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Abstract The dynamics of swimming bacteria depend on the properties of their habitat media. Recently it is shown that the motion of swimming bacteria dispersed directly in a non‐toxic water‐based lyotropic chromonic liquid crystal can be controlled by the director field of the liquid crystal. Here, we investigate whether the macroscopic polar order of a ferroelectric nematic liquid crystal (N_F) can be recognized by bacteria B. Subtilis swimming in a water dispersion adjacent to a glassy N_Ffilm by surface interactions alone. Our results show that B. Subtilis tends to move in the direction antiparallel to the spontaneous electric polarization at the N_Fsurface. Their speed is found to be the same with or without a polar N_Flayer. In contrast to observation on crystal ferroelectric films, the bacteria do not get immobilized. These observations may offer a pathway to creation of polar microinserts to direct bacterial motion in vivo. 

A set of short-tailed discotic liquid crystals are presented which feature a mesophase despite having methoxy units as tails. Their unusual properties are a result of strategic fluorination, with more fluorination leading to broader mesophase ranges. 

Abstract Manipulating light is an important area of optical research and development. To that end, tunable dichroic devices in which the reflectivity at differing wavelengths can be adjusted, are particularly valuable. This work is motivated by recent studies of the optical properties of chiral ferroelectric nematic liquid crystals (FNLCs). Here electro‐optical studies are presented on two room temperature, FNLC materials that demonstrate electrically tunable reflectivity when subject to a field below 0.2 V µm⁻¹. Moreover, under appropriate conditions, the reflectivity can also be electrically (and reversibly) tuned (without change of color) from 0% to 40%. Reversible, low voltage tunable mirrors, having miniscule power consumption and operable around ambient temperature are expected to be useful in diverse applications ranging from energy‐saving, smart windows to virtual reality interfaces. 

We present discotic liquid crystals consisting of fluorinated triphenylene with unusually short tails, including mere methoxy or ethoxy tails. Understanding these short-tailed liquid crystals may lead to new applications for discotic liquid crystals. 

Abstract Microtubules and catalytic motor proteins underlie the microscale actuation of living materials, and they have been used in reconstituted systems to harness chemical energy to drive new states of organization of soft matter (e.g., liquid crystals (LCs)). Such materials, however, are fragile and challenging to translate to technological contexts. Rapid (sub‐second) and reversible changes in the orientations of LCs at room temperature using reactions between gaseous hydrogen and oxygen that are catalyzed by Pd/Au surfaces are reported. Surface chemical analysis and computational chemistry studies confirm that dissociative adsorption of H₂on the Pd/Au films reduces preadsorbed O and generates 1 ML of adsorbed H, driving nitrile‐containing LCs from a perpendicular to a planar orientation. Subsequent exposure to O₂leads to oxidation of the adsorbed H, reformation of adsorbed O on the Pd/Au surface, and a return of the LC to its initial orientation. The roles of surface composition and reaction kinetics in determining the LC dynamics are described along with a proof‐of‐concept demonstration of microactuation of beads. These results provide fresh ideas for utilizing chemical energy and catalysis to reversibly actuate functional LCs on the microscale. 

A dynamic light scattering study of director fluctuations in the antiferroelectric (AF) phase of the ferroelectric nematic liquid crystal DIO is reported. 

The isotropic to ferroelectric nematic liquid transition was theoretically studied over one hundred years ago, but its experimental studies are rare. Here we present experimental results and theoretical considerations of novel electromechanical effects of ferroelectric nematic liquid crystal droplets coexisting with the isotropic melt. We find that the droplets have flat pancake-like shapes that are thinner than the sample thickness as long as there is room to increase the lateral droplet size. In the center of the droplets a wing-shaped defect with low birefringence is present that moves perpendicular to a weak in-plane electric field, and then extends and splits in two at higher fields. Parallel to the defect motion and extension, the entire droplet drifts along the electric field with a speed that is independent of the size of the droplet and is proportional to the amplitude of the electric field. After the field is increased above 1 mV μm −1 the entire droplet gets deformed and oscillates with the field. These observations led us to determine the polarization field and revealed the presence of a pair of positive and negative bound electric charges due to divergences of polarization around the defect volume. 

Liquid crystal properties of compounds with a variety of polar terminal groups including cyano, fluoro, isothiocyanato, etc., were studied well, however, not enough attention was given to nitro terminal compounds. In this work, a series of fluorine tail terminated alkoxy nitrobiphenyl compounds were synthesised and their mesogenic properties were analysed. In addition, the simple alkoxy nitrobiphenyl compounds were synthesised and analysed in order to compare them with fluoro-alkoxy nitrobiphenyl compounds and for binary mixture analysis. Fluorine tail termination to the alkoxy chain does suppress the smectic phase that was observed for the simple alkoxy nitrobiphenyl compounds with longer chains. Fluorine tail terminated alkoxy nitrobiphenyl compounds with longer chains (C7-C10) show monotropic nematic phase around ambient temperature and supercooling properties and these compounds are useful for a binary mixture analysis. Moreover, computation and experimental analyses of the alkoxy nitrobiphenyl compounds were performed to investigate the potential use of these nitro terminal compounds as chemoresponsive liquid crystal materials. 

A new synthetic approach for fluorinated alkoxytriphenylene discotic liquid crystals is presented. This methodology exploits the previously described photocyclodehydrofluorination (PCDHF) reaction for the preparation of fluorinated triphenylene derivatives coupled with a variety of nucleophilic aromatic substitution (S N Ar) reactions. This particular combination of reactions provides a versatile route to discotic materials with carefully controlled core fluorine and alkoxy tail content. In the course of these studies, new discotic materials with minimal tail content have been revealed. The mesogenic properties of these materials are reported, and their charge transport properties are measured using the time of flight technique.