We report the synthesis and mesomorphic characterisation of two unsymmetric dimeric polycatenar mesogens (A1 and A6) incorporating an odd-membered flexible spacer and a 3,4,5-tris(hexyloxy) polycatenar terminus. The dimers were comprehensively characterised for their mesophase behaviour using differential scanning calorimetry (DSC), polarised optical microscopy (POM), and temperature-dependent small- and wide-angle X-ray diffraction (XRD). Despite combining bent molecular geometry with a multi-chain architecture, both compounds form only enantiotropic smectic phases. Compound A1 displays a single SmA phase (mesophase range 9 K), while A6 shows a SmA phase followed by a second, unidentified lamellar smectic phase of higher positional order (combined smectic range 42 K). X-ray diffraction reveals an intercalated bilayer-like SmA packing for A1 and an essentially monolayer lamellar arrangement for A6. The observation of orthogonal SmA phases in these unsymmetric polycatenar mesogens is discussed in the context of space-filling constraints and cross-sectional mismatch between the rigid core and the terminal chain volume.
The growing demand for energy-efficient building technologies has accelerated the development of adaptive smart window systems capable of regulating solar radiation and reducing cooling loads. In this study, a self-powered electro-optic smart window based on plasmonic nanomaterial-enhanced nematic liquid crystal (PNLC) was developed for adaptive thermal and optical regulation. Gold nanoparticles (AuNPs) were incorporated into the liquid crystal matrix to enhance dielectric anisotropy and electro-optic responsiveness, while an integrated thin-film photovoltaic (PV) module enabled autonomous operation. The optimised PNLC composition containing 0.05 wt% AuNPs increased dielectric anisotropy from 8.2 to 9.7, resulting in a reduced threshold voltage of approximately 2.3 V. UV - Vis - NIR spectral analysis revealed high visible transparency (similar to 75-78%) and strong near-infrared attenuation, with average NIR transmittance decreasing from approximately 79% to 35-40%, corresponding to an attenuation efficiency of nearly 50-55%. The device exhibited rapid electro-optic switching with a minimum response time of approximately 12 ms at 5.5 Vrms. Under simulated solar irradiation (200-1000 W/m(2)), the integrated PV module delivered an operating voltage of approximately 3.3 V, enabling self-powered switching. Thermal evaluation showed a surface temperature reduction from 46.7 degrees C to 30.8 degrees C and an indoor heat gain reduction of 54.6%. [GRAPHICS]
A half-shifted dual-electrode parallel-aligned fringe-field switching (PA-FFS) liquid crystal device is proposed. The effects of electrode configuration and cell gap on electric-field distribution, molecular rotation behaviour, transmittance, and response time are investigated using three-dimensional numerical simulations. The results show that thinner cell gaps provide higher transmittance, whereas thicker cell gaps exhibit more favourable PA-FFS driving characteristics with reduced interaction between the upper and lower LC layers. By redistributing and compensating the virtual-wall regions through the half-shifted electrode configuration, high transmittance can be achieved without significantly sacrificing response speed. The proposed structure therefore demonstrates strong potential for high-performance applications in photonics and virtual-reality (VR) displays that require both fast response and high optical efficiency.
Metasurfaces enable versatile electromagnetic wave manipulation through subwavelength meta-atoms, facilitating compact and multifunctional integration. Current metasurface designs mostly depend on external spatial feed structures, increasing complexity and size. This work proposes a low-profile, guided-wave-driven, liquid-crystal (LC)-based programmable metasurface with dual-band, dual-polarisation capabilities for independently controllable, dynamic beam scanning. It consists of an LC-based programmable layer fabricated by standard LCD processes and a broadband waveguide feed structure with high alignment tolerance. A complementary resonance mechanism allows meta-atoms to retain nearly identical radiating-structure dimensions across both frequency bands, overcoming traditional scaling constraints. By dynamically adjusting the LC molecular orientation, the distribution of radiated electromagnetic energy can be precisely controlled. Experimental validation demonstrates exceptional beam scanning capabilities, achieving up to +/- 75 degrees (150 degrees total) at both frequency bands, surpassing previous designs. In addition, the proposed metasurface achieves controllable near-field focusing by independently programming the aperture amplitude distribution, enabling precise energy localisation at reconfigurable focal positions. The proposed metasurface offers considerable potential for advanced next-generation mobile and satellite communication applications.
The chemically responsive properties of surface-anchored isothiocyanate-terminated (-NCS) liquid crystal compounds (LCs) have not been investigated before. Therefore, a novel series of terminal alkoxy and fluoroalkoxy tail isothiocyanate liquid crystal compounds was developed that exhibit nematic liquid crystal phase properties near ambient temperature. In order to achieve a low-melting liquid crystal compound, another series of alkoxy isothiocyanate terminal liquid crystal compounds with lateral fluorine substitution was synthesised and analysed. These lateral fluorine-substituted alkoxy isothiocyanate compounds not only lower the melting point but also show improved mesogenic behaviour compared to their non-fluorinated alkoxy isothiocyanate analogues. To investigate their potential application as chemoresponsive sensor materials, the surface anchoring behaviour of NCS-terminated LCs was investigated on metal-salt-decorated surfaces using density functional theory (DFT) calculations and experimental studies. DFT-based analysis, combined with experimental observations, revealed that mesogens bearing an isothiocyanate (-NCS) terminal group exhibit surface interactions that differ from those of mesogens with a nitrile (-CN) terminal group. We use these surface interactions to demonstrate the design of an NCS-terminated LC that responds to ozone gas.
A new series of 1,3,4-oxadiazole derivatives featuring a hockey-stick-shaped molecular architecture, composed of five interconnected phenyl rings linked via imine and ester functionalities, was successfully synthesised. The target compounds, designated as 4-(((4-(5-(4-methoxyphenyl)-1,3,4-oxadiazol-2-yl)phenyl)imino)methyl)phenyl-4-((4-alkoxyben-zylidene)amino)benzoate [Dn], were thoroughly characterised by Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (H-1 NMR), mass spectrometric analysis (GC-MS), and elemental analysis. The liquid crystalline properties of the series were investigated using polarised optical microscopy (POM) and differential scanning calorimetry (DSC). The homologues [D6-D11] exhibited a liquid crystalline behaviour, displaying both smectic A (SmA) and smectic C (SmC) mesophases across a broad temperature range, beginning at approximately 140 degrees C. A comparative analysis indicated that the insertion of the (-N=CH-Ph) moiety into the molecular core influences the mesomorphic behaviour of the synthesised derivatives relative to previously reported compounds.
A broad-focal-range liquid crystal (LC) lens array enabled by partitioned electric field modulation is proposed, featuring a simple design and low operating voltage. By combining zonal electrodes and a central electrode, the structure improves electric-field regulation in both the edge and central regions, enabling a smooth refractive-index distribution, effective focusing, and a wide focal tuning range. Simulation results show that, at 2 Vrms on the central electrode and 7.9 Vrms on the pixel electrodes, the lens achieves a near-ideal gradient refractive-index profile at a 500 mu m aperture, with a minimum focal length of 1.601 mm. In addition, the phase distribution closely matches the ideal parabolic profile, and the centre-to-edge phase difference reaches approximately 71 pi, indicating strong phase-modulation capability, low spherical aberration, and good imaging potential. Therefore, the proposed structure shows potential for applications in 2D/3D switchable displays.
Chromonic liquid crystals exhibit rich twisted configurations under cylindrical confinement, a challenging scenario for the classical Oseen-Frank theory due to its inherent energy unboundedness paradox in high-curvature settings. To overcome this limitation, we incorporate the quartic twist theory (proposed by Paparini and Virga) into the modelling of a nematic system confined between coaxial cylinders, constructing a more self-consistent continuum model. Under cylindrical symmetry, the equilibrium equation and boundary conditions of the director are derived and solved numerically. The quartic theory effectively resolves the classical energy paradox, demonstrating that axial and azimuthal anchoring conditions drive the twist angle towards 0 degrees and 90 degrees, respectively. This work establishes a reliable theoretical framework for analysing such confined systems and offers crucial insights for future experimental characterisation of anchoring strength and elastic properties.
A series of novel sexiphenyl liquid crystals featuring terminal pentyl chains and lateral alkyl/fluoro substituents were synthesised via a palladium-catalysed route using novel 2,4-dialkylphenyl boronic esters. Compounds exhibited stable nematic mesophases, with lateral substitution reducing clearing points by 300-380 degrees C versus unsubstituted sexiphenyl - with methylated compounds showing supercooling to near-ambient temperatures. Photophysical studies revealed UV-range fluorescence with quantum yields up to 94%, modulated by substituent sterics/electronics. These materials demonstrate exceptional potential for low-temperature nematic applications requiring tunable optoelectronic properties.
In this paper, the monomer containing coumarin group was introduced into the chiral liquid crystal polysiloxane system to obtain the polymers (named as CP) with photo reversibility. Then the CP polymer was reacted with the crosslinking agent containing furan ring in the presence of ZnCl2 to produce chiral liquid crystal elastomers (named as ECP). The results of Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR) showed the successful preparation of various monomers as well as polymers. We observed dramatic colour changes and Grand-jean textures of polymers using polarised optical macroscope (POM). The results of POM and selective reflection showed that both series of polymers are cholesteric liquid crystals. In the latter series, moderate crosslinking by Diels-Alder (DA) reaction can make the liquid crystal better oriented, which can maintain their wonderful liquid crystal (LC) texture and selective reflection, and at the same time, it has a certain regulation effect on the appearance of cholesteric Grand-jean blue texture. The thermal properties of two series were characterised by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA), which have excellent thermal stability. The results of X-ray diffraction (XRD) further proved the two series of polymers are cholesteric liquid crystals.
