Electric field-induced splay of molecular orientation, called the Fréedericksz transition, is a fundamental electro-optic phenomenon in nonpolar nematic liquid crystals. In ferroelectric NF with spontaneous electric polarization P , suppressed since it produces bound charges. Here, we demonstrate that an alternating current (ac) field causes three patterns polarization. At low voltages, oscillates around field-free orientation no stationary deformations. As voltage increases, acquires...

We describe the experimental observation of a crystal structure formed by glycerol droplets suspended in nematic liquid crystal. The exhibits high density hexagonal ordering. have experimentally observed noticeable interaction between with tangential boundary conditions. Within scope known models we discuss nature appropriate mechanisms interaction.

We report on the optical properties of nematic (N) phase formed by lyotropic chromonic liquid crystals (LCLCs) in well aligned planar samples. LCLCs belong to a broad class materials one-dimensional molecular self-assembly and are similar other systems such as "living polymers" "wormlike micelles." study three water soluble LCLC forming materials: disodium chromoglycate, derivative indanthrone called Blue 27, perylene Violet 20. The individual molecules have planklike shape assemble into...

Using a magnetic Frederiks transition technique, we measure the temperature and concentration dependences of splay K1, twist K2, bend K3 elastic constants for lyotropic chromonic liquid crystal sunset yellow formed through noncovalent reversible aggregation organic molecules in water. K1 are comparable to each other an order magnitude higher than K2. At concentrations lower temperatures, ratios K1/K3 K1/K2 increase, which is attributed elongation self-assembled aggregates, feature not found...

In the simplest realization of Brownian motion, a colloidal sphere moves randomly in an isotropic fluid; its mean squared displacement (MSD) grows linearly with time $\textitτ$. motion orientationally ordered fluid, nematic, is anisotropic, MSD being larger along axis molecular orientation, called director. We show that at short scales, anisotropic diffusion nematic becomes also anomalous, growing slower (subdiffusion) and faster (superdiffusion) than The anomalous occurs scales correspond...

Understanding nanoscale mechanisms responsible for the recently discovered ferroelectric nematics can be helped by direct visualization of self-assembly strongly polar molecules. Here, we report on scanning tunneling microscopy studies monomolecular layers a nematic liquid crystal reconstructed Au(111) surface. The monolayers are obtained deposition from solution at ambient conditions. adsorbed molecules self-assemble into regular rows with tilted orientation, resembling layered structure...

We demonstrate a variety of ordered patterns, including hexagonal structures and chains, formed by colloidal particles (droplets) at the free surface nematic liquid crystal (LC). The placement introduces new type particle interaction as compared to entirely in LC bulk. Namely, director deformations caused lead distortions interface thus capillary attraction. elastic-capillary coupling is strong enough remain relevant even micron scale when its buoyancy-capillary counterpart becomes irrelevant.

In this Letter, we demonstrate that the symmetry of elastic interaction between dipolar and quadrupolar colloidal particles in nematic liquid crystal leads to a novel variety 2D "binary" crystals, which have not been observed any system. The dipolar-quadrupolar is highly anisotropic shows power-law dependence when approach each other along director field with pair-binding energy order several thousands k(B)T for 4 microm diameter colloids.

We show that, contrary to intuition, small (< or =1 microm) transparent particles can be trapped and manipulated in a nematic liquid crystal using an intense laser beam, although their index of refraction is lower than both refractive indices the surrounding birefringent fluid. Two mechanisms are identified that responsible for this anomalous trapping: (i) surface-induced distortion media around particle, creating high-index "cloud" colloid, (ii) laser-induced (partial) melting nematic,...

Glycerol droplets at a nematic-liquid-crystal-air interface form two different lattices--hexagonal and dense quasihexagonal--which are separated by the energy barrier can coexist. Director distortions around each droplet an elastic dipole. The first order transition between lattices is driven reduction of dipole-dipole repulsion through reorientation these dipoles. elastic-capillary attraction essential for both lattices. effect has many-body origin.

The surface alignment of lyotropic chromonic liquid crystals can not only be planar (tangential) but also homeotropic, with self-assembled aggregates perpendicular to the substrate, as demonstrated by mapping optical retardation and three-dimensional imaging director field. With time, homeotropic nematic undergoes a transition into tangential state. anchoring is discontinuous described double-well potential two minima corresponding orientation.

In this paper, we examine directed self-assembly in a 2D binary system of dipolar and quadrupolar colloidal particles with normal surface boundary conditions, dispersed the nematic liquid crystal. Using laser tweezers, assembled large variety stable crystal structures. all analyzed structures, particles, their treatment cell conditions were same, which gives us ability to systematically follow evolution assembly when many are present. We present an analogy between molecular organization...

A temperature-driven anchoring transition strongly influenced by ionic impurities appears in a nematic liquid crystal composed of centrosymmetric molecules. Two parameters, the tilt angle and strength, were measured. The observed phenomena are explained as result balance between orienting tendencies electric double layers direct molecular interactions at interface.

We describe and analyze laser trapping of small colloidal particles in a nematic liquid crystal, where the index refraction colloids is smaller compared to indices crystal. Two mechanisms are identified that responsible for this anomalous trapping: (i) below optical Fr\'eedericksz transition, due anisotropic dielectric interaction polarized light with inhomogeneous director field around colloid, (ii) above accompanied by elasticity-mediated between optically distorted region crystal colloid....

Spherical colloidal particles with normal and tangential surface director alignment in a nematic liquid crystal induce elastic quadrupoles of opposite signs that attract one another along perpendicular to the director. We utilize this unique angular profile mixed quadrupolar interaction build 2D crystals square lattices by laser tweezers.

We propose lyotropic chromonic liquid crystals (LCLCs) as a distinct class of materials for organic electronics. In water, the molecules stack on top each other into elongated aggregates that form orientationally ordered phases. The aligned aggregated structure is preserved when material deposited onto substrate and dried. dried LCLC films show strongly anisotropic electric conductivity semiconductor type. field-effect carrier mobility measured along molecular in unoptimized V20 0.03 cm^2...

In this work, we describe the design and synthesis of novel core-fluorinated Schiff base monomers conjugated polymers based on them. The new fully aromatic highly fluorinated poly(azomethine ether)s (PAMEs) were prepared by polycondensation azomethine-containing compounds. structure confirmed FTIR, 1H, 13C, 19F NMR spectroscopic analysis. influence condition properties PAME compounds was investigated. Application polarization microscopy with a temperature control thermal stage revealed...

Polymer multicomponent materials containing conjugated fragments (such as azo- or azomethine groups) have attracted significant attention due to their possible use in the efficient reversible stimuli-responsive, light-responsive devices. Light-responsive polyazomethines with azo groups backbone (Azo-Pams) are synthesized by polycondensation of tetrafluorobenzene- octafluorobiphenylene-based bis-hydroxybenzaldehydes hexamethylenediamine. The polymers feature simultaneous combination and...

In this paper, we give an overview of novel main-chain azobenzene-based fluorinated poly(arylene ether)s with different content azo groups, aiming at providing a better understanding the link between number N═N bonds and macroscopic response material. We discuss chemical synthesis molecular structure report on comprehensive analysis polymer properties, thermal behavior, mechanical strength. show that higher azobenzene moieties reduces strength materials. On other hand, polymers demonstrate...

The domain structure of a fluid ferroelectric nematic is dramatically different from the solid ferroelectrics since it not restricted by rectilinear crystallographic axes and planar surface facets. We demonstrate that thin films seeded colloidal inclusions produce walls (DWs) in shape conics such as parabola. These reduce bound charge within domains at DWs. An adequate description structures requires one to analyze electrostatic energy, which challenging task. Instead, we good approximation...

The existence of polar electro-optic effect induced by a surface polarization nematic liquid crystal is proved using simultaneous action vertical dc and high-frequency ac electric fields on the homeotropically aligned with positive dielectric anisotropy. proposed method enables us to measure anchoring energy in course same experiment. evaluated for pentylcyanobiphenyl--silicone elastomere interface 1 order magnitude larger than flexoelectric constant.

We study the anchoring mechanism due to substrate-adsorbed ions by examining a related transition. An analytical solution Poisson equation shows that, as their number suffices for non-negligible contribution, surface field is screened over some characteristic microscopic distance. It shown both theoretically and experimentally that critical temperature of transition can be controlled bulk ion density through its relation adsorbed ions.

We characterized the optical properties of a photoresist-based micro-lens using stressed liquid crystal matrix for high-speed variation focal distance. also determined operational parameters adaptive spherical and cylindrical arrays. The resulting elements feature fast response times, around 1 ms, with length range 2600-970 μm.