465 (Merck) liquid crystal with Δε = −3.8. According to our data and that reported in [3], pretilt is close to zero at α < 30° and exhibit growth with α at 30° < α < 50°, while the data reported in [2] reveal growth starting from α = 60°. In the range 50° < α

Polystyrene-block-poly(ethylene oxide) copolymers as templates for stacked, spherical large-mesopore silica coatings: dependence of silica pore size on the PS/PEO ratio

• Roberto Nisticò,
• Giuliana Magnacca,
• Sushilkumar A. Jadhav and
• Dominique Scalarone

Beilstein J. Nanotechnol. 2016, 7, 1454–1460, doi:10.3762/bjnano.7.137

• critical micellar concentration, CMC) amphiphiles can spontaneously self-organize into well-defined supramolecular aggregates (host) which can be classified as normal and reverse micelles, emulsions, vesicles or liquid crystal phases and can shape or pattern other materials (guest), forming spherical

Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Gianluigi Zito,
• Teresa Cacace,
• Antigone Marino,
• José M. Otón and
• Morten A. Geday

Beilstein J. Nanotechnol. 2016, 7, 825–833, doi:10.3762/bjnano.7.74

• modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a

• system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the

• orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules. Keywords: Anchoring; carbon nanotubes; impedance; liquid crystal; negative anisotropy; Raman spectroscopy; reorientation; single-wall CNTs

Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Xabier Quintana and
• José M. Otón

Beilstein J. Nanotechnol. 2015, 6, 396–403, doi:10.3762/bjnano.6.39

• nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their

• consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low. Keywords: carbon nanotubes; Cole–Cole diagrams; impedance; liquid crystal; PEDOT:PSS

• liquid crystal, but in tilted positions through which some electric paths between the plates can be established. The presence of ionic impurities in the MWCNTs might somehow contribute to the conductivity as well; however, the extremely low concentration of CNTs makes it rather improbable that these ions

Nanobioarchitectures based on chlorophyll photopigment, artificial lipid bilayers and carbon nanotubes

• Marcela Elisabeta Barbinta-Patrascu,
• Stefan Marian Iordache,
• Ana Maria Iordache,
• Nicoleta Badea and
• Camelia Ungureanu

Beilstein J. Nanotechnol. 2014, 5, 2316–2325, doi:10.3762/bjnano.5.240

• efficient energy transfer between the Chla molecules incorporated in liposomes (ordered along SWCNTs) as a result of interaction with the carbon nanotube sidewall. These findings are in agreement with our previous studies [4][5]. As can be seen in both Figure 4 and Figure 5, the liquid crystal phase of

Synthesis of hydrophobic photoluminescent carbon nanodots by using L-tyrosine and citric acid through a thermal oxidation route

• Venkatesh Gude

Beilstein J. Nanotechnol. 2014, 5, 1513–1522, doi:10.3762/bjnano.5.164

• effective and low-cost approach. Because of the solubility of hydrophobic CNDs in organic solvents they can be used in thin film applications [34], and as a dopant in liquid crystal research [35]. Here I demonstrate a simple, effective, facile, and low cost approach to fabricate hydrophobic CNDs by using

Analysis of fluid flow around a beating artificial cilium

• Mojca Vilfan,
• Gašper Kokot,
• Andrej Vilfan,
• Natan Osterman,
• Blaž Kavčič,
• Igor Poberaj and
• Dušan Babič

Beilstein J. Nanotechnol. 2012, 3, 163–171, doi:10.3762/bjnano.3.16

• and used as mixers and pumps [5][6]. Light-driven microactuators have been manufactured using azo-doped liquid-crystal elastomers [7], although the speed of actuation that can be achieved with such a mechanism is presently too low for fluid pumping. We recently successfully manufactured self-assembled