Order-disorder behavior in the ferroelectric nematic phase investigated via Raman spectroscopy.

Polar-ordered fluids are of interest both fundamentally and from an application standpoint. The recently discovered ferroelectric nematic phase is an example of a polar-ordered fluid, and while there has been extensive research interest in these materials, some of the fundamental properties are yet to be fully understood. Here, we report the order parameters of one of the first known materials that exhibit a ferroelectric nematic phase, RM734, determined via Raman spectroscopy.

Structure-Property Relationships in Auxetic Liquid Crystal Elastomers-The Effect of Spacer Length.

Auxetics are materials displaying a negative Poisson's ratio, i.e., getting thicker in one or both transverse axes when subject to strain.

Spontaneous symmetry breaking in polar fluids.

Spontaneous symmetry breaking and emergent polar order are each of fundamental importance to a range of scientific disciplines, as well as generating rich phase behaviour in liquid crystals (LCs). Here, we show the union of these phenomena to lead to two previously undiscovered polar liquid states of matter. Both phases have a lamellar structure with an inherent polar ordering of their constituent molecules.

Toward Monodomain Nematic Liquid Crystal Elastomers of Arbitrary Thickness through PET-RAFT Polymerization.

Liquid crystal elastomers (LCEs) are polymeric materials that are proposed for a range of applications. However, to reach their full potential, it is desirable to have as much flexibility as possible in terms of the sample dimensions, while maintaining well-defined alignment. In this work, photoinduced electron/energy transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization is applied to the synthesis of LCEs for the first time.

Controlling the Optical Properties of Transparent Auxetic Liquid Crystal Elastomers.

Determining the tunability of the optical coefficients, order parameter, and transition temperatures in optically transparent auxetic liquid crystal elastomers (LCEs) is vital for applications, including impact-resistant glass laminates. Here, we report measurements of the refractive indices, order parameters, and transition temperatures in a family of acrylate-based LCEs in which the mesogenic content varies from ∼50 to ∼85%. Modifications in the precursor mixture allow the order parameter, ⟨⟩, of the LCE to be adjusted from 0.

A wireless fluorescent flexible force sensor based on aggregation-induced emission doped liquid crystal elastomers.

Flexible strain sensors have drawn a lot of interest in various applications including human mobility tracking, rehabilitation/personalized health monitoring, and human-machine interaction, but suffer from interference of electromagnetic (EM). To overcome the EM interference, flexible force sensors without sensitive electronic elements have been developed, with drawbacks of bulky modules that hinders their applications in remote measurement with power-free environment. Therefore, it is highly desirable to fabricate a compact wireless flexible force sensor but it is still a challenge.

Room-temperature ferroelectric nematic liquid crystal showing a large and diverging density.

The ferroelectric nematic phase (N) is a recently discovered phase of matter in which the orientational order of the conventional nematic liquid crystal state is augmented with polar order. Atomistic simulations suggest that the polar N phase would be denser than conventional nematics owing to contributions from polar order. Using an oscillating U-tube densitometer, we obtain detailed temperature-dependent density values for a selection of conventional liquid crystals with excellent agreement with earlier reports.

Ultra-stable liquid crystal droplets coated by sustainable plant-based materials for optical sensing of chemical and biological analytes.

Herein, we demonstrate for the first time the synthesis of ultra-stable, spherical, nematic liquid crystal (LC) droplets of narrow size polydispersity coated by sustainable, biodegradable, plant-based materials that trigger a typical bipolar-to-radial configurational transition in dynamic response to chemical and biological analytes. Specifically, a highly soluble polymer, potato protein (PoP) and a physically-crosslinked potato protein microgel (PoPM) of ∼100 nm in diameter, prepared from the PoP, a byproduct of the starch industry, were compared for their ability to coat LC droplets. Although both PoP and PoPM were capable of reducing the interfacial tension between water and -tetradecane <30 mN m, PoPM-coated LC droplets showed better stability than the PoP-coated droplets a Pickering-like mechanism.

Chiral nematic liquid crystal droplets as a basis for sensor systems.

For a series of phospholipid coated calamitic nematic liquid crystal droplets (5CB, 6CB, 7CB, E7 and MLC7023) of diameter ∼18 μm, the addition of chiral dopant leaves the sign of surface anchoring unchanged. Herein we report that for these chiral nematic droplets an analyte induced transition from a Frank-Pryce structure (with planar anchoring) to a nested-cup structure (with perpendicular anchoring) is accompanied by changes in the intensity of reflected light. We propose this system as both a general scheme for understanding director fields in chiral nematic liquid crystal droplets with perpendicular anchoring and as an ideal candidate to be utilised as the basis for developing cheap, single use LC-based sensor devices.

Light-Driven Dynamic Hierarchical Architecture of Three-Dimensional Self-Assembled Cholesteric Liquid Crystal Droplets.

Cholesteric liquid crystals have attracted much attention in biosensors, in communication systems, security identification, hierarchical materials assembly, and microlasers, due to their complex and interesting structures accompanied by particular optical properties making them low-cost, label-free and sensitive. However, the reports of CLC droplets with stable topological configurations are still very limited, which hinders the fast development and broad application of CLC droplet-based devices. In this paper, we manifest light-driven changes in the topological configuration of cholesteric liquid crystals droplets, examined experimentally.

Direct Observation of Biaxial Nematic Order in Auxetic Liquid Crystal Elastomers.

Auxetic materials exhibit a negative Poisson's ratio, i.e., they become thicker rather than thinner in at least one dimension when strained.

The risk matrix: Drug-related deaths in prisons in England and Wales, 2015-2020.

This article explores the factors contributing to drug-related deaths in English and Welsh prisons between 2015 and 2020. Based on content analysis of all Prison and Probation Ombudsman 'other non-natural' fatal incident investigation reports, descriptive statistics were generated. Qualitative analysis explored the circumstances surrounding deaths and key risk factors.

A mathematical model for the auxetic response of liquid crystal elastomers.

We develop a mathematical model that builds on the surprising nonlinear mechanical response observed in recent experiments on nematic liquid crystal elastomers. Namely, under uniaxial tensile loads, the material, rather than thinning in the perpendicular directions, becomes thicker in one direction for a sufficiently large strain, while its volume remains unchanged. Motivated by this unusual large-strain auxetic behaviour, we model the material using an Ogden-type strain-energy function and calibrate its parameters to available datasets.

Influence of Liquid Crystallinity and Mechanical Deformation on the Molecular Relaxations of an Auxetic Liquid Crystal Elastomer.

Liquid Crystal Elastomers (LCEs) combine the anisotropic ordering of liquid crystals with the elastic properties of elastomers, providing unique physical properties, such as stimuli responsiveness and a recently discovered molecular auxetic response. Here, we determine how the molecular relaxation dynamics in an acrylate LCE are affected by its phase using broadband dielectric relaxation spectroscopy, calorimetry and rheology. Our LCE is an excellent model system since it exhibits a molecular auxetic response in its nematic state, and chemically identical nematic or isotropic samples can be prepared by cross-linking.

A Fluorescence Sensor for Pb Detection Based on Liquid Crystals and Aggregation-Induced Emission Luminogens.

Heavy metals, such as lead ions, are regarded as the main environmental contaminants and have a negative impact on human bodies, making detection technologies of lead ions critical. However, most existing detection methods suffer from time consumption, complicated sample pretreatment, and expensive equipment, which hinder their broad use in real-time detection. Herein, we show a new fluorescence sensor for detecting lead ions derived from liquid crystals doped with an aggregation-induced emission luminogen.

Liquid Crystal Elastomers for Biological Applications.

The term liquid crystal elastomer (LCE) describes a class of materials that combine the elastic entropy behaviour associated with conventional elastomers with the stimuli responsive properties of anisotropic liquid crystals. LCEs consequently exhibit attributes of both elastomers and liquid crystals, but additionally have unique properties not found in either. Recent developments in LCE synthesis, as well as the understanding of the behaviour of liquid crystal elastomers-namely their mechanical, optical and responsive properties-is of significant relevance to biology and biomedicine.

Production of giant unilamellar vesicles and encapsulation of lyotropic nematic liquid crystals.

We describe a modified microfluidic method for making Giant Unilamellar Vesicles (GUVs) via water/octanol-lipid/water double emulsion droplets. At a high enough lipid concentration we show that the de-wetting of the octanol from these droplets occurs spontaneously (off-chip) without the need to use shear to aid the de-wetting process. The resultant mixture of octanol droplets and GUVs can be separated by making use of the buoyancy of the octanol.

Exploring gendered differences among polish migrants in the UK in problematic drinking and pathways into and through alcohol treatment.

Few studies have focused on the gendered differences amongst Polish migrants in their use of alcohol or access to treatment services. This study explored the divergent pathways through alcohol use, misuse and treatment access in a group of Polish migrants in London. Using an intersectionality framework we examine the ways that social attitudes toward gender in both communities and access to services related to migrant status and class are experienced.

Protein Microgel-Stabilized Pickering Liquid Crystal Emulsions Undergo Analyte-Triggered Configurational Transition.

Herein, we report a novel approach that involves Pickering stabilization of micometer-sized liquid crystal (LC) droplets with biocompatible soft materials such as a whey protein microgel (WPM) to facilitate the analysis of analyte-induced configurational transition of the LC droplets. The WPM particles were able to irreversibly adsorb at the LC-water interface, and the resulting WPM-stabilized LC droplets possessed a remarkable stability against coalescence over time. Although the LC droplets were successfully protected by a continuous network of the WPM layer, the LC-water interface was still accessible for small molecules such as sodium dodecyl sulfate (SDS) that could diffuse through the meshes of the adsorbed WPM network or through the interfacial pores and induce an LC response.

Textile materials inspired by structural colour in nature.

The concept of mimicking structural colour in nature as an alternative to traditional textile coloration techniques would reduce dependency on dyes, pigments and vast quantities of water in the textile supply chain. Structural colours originate from the physical interaction of light with nanoscale structures. This is exhibited in the bodies and wings of certain species of butterfly, beetles and plants.

Control of Director Fields in Phospholipid-Coated Liquid Crystal Droplets.

In liquid crystal (LC) droplets, small changes in surface anchoring energy can produce large changes in the director field which result in readily detectable optical effects. This makes them attractive for use as biosensors. Coating LC droplets with a phospholipid monolayer provides a bridge between the hydrophobic world of LCs and the water-based world of biology and makes it possible to incorporate naturally occurring biosensor systems.

Efficiency improvements in a dichroic dye-doped liquid crystal Fresnel lens.

A dichroic dye-doped liquid crystal Fresnel lens was fabricated and investigated to observe the combination of phase and amplitude modulation based focusing. An anthraquinone dichroic dye was doped into a liquid crystal host, which when in the Fresnel lens configuration, generates a Fresnel zone plate with alternating "transparent" and "opaque" zones. The zones were induced by using photo-alignment of a light-sensitive alignment layer to generate the alternating pattern.

Lipid coated liquid crystal droplets for the on-chip detection of antimicrobial peptides.

We describe a novel biosensor based on phospholipid-coated nematic liquid crystal (LC) droplets and demonstrate the detection of Smp43, a model antimicrobial peptide (AMP) from the venom of North African scorpion Scorpio maurus palmatus. Mono-disperse lipid-coated LC droplets of diameter 16.7 ± 0.