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Surface reconstruction has always been a pain point in the study of short-chain perfluoroalkyl acrylate polymers, and how to maintain the balance between environmental protection and good performance is the key issue. We exploited the high efficiency and selectivity of the reaction between the isophorone di-isocyanate group and the hydroxyl group, and the rigid cyclohexane structure contained in their molecule to efficiently prepare a series of novel fluoro acrylate monomers (IFAM) containing rigid cyclohexane as mesogenic core and their homopolymers (PIFAM) with different lengths of short-chain perfluoroalkyl side chains. Their structures, liquid crystal behavior, thermal properties, surface chemical compositions, surface morphologies, and hydrophobicity were characterized and comparatively studied by FTIR, NMR, XRD, POM, DSC, TGA, XPS, AFM, and static/dynamic contact angle tester and dodecafluoroheptyl methacrylate (DFMA) and its homopolymer as a contrast. The results demonstrated that both the synthesized monomers and homopolymers possessed the expected chemical structures with thermotropic liquid crystalline behavior. Furthermore, the thermal stability and hydrophobicity of the polymers increased with the extension of the fluorocarbon chain length. The incorporation of the mesocrystalline motif and appropriate length of fluoroalkyl tails in the PIFAM polymers would enhance hydrophobic stability, as it promoted the crystallinity of the side chains and limited the structural rearrangement of the fluorocarbon chains. This study offers a straightforward method for synthesizing fluoro acrylate polymers with stable surface properties, highlighting their potential application in hydrophobic coatings. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis and characterisation of an anthraquinone-based discotic liquid crystal (DLC), AFLC-14-doped ceric phosphate, a novel composite ion exchanger which exhibits superior ion exchange properties. The incorporation of AFLC-14 betwixt the layers of ceric phosphate aims to strengthen the material’s thermal property, adsorption capacity, and disinfectant properties along with ion-exchange capabilities. The reported material underwent extensive physico-chemical characterisation using various analytical techniques, including FTIR, UV-vis spectrophotometry, XRD analysis, SEM imaging, TGA/DTA studies and elemental investigation. Additionally, ion-exchange characteristics were investigated, encompassing ion-exchange capacity, concentration dependency, thermal property, adsorption studies for alkaline earth and heavy/transition metal ions, and binary separation experiments. Our findings reveal that the incorporation of a DLC betwixt ceric phosphate matrix significantly improves the exchanger’s overall performance. Notably, the hybrid ion exchanger exhibits remarkable selectivity for mercury (II) ions, indicating its potential for selective ion removal applications in environmental remediation and water purification processes. [ABSTRACT FROM AUTHOR]

We report on a set of experiments directed to a problem of microparticles interaction with a disclination in a nematic liquid crystal matrix. The idea of the study consists in the visualization of the disclination by filling it with particles efficiently scattering light. A θ-cell possessing a topological defect of undetermined twist which can capture micro-sized objects was exploited. The results obtained for samples of different shape can be used as for the understanding of the nature of self-assembling clusters, as for the practical goal of increasing the visibility of a disclination being a dynamic object sensitive to temperature and other external factors and able to move the trapped particles. [ABSTRACT FROM AUTHOR]

Liquid crystal monomers (LCMs), prized for their unique optical properties, are ubiquitous in a range of electronic products. However, their growing use and disposal have led to a continuous influx of LCMs into the environment as contaminants. This review synthesizes information on the sources, environmental distribution, migration, transformation, toxicity, and risks associated with LCMs. It also introduces predictions of adverse outcomes related to protein binding potential, grounded in the Adverse Outcome Pathway framework. It was pointed out for the first time that the fundamental causes of LCM contamination were informal recycling and dismantling patterns, coupled with obsolete liquid crystal processing technologies. The significant variability among different types of LCMs in distribution patterns, environmental persistence, bioaccumulation, mobility, and toxicity were emphasized. Notably, fluorinated LCMs, especially fluorobiphenyls, which posed the greatest comprehensive risk, were prone to accumulate in atmospheric dust. Our molecular docking results showed that monomers containing cyano groups, which had greater direct toxicity, carcinogenic, and mutagenic risk, also exhibited strong binding affinity, underscoring the need for priority control strategies. Additionally, this review delved into LCM exposure pathways and the heightened toxicity during degradation and metabolism. It emphasizes the importance of risk assessments for LCMs and identifies key scientific questions that require further investigation. The insights provided a scientific foundation for preventing environmental risks and promoting green chemical alternatives related to LCMs. [ABSTRACT FROM AUTHOR]

A new separation technology, three-phase crystallization (TPC), was utilized to purify acrylic acid (AA) from a binary liquid mixture comprising AA and propionic acid (PA). The solid–liquid equilibrium data of AA/PA mixture reported in the literature were adopted to recover the activity coefficients of the liquid mixture; and, subsequently, the vapor–liquid equilibrium conditions of AA/PA mixture were predicted using Raoult's law and the Wilson equations for the recovered activity coefficients. The reported solid–liquid equilibrium data and the predicted vapor–liquid equilibrium conditions were coupled to determine the three-phase transformation conditions of AA/PA mixture, which were employed to conduct the batch TPC experiments. Upon conclusion of the TPC, the yield and purity were measured to estimate the amount of the AA crystals and volume of the liquid mixture retained in the overall final product, respectively. [ABSTRACT FROM AUTHOR]

Laguerre–Gaussian (LG) beams with a spiral phase (optical vortex), which feature orbital angular momenta, and vector beams (VBs) with an axially symmetric spatial polarization distribution exhibit properties different from those of conventional Gaussian beam. In this article, we introduce LG beams and VBs. Next, we explain the generation of LG beams and VBs using liquid-crystal devices. Subsequently, we report the super-resolution observation of biological samples and our observation of a PNLC (Polymer network liquid crystal) network structure using a laser scanning microscope, which comprises a liquid crystal LG-VB generator. Finally, we discuss the conservation of spiral beams and their application to optical wireless communication. [ABSTRACT FROM AUTHOR]

Smart windows are attractive considering their contribution to energy efficiency and privacy protection. However, the achievement of flexible reverse-mode film with good stability and well electro-optical performance for smart windows remains a fascinating challenge in recent years. Herein, we reported a low-driving-voltage, high-stability flexible reverse-mode liquid crystal/polymer composite film for energy-efficient smart windows by the formation of polymer structure with a polyhedral oligomeric silsesquioxane (POSS) core and strong epoxy resin as chains. The experimental results suggested that the polymer can not only stabilise the planar state of the cholesteric liquid crystal in the zero field but also provide enough support to the continuous liquid crystal phase on flexible substrate. Besides, the optimised optical device could be fully driven at 30 V (lower than safety voltage, 36 V) and keep contrast ratio of 100. Moreover, the flexible film showed outstanding optical regulation performance and excellent cycle stability under electric field. The strategy used in this research would open new doors for the development of energy-efficient smart windows in buildings. [ABSTRACT FROM AUTHOR]

Liquid crystals with their unique ordered mesophases and anisotropic physical properties, such as optical, magnetic and dielectric anisotropy, have found wide opto-electronic applications, especially liquid crystal displays (LCDs) in digital electronic devices, such as smart phones, tablets, laptops, TVs, etc. Liquid crystals incorporating 2,5-disubstituted pyrimidine rings in their aromatic cores are often used in commercial LCDs. They are also critical building blocks of liquid crystalline organic semiconductors designed for use in novel organic electronic devices, such as organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), sensors, etc. This review will focus specifically on pyrimidine-based liquid crystals, such as calamitic, bent, discotic, taper-shaped, small molecules, oligomers and polymers. It will highlight the relationships between molecular structure and liquid crystalline behaviour, i.e. mesomorphism of relevance to organic and opto-electronic applications. It will highlight the development, optimisation and innovation of liquid crystalline materials containing pyrimidine rings, thereby stimulating the potential for new structural design and applications, such as sensors, flexible electronics, 4D printing and subsequently opening up completely new markets for these advanced functional materials. [ABSTRACT FROM AUTHOR]

Polymer Dispersed Liquid Crystal (PDLC) films are attracting increasing attention as versatile and innovative material for use in electrical switching and flexible devices. This paper investigates the effect of a Poly(methyl methacrylate (PMMA) nanospun membrane system doped with SiO2 nanoparticles on the electro-optical properties and transmittance/voltage slopes of thiol- and acrylate-based PDLC films. Experimental samples were prepared for testing by adding mixtures of liquid crystals and crosslinkers in different proportions to liquid crystal cassettes doped with PMMA/SiO2 nanospun membranes. The size of the polymer mesh was found to influence all parameters of PDLC. The phase separation process, which determines the morphology and electro-optical properties of PDLC films, is directly affected by the doping of different components of PMMA/SiO2. The doping of the PMMA/SiO2 system resulted in improved optoelectronic properties of PDLC films, significantly enhanced weathering resistance, and increased the degree of intelligent regulation of the transmittance of PDLC films. Thus, by developing PDLC-doped reticulated nanofibre films with faster response times and better electro-optical properties, the potential for technological applications of PDLC-based devices in optical windows, displays, energy storage and flexible devices can be significantly enhanced. [ABSTRACT FROM AUTHOR]

Smart windows have become increasingly popular due to their ability to provide privacy protection, energy efficiency, and user control. Therefore, this technology has a wide range of applications in various fields such as construction, automotive, aviation, and renewable energy. However, commercialisation faces two significant challenges due to the slow response speed and low transmittance. This work demonstrates a 5CB-doped polymer-stabilised sphere-phase liquid crystal (PS-SPLC) smart window with sub-millisecond response time, which can be switched between transparent and scattering states by an electric field. The transmittance exceeds 90% when the voltage is on in the visible light range. This 5CB-doped PS-SPLC smart window has the potential to usher in a new era of smart window research. [ABSTRACT FROM AUTHOR]

Azobenzene photoalignment (PA) material SD1 is of significance in fabricating planar liquid crystals (LC) elements because of their high sensitivity and rewritability. Herein, the influence of exposure energy density on the rewriting process of SD1 is studied via the analysis of the alignment quality of the LC layer. Based on such unique erasability of SD1, a multi-exposure approach of preparing the spin-decoupled LC devices is presented experimentally, confirming multiple phase structures can be integrated into a single component. the relative weight for the two kinds of orientation structures can be controlled by exposed energy density, successfully enabling the intensity-editable holographic functionality. Our work might offer an entirely new perspective on studying the rewriting mechanism of SD1 stuff and open an effective avenue for developing the LC-based integrated apparatus. [ABSTRACT FROM AUTHOR]

The fabrication of liquid crystalline elastomer (LCE) with reversible deformation is promising for development of intelligent materials and equipment. Preparing new liquid crystalline monomer (LCM) and developing novel LCE structures are crucial for the fabrication of advanced LCE. Herein, we design and synthesis a series of side-on nematic epoxy LCM, and then fabricate corresponding LCE with micropillar array via photoinitiated polymerisation of a magnetic induced oriented LCMs with soft lithography patterned structures. 1H NMR, 13C NMR, COSY, FTIR and MS spectra confirm the structures of the LCMs. DSC and POM results demonstrate that the LCMs are nematic liquid crystals. SEM, OM, and POM observations indicate the successful fabrication of LCE micropillars that exhibit reversible contraction and extension during heating and cooling cycles. In addition, the thermal induced reversible deformation of the LCE micropillars is closely related to the structure of the LCM. By using the same method, functional LCE with multi-fold gratings are prepared by using the multi-fold gratings master mask during the fabrication process, providing a material foundation for the construction of intelligent surfaces that can selectively diffract light under external thermal stimuli. [ABSTRACT FROM AUTHOR]

In this paper, we study the influence of the protein Bovine Serum Albumin (BSA) on the dielectric properties of liquid crystals (LCs) such as 4-cyano-4-pentyl biphenyl (5CB) and Octyl-4-biphenylcarbonitrile (8CB). Studying the effect of proteins on the dielectric properties of LC is essential for both fundamental research and practical applications in material science, biomedical engineering, biotechnology, and optoelectronic devices. It helps understand the protein behaviour on the surface of LCs, which offers an opportunity to develop novel sensing platforms. A polarising optical microscope (POM) was used to examine the correlation between textures formed by LCs interacting with different concentrations of BSA. In the dielectric studies, dielectric parameters such as impedance (Z), real (Z') and imaginary (Z") parts of the impedance, and the tangential loss (tan δ) were measured. The investigation involved analysing relaxation times using the collected data, revealing distinct behaviours between 5CB and 8CB liquid crystals. Bode and Nyquist's plots were constructed and analysed to investigate the changes LCs undergo while interacting with BSA. An equivalent electrical circuit (EEC) was constructed using Bode and Nyquist data, from which circuit element values were successfully extracted. The results obtained from the POM studies and the interferences drawn from the EIS can help enhance the performance of protein-based liquid crystal devices. [ABSTRACT FROM AUTHOR]

Liquid crystal physical gels (LCPG) with a 3D network structure show considerable promise as novel functional materials with a great impact on scientific and practical applications. LCPGs are not characterised by high hardness and high strength, but this mild nature is capable of forming dynamic supramolecular structures with the self-assembly ability of various non-covalent bonds such as hydrogen bonding, π-π stacking, and van der Waals forces. In addition to anisotropic changes under optical and electrical stimulation, it enables to be one of the candidates for display devices. When the isotropic-anisotropic transition temperature of LCPG solution (TIA) is higher than the sol-gel transition temperature of gel molecules (TSG), the gelation can anchor the orientation of liquid crystal molecules to achieve the alteration of transparency and scattering of the film. In this paper, reverse mode LCPG films with high contrast, low driving voltage, and excellent cycle life were prepared using oriented liquid crystal cassettes and LCPG solutions, it also focused on the effects of chiral compounds (S)-octan-2-yl 4-((4-(hexyloxy)benzoyl)oxy)benzoate (S811) and gel 1,3:2,4-bis-0-(3,4-dimethylbenzylidene)sorbitol (DMDBS) content on electro-optical properties of LCPG films as well as the different functions of TIA and TSG on film orientation. [ABSTRACT FROM AUTHOR]

The theory based on numerical study of the system of hydrodynamic equations, which includes the director motion, shows that under the influence of crossed electric E and magnetic B fields, the director reorients in such a way that the transient symmetric quasi-periodic patterns may arise in microsized nematic volumes if the corresponding distortion mode has the fastest response and thus suppresses all other modes, including uniform ones. It has been shown that there is a threshold value of the amplitude of the thermal fluctuations of the director over the microsized nematic film which provides the nonuniform rotation mode rather than the uniform one, whereas the lower values of the amplitude dominate the uniform mode. [ABSTRACT FROM AUTHOR]

We investigate the nematic (N) to twist-bend nematic (NTB) phase transition in binary mixtures of a symmetric liquid crystal dimer (CB7CB) and a calamitic bi-phenyl mesogen (7OCB). As the molar concentration of 7OCB increases, both the Iso–N and N–NTB transition temperatures decrease gradually, consequently, the width of the nematic phase above the NTB phase can suitably be varied from ~12 K to 46 K. Notably, as the nematic range expands, there is a remarkable reduction in transitional entropy, eventually approaching negligible or zero values. Additionally, the heat capacity peak and the phase shift disappear when transitional entropy reaches zero. This behaviour diverges from typical N–SmA and N–SmC phase transitions, where transitional entropy decreases near the tricritical point but the heat capacity peak persists. Our findings indicate a finite positive δ(∆n) across all concentrations at the N–NTB phase transition, suggesting a gradually weakening first-order nature. This contrasts with theoretical predictions of a second-order N–NTB phase transition, as our experimental data consistently supports a first-order nature. The self-consistent mean-field Landau Model successfully validates our experimental data, establishing the universal first-order nature of the N–NTB phase transition, with experimental entropy values in good agreement with theoretical prediction. [ABSTRACT FROM AUTHOR]

Dopamine (DA) is an important neurotransmitter, playing significant roles in various psychological and physiological process of human body. However, the development of a simple, highly sensitive and cost-effective method for DA detection is still challenging. In this study, we report a simple, sensitive and label-free liquid crystal (LC)-based aptasensor for DA detection using a LC-aqueous interface with hexadecyltrimethylammonium bromide (CTAB) as a mediator. In the presence of DA, the specific DA-aptamer binding would weaken the electrostatic interaction between the aptamer and CTAB. This, in turn, promotes the assembly of CTAB at LC-aqueous interface and consequently induces a planar-to-homeotropic anchoring transition of LCs at the interface, which allows the detection of DA under polarized optical microscope (POM) with high sensitivity and specificity. By analysing the variation in dark pixel ratio in POM images of LC films, quantitative detection of DA can be achieved. The results show a linear detection range for DA from 10 pM to 1 μM with a detection limit as low as 2.51 pM (S/N = 3). Moreover, the feasibility of the LC-based aptasensor for DA detection in urine samples has been also validated. [ABSTRACT FROM AUTHOR]

Structurally coloured responsive materials provide an interesting avenue for the development of autonomous temperature regulating window films. One interesting class of such thermochromic materials is cholesteric liquid crystals. However, cholesteric liquid crystals have rarely been applied in coatings for smart window applications. In this work, we report the synthesis of endcapped cholesteric liquid crystal oligomers and its application as near-infrared thermochromic coatings for windows. Two isomerically pure monoacrylate endcapping molecules and its isomeric mixture are synthesised. The molecules are used to synthesise a variety of endcapped cholesteric liquid crystal oligomers to study the effect of the isomeric purity on the thermochromic properties of the coatings. It is found that while the oligomers are almost identical in composition and phase behaviour, only one isomer produces a clear transparent coating, highlighting the significance of minute isomeric differences. Remarkably, the thermochromic behaviour of the coatings for all oligomers is the same. The best performing oligomer is able to reversibly blueshift by 250 nanometres when heated from room temperature to 100°C, opening the way of cholesteric liquid crystals for use in temperature regulating window films. [ABSTRACT FROM AUTHOR]

The main goal is to study the structural and dielectric characteristics of advanced composite materials based on ionic metal alkanoates with various types of nanoparticles. The matrix Cd+2(C7H15COO)−2 formed as a result of the reaction of cadmium with the carboxylate groups of alkanoate (C7H15COO)−2 is used for the synthesis of nanoparticles. At room temperature, the matrix of the ionic crystalline material represents multilayer structure with each layer thickness of 1.8 nm. However, when heated in the temperature range from 100 °C to 180 °C, the matrix undergoes a phase transition into the liquid crystalline smectic A phase, preserved after cooling to room temperature. This transition opens up possibilities for the synthesis of carbon and gold nanoparticles. The temperature treatments of the matrix allow to control of the size and shape of nanoparticles during synthesis and create highly stable nanocomposites. The structural features and dielectric properties of these nanocomposites are studied using transmission electron microscopy, enabling to determine of the sizes of nanoparticles and their dispersion and impedance spectroscopy, respectively. Dielectric properties of nanocomposite materials were studied at different temperatures corresponding to two material phases. We carried out an analysis of the dielectric characteristics of the pure matrix in comparison with nanocomposite materials, containing carbon and gold nanoparticles to identify the role of the nanoparticles. Based on our experimental data, we proposed a model to explain the charge transfer process, taking into account relaxation processes and polarization of nanocomposite materials. [ABSTRACT FROM AUTHOR]

A nano-structured surface containing an Au nano-island film is used to fabricate hybrid liquid crystal (HLC) cells. HLCs are characterized by faster response times. The dynamic holographic technique is applied to make the conversion of the laser pulse shape by using HLCs. From a comparative analysis of experimental results with theoretical modeling of a dynamic process, the time constants of the dynamic grating recording and relaxation have been determined. [ABSTRACT FROM AUTHOR]

This study focuses on the development and characterization of molecularly imprinted thin films in the absence and presence of a liquid crystal monomer, as well as the evaluation of these materials for recognition of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Molecular imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were prepared by using two functional monomers, n-butylmethacrylate (BMA) and liquid crystalline (LC) 6-(4-cyanophenyl-4′phenoxy) hexyl acrylate (A6OCB). The resulting (MIPs) and (NIPs) materials were characterized by infrared spectroscopy (FTIR), Raman spectroscopy, polarized optical microscopy (POM), and atomic force microscopy (AFM). The entire monomer consumption, as well as the successful loading and extraction of the 2,4-D molecules, were validated by FTIR and Raman analyses. POM and AFM characterization revealed that the percentage of liquid crystal influenced the distribution of the liquid crystal domains and that the MIP films exhibited remarkable porosity. The experimental results revealed that the MIP films had a substantially higher adsorption capacity toward 2,4-D than the NIP materials and that increasing the liquid crystal content increased the adsorption capacity of both the MIP and NIP films. The selectivity tests in the presence of phenoxyacetic acid (POAc) showed that the MIP films exhibited higher affinity for 2,4-D than for the POAc. [ABSTRACT FROM AUTHOR]

Six members of the 1,ω-bis(4-cyanobiphenyl-4′-yl) alkanes are reported and referred to as CBnCB in which n = 1, 15, 16, 17, 19 and 20 and indicates the number of methylene units in the spacer separating the two cyanobiphenyl units. The behaviour of CB3CB is revisited. The temperature dependence of the refractive indices, optical birefringence and dielectric permittivities measured in the nematic, N, phase for selected homologues are reported. The dimers with n ≥ 15 showed an enantiotropic N phase, and for the odd members the twist-bend nematic, NTB, phase was observed. CB3CB shows a direct NTB-isotropic, I, transition, whereas for CB1CB a virtual NTB-I transition is found. The temperature dependence of the bend elastic constant, K33, measured in the oblique helicoidal cholesteric state formed by mixtures of CBnCB with a chiral additive S811, shows strong non-monotonous behaviour with a deep minimum near the transition point to the NTB phase. The minimum value of ${K_{33}}$ K 33 decreases as n increases. The long even members of the CBnCB series show similar values of TNI to their odd-membered counterparts, but their estimated values of TNTBN are considerably lower. This is attributed to molecular shape and its effect on K33. [ABSTRACT FROM AUTHOR]

5CB liquid crystal (LC) is a well-studied material for a variety of applications due to its orientational ordering and viscosity. LCs mostly suffer from ionic impurities which can be filtered using metal oxide nanoparticles. Beyond this conventional role of TiO2 nanoparticles (NPs) in ionic impurity filtration in LCs, we have employed a new methodology to improve the planar orientation of 5CB molecules by depositing a thin layer of NPs on either side of the ITO electrode. The 5CB LC exhibits a typical birefringent schlieren texture; however, the presence of TiO2 layer alters the molecular orientation. On the TiO2 surface, the 5CB LC molecules showed schlieren defect points characterised by both twofold (s = $ \pm $ ± 1/2) and fourfold (s = $ \pm $ ± 1) brush-like structures. The change in texture and lowering of dielectric permittivity might be attributed to the change in the pretilt angle of 5CB molecules owing to the mutual interactions between 5CB and TiO2 layer. Remarkably, the 5CB LC within the TiO2-coated cell attains the isotropic phase at lower temperature as compared to the cells coated with polyimide SE-130. The underlying mechanism for coarsening kinetics in the 5CB is elucidated using the Lifshitz-Slyozov-Wagner (LSW) theory. [ABSTRACT FROM AUTHOR]

Selective fluorination is a well-established technique to tailor and improve many of the physical properties of liquid crystals. Cyanobiphenyls are among the best-known and understood thermotropic liquid crystals and have served admirably as a testbed for structural modifications that can eventually be extended to other classes of liquid crystals. As such, and expanding on our earlier work, in the present study of the alkoxycyanobiphenyl M series, the individual tail sites of both 4'-(butoxy)[1,1'-biphenyl]-4-carbonitrile (M12) and 4'-(pentyloxy)[1,1'-biphenyl]-4-carbonitrile (M15) were selectively monofluorinated in order to examine the influence on the phase behavior. These fluorinated compounds were synthesized using epoxidation, regioselective epoxide opening and deoxyfluorination chemistry. In all the fluorinated compounds in both series a monotropic nematic phase was found in the cooling cycle. It was observed that as the fluorine atom on the tail moves closer to the core, the compounds exhibited a metastable room temperature nematic mesophase, but recrystallization invariably occurred. Both enantiomers of 4'-(2-fluorobutoxy)[1,1'-biphenyl]-4-carbonitrile were synthesized in high enantiomeric purity by regioselective opening of chiral epoxide intermediates followed by deoxyfluorination, as established by chiral high-performance liquid chromatography, and their phase behaviors were determined. Moreover, the average dipole moments of the synthesized fluorine substituted derivatives were also calculated. [ABSTRACT FROM AUTHOR]

We synthesised selenium-linked liquid crystal dimers and examined their phase behaviour to determine the effects of chalcogen linkage and spacer length on the formation of a twist-bend nematic (NTB) phase. Two new homologous series of nonsymmetric selenoether- and ether- or thioether-linked cyanobiphenyl-based dimers (CBSenOCB and CBSenSCB, respectively) comprising an alkyl spacer chain with a carbon number (n) of 3, 5, 6, 7, 9, and 11 were developed. We also synthesised n = 6 and 11 of previously reported symmetrically selenoether-linked CBSenSeCB homologues. Conventional nematic (N) and NTB phases were observed for nearly all odd-n CBSenSeCB, CBSenOCB, and CBSenSCB dimers. The phase transition behaviours of the three homologous series were compared with those of the known symmetric ether-linked CBOnOCB, thioether-linked CBSnSCB, and asymmetric thioether- and ether-linked CBSnOCB dimers. Replacing ether with thioether or selenoether resulted in lower LC phase-transition temperatures, particularly for selenoether. Single-crystal structural analyses revealed that CBS3SCB and CBSe3SeCB exhibited folded U-shaped molecular shapes that were bent more than the V-shapes of CBOnOCB (n = 3 and 5) and CBS5SCB. In addition, thioether and selenoether linkages rendered the molecular forms of odd-spacer dimers in the crystals more bent. [ABSTRACT FROM AUTHOR]

Some recent studies on liquid crystal dispersions have shown that biphasic states of a mesogenic system, in which one phase appears as droplets or inclusions in the matrix of the other, are a convenient means of generating topological defects (elastic dipoles, quadrupoles and their assemblies), and studying their varied interactions with external fields. This review aims to highlight a few of the notable findings from such less common colloids. Among the aspects covered here are (i) the Fank-Pryce geometry of NTB droplets evidenced by radial disclinations of strength k = 2, (ii) defect-generated complex shapes of twist-bend nematic (NTB) drops growing in the nematic (N) matrix, (iii) existence of metastable intermediate states between the elastic dipole and quadrupole geometries, (iv) evolution of equilibrium parabolic focal conic (PFC) networks in NTB drops in the isotropic environment, (v) flexoelectric oscillations of hyperbolic hedgehogs and transport of elastic dipoles in the N matrix, (vii) flexoelectric dimensional changes in PFC domains, (viii) Induced charge electrophoretic motion of NTB drops in the isotropic medium, accompanied by vortical electroconvection within the drops, and (v) Lehmann thermo-mechanical rotation of twisted bipolar N drops. [ABSTRACT FROM AUTHOR]

Giant cells of characean algae provide an excellent platform for testing different techniques to explore cytoplasmic streaming, electrophysiological behaviour, intercellular communication, and drug delivery methods. In this study, we successfully applied nematic emulsions based on 5CB to visualise the shuttle flow in cells' cytoplasm. Additionally, we demonstrate the compatibility of the liquid crystal material with the intracellular environment. [ABSTRACT FROM AUTHOR]

Thermotropic liquid crystals have been known from 1888, but have experienced little practical application or commercial usage up until the 1970s, when they were sandwiched between conducting glass plates and an electric field was applied. Their response to the field precipitously demonstrated an opportunity for creating and changing visible images using low voltage electric fields. At a similar time, the world was about to experience the invention of integrated electrical circuits, or CHIPs as they became known. The strange connection between solid-state semi-conductor electronics and the imagery provided via semi-fluid non-conducting organic materials meant that visual communication devices became a possibility, provided that there was an associated revolution in the design of nematogens as no suitable research or commercial materials were available at that time. With the synthesis of cyanobiphenyls by chemists at the University of Hull in 1972, within two years the picture dramatically changed. This is the story of the birth 5CB. [ABSTRACT FROM AUTHOR]

Just as nematic liquid crystals are widespread in display technology, a small number of building blocks find widespread use in the design and synthesis of liquid crystalline materials. This review explores the intricate relationship between the molecular structure of thermotropic liquid crystals (LCs) and their phase behaviour, emphasising the role of specific structural fragments in determining LC properties. We also detail into the impact of non-conventional building blocks on LC properties by comparing families of materials differentiated by only a single structural variation, allowing us to probe the extent to which deviations from traditional structures can maintain liquid crystallinity. This comprehensive overview not only underscores the importance of specific molecular fragments in LC design but also opens avenues for the innovative use of non-traditional building blocks in the development of new LC materials. Just as the ubiquity of 1,4-disubstituted benzene rings has its genesis (partly) in the extremely robust and predictable synthesis of such systems through cross-coupling chemistry; we consider that, the rapid progress in coupling sp3 fragments, coupled with the growing availability of suitable building blocks, makes the inclusion of said fragments ever more practical and attractive for use in liquid crystalline systems. [ABSTRACT FROM AUTHOR]

We report an experimental work on the liquid crystal dimer 1",7'-bis(4-cyanobiphenyl-4'-yl) heptane (CB7CB) confined to Anopore membranes. We have studied the behaviour of the dielectric relaxation modes in the isotropic (I), nematic (N) and twist-bend nematic (NTB) phases by broadband dielectric spectroscopy and compared to the results of the bulk sample. We have found that the strength of the components of the static dielectric permittivity for bulk and confined samples diminishes when cooling but, once in the NTB phase, those of the confined CB7CB tend to decrease in a slower rate compared to the ones of bulk CB7CB. This work is meant to play a humble tribute to the first report on a cyanobiphenyl-based LC in its 50th anniversary. [ABSTRACT FROM AUTHOR]

A new series of liquid crystal dimers, 4-cyano-1,3-phenylene bis(4-((4'-cyano-[1,1'−biphenyl]-n-yl)oxy)alkanoate), has been synthesised and confirmed for their molecular structure using standard spectroscopic techniques. Thermal behaviour is assessed using optical polarising microscope (OPM), differential scanning calorimetry (DSC), and X-ray diffraction. Interestingly, all the dimers exhibit a super-cooled nematic phase without crystallisation during cooling cycles. These molecules self-assemble with head-on aggregation assessed by UV–Visible absorption spectra, and they also have a distinct fluorescence characteristic. A super-cooled nematogens self-assemble into head-on aggregation with a fluorescence property. Moreover, the materials were studied for their fluorescence properties and proved to be fluorescence active, making them excellent candidates to be used in designing photo-responsive optical sensor devices. [ABSTRACT FROM AUTHOR]

Liquid crystal-forming cyanobiphenyls are truly extraordinary molecules that have had an enormous impact on liquid crystal research and applications since they were first synthesised. This impact is, on the one hand, due to the exceptionally convenient physical properties of the main characters, 5CB and 8CB, allowing easy experiments at room temperature, as well as their commercial availability at reasonable cost. On the other hand, the cyanobiphenyl chemical structure leads to some quite peculiar characteristics in terms of organisation at the molecular scale, which are sometimes well recognised and even utilised, but often the awareness of these peculiarities is not strong. This perspective article reviews the use of cyanobiphenyls in making liquid crystal shells and liquid crystal core fibres, in sensing, as a medium for simultaneously aligning and dispersing carbon nanotubes, and as highly useful solvents for reactive mesogens that can be polymerised into anisotropic networks. This choice is very much motivated by how cyanobiphenyls have impacted our group's research throughout the years, which is the basis for the examples I provide. Nevertheless, I believe they serve well to illustrate the immense usefulness of cyanobiphenyls in innovating research and applications related to liquid crystals. [ABSTRACT FROM AUTHOR]

Graphene oxide is hydrophilic due to its oxygen functionality, making it easy to disperse in liquid crystalline media. The nanocomposites of graphene oxide and reduced graphene oxide have been prepared in a nematic liquid crystal. Results reveal rising transition temperatures, enthalpies, and order parameters for graphene oxide dispersed nanocomposites. UV-Vis spectroscopy results show an increase of the optical band gap for graphene oxide whereas decrease for reduced graphene oxide dispersed system. Impedance spectroscopy is used for the determination of various parameters such as permittivity, dielectric anisotropy, conductivity, relaxation frequency and activation energy. Results show that the dielectric anisotropy is increased for graphene oxide dispersed nanocomposite, however, reduced graphene oxide dispersed system demonstrates the opposite property. Relaxation frequency has increased for graphene oxide dispersed system while unchanged for reduced graphene oxide dispersed system. Conductivity of reduced graphene oxide dispersed nanocomposite has increased by three orders of magnitude but for graphene oxide dispersed system, it has decreased as compared to that of the pure sample. We observed decrease in threshold voltage, elastic constant, and rotational viscosity for both GO/rGO dispersed systems. The outcome for the graphene oxide dispersed nanocomposite looks to be more effective due to the system's enhanced molecular polarisability. [ABSTRACT FROM AUTHOR]

Liquid-crystalline mechanically interlocked molecules have been prepared from a clickable pillar[5]arene-containing [2]rotaxane building block incorporating ethynylated stoppers and dendritic mesogenic subunits of generation 0, 1 and 2 under copper-catalysed alkyne-azide cycloaddition conditions. The liquid-crystalline properties of the resulting pillar[5]arene-based rotaxanes bearing 4, 8 and 16 peripheral cyanobiphenyl units have been investigated and compared to those of corresponding model compounds lacking the macrocyclic component. [ABSTRACT FROM AUTHOR]

Cyanobiphenyls (CBs) are a class of molecules with unique properties that make them highly versatile in various fields. Their anisotropic nature, low viscosity, and sensitivity to external stimuli make them ideal for applications in display technology, photonic devices, sensors, and in tunable antennas. In this article, we present the design and simulation of a 5CB LC antenna for tunable microwave frequency applications due to its fast response time and low dielectric loss than other CB materials. The proposed antenna contains two glass substrates with an air gap of 0.004 mm between them. The lower glass contains a size of 20 × 15 mm2, while the upper glass contains a size of 13 × 15 mm2. The proposed antenna produces two bands when there is an air gap between the glass plates; three bands when diodes are used for the radiating patch; and four bands when 5CB LC material is introduced between the glass plates as a dielectric medium. The same structure produces various frequency bands, which is a notable advantage compared to the existing state of the art. All the results shown in this manuscript were simulated and measured with the body of data available from the literature. [ABSTRACT FROM AUTHOR]

A novel application of thermotropic liquid crystal (LC) 5CB in an optical aptasensor for the sensitive detection of amoxycillin (AMOX) antibiotic has been reported. In the studied system, the glass substrates were treated with dimethyloctadecyl [3–(trimethoxysilyl) propyl] ammonium chloride (DMOAP) and an aqueous solution of cationic surfactant cetyltrimethylammonium bromide (CTAB) was used to obtain a homeotropically aligned 5CB monolayer at the LC-aqueous interface resulting in a uniformly dark appearance. A highly specific amoxycillin aptamer (AMXA) was immobilised on the glass substrate as a target recognition probe for AMOX molecules. The specific binding of AMXA and AMOX molecules induces orientational changes in LC ordering resulting in a change in LC optical textures observed under a Polarized Optical Microscope (POM). A low limit of detection (LOD) of 10 nM for AMOX was obtained using this sensing system. Additionally, a high specificity for AMOX was also observed during comparative analysis. Finally, the developed biosensor was used to successfully detect AMOX in environments of potential application like tap water and lake water samples. Thus, the developed LC-based aptasensor can be a simple, sensitive and label‐free platform for monitoring real‐time levels of AMOX in freshwater environments. [ABSTRACT FROM AUTHOR]

We study the effects of concentration and size of the doped silver nanoparticles on material properties of 6CB nematic: 4-hexyl-4'-cyanobiphenyl using electrical, dielectric measurements along with the polarising microscopy methods. We show that the dispersed NPs do not affect the nematic-isotropic liquid transition temperature. We report that the doped NPs decrease the dielectric anisotropy, elasticity and viscosity of the material. We attribute this behaviour to the fact that the dispersed NPs lower the orientational order parameter of the nematic. However, the threshold voltage stays almost unaffected by the doped NPs and the switching-off time is decreased only at certain NPs concentration. Using our measured data, we test the validity of the predicted by the classical Maier-Saupe theory, linear dependence of the elasticity vs the square root of the order parameter. We show that while for the pure sample the mentioned dependence follows the classical prediction, the dispersed samples elasticity shows anomalous behaviour. We report that the mentioned dependence predicted by Gelbart-Ben Shaul theory fits well with the doped samples measured data. [ABSTRACT FROM AUTHOR]

The discovery of the cyanobiphenyl and related compounds in 1973 not only played a significant role in important innovations in displays and related technologies but also opened opportunities for testing of novel insights in understanding phase transitions and critical phenomena. In the study of these phenomena, high-resolution calorimetry made substantial contributions. In this paper, we present an overview of the high-resolution calorimetry results obtained during the past 50 years on the phase transitions that occur in the cyanobiphenyl compounds. For the isotropic–nematic and isotropic–smectic A transitions, their (weakly) first-order nature is well established and the temperature dependence of the pretransitional-specific heat capacity strongly points in the direction of a nearby tricritical point. For the nematic-smectic A transition, precise latent heat values of several binary liquid crystal (mainly of cyanobiphenyl type) mixtures give significant evidence on the Halperin, Lubensky and Ma prediction of the always weakly first-order nature of this transition. The dependence of the specific heat capacity critical exponent α on the width of the nematic range, resulting from coupling between the nematic and the smectic order parameters as pointed out by de Gennes, is well confirmed. [ABSTRACT FROM AUTHOR]

Calamitic molecules consisting of pentabromophenol tethered to cyanobiphenyl via a flexible alkyl chain were synthesised and characterised for their mesomorphic properties. New chemical structures differing in the length of the spacer (6a–f) were confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopies, and by elemental analysis. Compounds having six, eight, nine and ten methylene units in the spacer show room-temperature nematic liquid crystalline phases and the other derivatives are soft solids. The mesomorphic behaviour and thermal stability of all compounds have been investigated by polarised optical microscopy, differential scanning calorimetry and thermal gravimetric analysis, respectively. [ABSTRACT FROM AUTHOR]

We review recent research in various types of optical quantum computing using liquid crystal devices. First, we have investigated Young's Interference experiment using self-aligned liquid crystal (LC) devices and a logical "NOT" operation is achieved. Second, numerical quantization of interfering small photons using an LC retarder is investigated. Third, a Mach–Zehnder interferometer with an optical phase control by a twisted nematic (TN) LC device was studied. Fourth, a basic experiment on 2-bit quantum calculations related to the Deutsch-Jozsa algorithm on a linear optical quantum computer using the LC device as a linear optical element was investigated. [ABSTRACT FROM AUTHOR]

Liquid Crystal Elastomers (LCEs) are renowned for their reversible deformation capabilities. Yet, enhancing their mechanical strength while retaining such flexibility has posed a considerable challenge. To overcome this, we utilized 4D printing to develop an innovative composite of LCE with carbon fiber fabric (LCEC). This approach has notably increased the tensile strength of LCE by eightfold, all the while maintaining its exceptional capacity for reversible deformation. By adjusting the alignment angle between carbon fiber and the LCE printing direction from 0° to 90°, the LCEC demonstrates an array of new deformation patterns, including bending, twisting, wrapping, and S-shaped transformations, which are distinct from pure LCE materials. Our study unveils that LCE composites exhibit deformation processes markedly different from their pure material counterparts, with the ability of pure LCE to sustain tensile strains exceeding 1900%. These findings, previously undocumented and unexplored, represent a substantial contribution to the field of smart materials. Employing finite element analysis, we explored the carbon fiber and LCE matrix dynamics, revealing bending mechanics in LCECs. This combined experimental and simulation approach yields crucial insights for crafting durable, high-strength LCECs with diverse deformational properties, advancing smart material technology. [ABSTRACT FROM AUTHOR]

Due to the ability to switch between transparent and light scattering states, polymer dispersed liquid crystals (PDLC) and polymer stabilised cholesteric liquid crystals (PSCLC) are widely used in smart windows and flexible displays. A novel double-layer optical switch fabricated from a PDLC-PVA-PSCLC structure has been developed in this study, and the optimal formulation of each layer of the structure was investigated. In addition, the effect of adding (spin-coating) nanoparticles on overall switch performance was investigated. The double-layer switch under optimal conditions achieved 89.1% UV shielding, which also possessed excellent layer-by-layer driving performance and was able to modulate the UV shielding rate according to the voltage, with a tunable range of 74.83%-94.33%. Consequently, this optical device holds great promise for significant improvement and application in smart windows and flexible displays. [ABSTRACT FROM AUTHOR]

This research delves into the synthesis and characterisation of novel liquid crystal compounds derived from benzo[b]thiophene cores, focusing on their potential applications in microwave technology. Two synthetic strategies were developed to construct rigid cores, resulting in the successful synthesis of 10 compounds with varied terminal groups and lateral substituents. Correlations between molecular structure and mesomorphic properties were elucidated through extensive comparative analysis. Birefringence measurements and quantum chemical calculations further provided insights into the optical properties and polarisability anisotropy of the synthesised compounds. The results highlight the influence of structural diversity on the compounds' suitability for microwave applications. Specifically, compounds featuring carbon–carbon triple bonds and polar terminal groups demonstrated enhanced birefringence and polarisability values, indicating their potential in microwave device fabrication. This study underscores the importance of molecular design in optimising liquid crystal materials for advanced technological applications. [ABSTRACT FROM AUTHOR]

In the present investigation, two series of biphenyl embedded Schiff base-bis esters alkyl-(E)-4-(((4'-(decyloxy)-[1,1'-biphenyl]-4-yl)methylene)amino)-benzoate, BPK-(2–18) and alkyl-(E)-4-(((4'-((4-(decyloxy)benzoyl)oxy)-[1,1'-biphenyl]-4-yl)-methylene)amino)benzoate, BPEK-(8–18) containing either terminal alkoxy biphenyl core or central biphenyl core have been synthesised and studied for their self-assembling behaviour. The compounds of both series demonstrated enantiotropic liquid crystal properties, displaying typical calamitic mesophases (Smectic A (SmA), Smectic C (SmC)) across a broad temperature range and with high thermal stability. The bimorphic behaviour of new molecules has been investigated by VT-XRD analysis. The density function theory has been done to illustrate the experimental results of the mesomorphic properties of the studied compounds. Several parameters have been calculated such as molecular geometry, dipole moment, polarisability, aspect ratio, etc. The results showed that more planar compounds will attain more packed structures leading to the formation of more ordered smectic phases. [ABSTRACT FROM AUTHOR]

This study investigates the self-assembly and phase transitions of cholesteric liquid crystals (CLCs) when confined in nanotubes, specifically focusing on the variations in their molecular structures. A dissipative particle dynamics method was used to investigate how the changes in helix radius (${r_{{\rm{LC}}}}$ r LC ) and pitch ($P$ P) affect the behaviour of the LCs. For pitches of 24, 12, and 6, the orientation order parameter (${P_2}$ P 2 ) showed distinct trends during cooling. Smaller helix radii resulted in isotropic to nematic to smectic phase transitions, whereas larger radii resulted in a novel smectic phase with spiral structures (Sm $_{\rm{s}}$ s ). Circumferential local-order parameters (${P_{2r}}$ P 2 r and ${P_{2z}}$ P 2 z ) were introduced to better characterise the phases, and a disordered spiral-structure phase (Sm $_{{\rm{s}}2}$ s 2 ) with local perturbations was observed. The transitions between isotropic, nematic, and smectic phases, highlighting the influence of the pitch and helix radius, were observed from the phase diagrams. Smaller pitches and radii prevented the formation of stable structures; however, specific combinations induced characteristic spiral structures in the smectic phase. These results provide new insights into the self-assembly of confined CLCs, which have potential applications in the design of photonic devices and LC-based sensors. This study advances our understanding of phase control in quasi-one-dimensional systems and highlights the importance of molecular variations in liquid crystal behaviour. [ABSTRACT FROM AUTHOR]

Dye-doped cholesteric liquid crystals (DDCLCs) with a homeotropic initial state are more practical due to their lower power consumption and higher security. However, achieving the homeotropic initial state necessitates the use of long-pitch DDCLCs. The conventional formula for determining the planar (P) state transmittance of DDCLCs is inadequate for calculating the P state transmittance of long-pitch DDCLCs with pronounced optical activity. Therefore, in the experimental calculations and fitting, optical activity was introduced to amend the conventional formula and expand the calculation range to include visible wavelengths (400 nm-800 nm). Following numerous validations, a modified formula for calculating the P-state transmittance of DDCLCs was derived, which yields results closer to the actual values when optical activity is significant. This modification is of great significance in the design of long-pitch DDCLCs. [ABSTRACT FROM AUTHOR]

In this work, electromagnetic propagating modes within a planar waveguide featuring a cholesteric elastomer core whose helical axis is oriented perpendicular to the planar boundaries are analysed. The Maxwell equations and the constitutive equation are used to establish a novel configuration, enabling the tuning of mechanical stress through elastic strain in the perpendicular stretching along the helix axis. The derived set of equations is numerically solved, presuming the waveguide to be surrounded by either air or a vacuum medium. The corresponding band structure and the ratio between electric and magnetic modes have been plotted as a function of angular frequency. The amplitudes of the electromagnetic field profiles are also investigated as functions of position. The ratio of Transverse Electric and Transverse Magnetic modes, along with the cut-off frequencies, is also examined as functions of strain. Finally, the mixing of transverse electric and magnetic modes to generate new eigenmodes, as well as the investigation of their propagation conditions within the waveguide, is examined in this study. [ABSTRACT FROM AUTHOR]

Most of the current highly polar rod-shaped molecules that form ferroelectric nematic (NF) phase do so only at elevated temperatures and multicomponent mixtures are generally needed to obtain a broad and room temperature range NF phase. In this work, we describe the synthesis, phase characterisation and measurement of various physical properties of a new ferroelectric nematic compound 4-[(4-nitrophenoxy)carbonyl]phenyl 2-isopropoxy-4-methoxybenzoate (RT11165). The molecular structure of RT11165 with a 2-isopropoxy group differs only by a substitution of the 2-methoxy group found in the prototype ferroelectric nematic material 4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (RM734). This small structure change produces a rather dramatic change in phase behaviour leading to an NF phase from 63°C down to room temperature. Below about 45°C the rotational viscosity of RT11165 increases critically and the temperature dependence indicates a glass transition at ~19°C. The transparent and polar glassy state of RT11165, which should be also piezoelectric, is a good candidate for energy storage, piezoecatalysis, data storage and other applications. [ABSTRACT FROM AUTHOR]

This article is based on the Density Functional Theory (DFT) simulations approach to examine the structural and vibrational behaviour of pure 6O.6 and fluorinated 6O.6 liquid crystalline compounds. The molecular interactions of the molecules were investigated by their optimised molecular structure. Identification of significant functional groups and their dynamic behaviours are made with the help of vibrational frequencies obtained through DFT calculations. Vibrational Energy Distribution Analysis (VEDA) software was used to perform the Potential Energy Distribution (PED) function of FT-IR and Raman spectra. Furthermore, changes in vibrational peaks provide insight into structural modifications. This investigation mainly focused on analysing the different reactivity, thermodynamic parameters and non-linear optical (NLO) properties of the compounds. This also helps to open a new path for further investigations into optoelectronic applications and molecular dynamics. [ABSTRACT FROM AUTHOR]

In this study, polymer-stabilised cholesterol-based liquid crystal (PSLC) broadband reflective films were prepared by doping UV absorbers and chiral compounds in bilayer poly (methyl methacrylate) (PMMA) nanofiber films. Broadband reflection was achieved by diffusion of the UV absorber and chiral compounds in the bilayer nanofibers into the liquid crystal layer, which resulted in the formation of an inhomogeneous pitch distribution in the liquid crystal layer. To attain an optimal reflective effect, various factors such as polymer monomer concentration, concentration of chiral compounds in the spun film, diffusion temperature, diffusion time, and intensity of polymerised light were investigated. The effects of these factors on the reflective bandwidth were explored. The method significantly broadened the reflective bandwidth of the cholesteric phase liquid crystal layer, establishing the foundation for studying the combination of nanofiber films with cholesteric phase liquid crystals to form an adjustable pitch. [ABSTRACT FROM AUTHOR]