Chiral nematic droplets with parallel surface anchoring

Xu, F.; Crooker, P. P.

doi:10.1103/physreve.56.6853

Cited by 121 publications

(126 citation statements)

References 14 publications

Supporting

Mentioning

115

Contrasting

Unclassified

Order By: Relevance

“…1F shows the Jones matrix simulation of the optical pattern of a twisted bipolar configuration that exhibits, among other features, a disconnected bright ellipse similar to that observed in Fig. 1D and in thermotropic chiral nematic droplets (34).…”

Section: Resultssupporting

confidence: 53%

Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy

Jeong

Davidson

Collings

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

126

133

View full text Add to dashboard Cite

Confined liquid crystals (LC) provide a unique platform for technological applications and for the study of LC properties, such as bulk elasticity, surface anchoring, and topological defects. In this work, lyotropic chromonic liquid crystals (LCLCs) are confined in spherical droplets, and their director configurations are investigated as a function of mesogen concentration using bright-field and polarized optical microscopy. Because of the unusually small twist elastic modulus of the nematic phase of LCLCs, droplets of this phase exhibit a twisted bipolar configuration with remarkably large chiral symmetry breaking. Further, the hexagonal ordering of columns and the resultant strong suppression of twist and splay but not bend deformation in the columnar phase, cause droplets of this phase to adopt a concentric director configuration around a central bend disclination line and, at sufficiently high mesogen concentration, to exhibit surface faceting. Observations of director configurations are consistent with Jones matrix calculations and are understood theoretically to be a result of the giant elastic anisotropy of LCLCs.emulsions | complex colloids T he director configurations of confined liquid crystals exhibit a rich phenomenology, the physics of which is determined by a delicate interplay of topology, elastic free energy, and anchoring conditions at the boundaries (1-12). Droplets present arguably the simplest and most symmetric confining container for liquid crystals. Droplets of thermotropic liquid crystals (TLCs) and the manipulation of their director configurations, for example, are actively studied, in part because of their demonstrated use as core materials in display technologies (3, 13) and their potential applications ranging from biosensors (14, 15) to microlasers (16). Indeed, significant fundamental and technological progress has been made with TLC droplets, because their bulk elasticity and surface anchoring phenomena are now well understood and easily controlled.Lyotropic chromonic liquid crystals (LCLCs) are composed of organic, charged, and plank-like mesogens that self-assemble in water into columnar aggregates via noncovalent electrostatic, excluded volume, hydrophobic, and pi-pi stacking interactions (17)(18)(19)(20). The aggregates, in turn, assemble into nematic or columnar phases, depending on temperature and concentration. A variety of organic molecules such as dyes, drugs, and biomolecules form LCLCs (17-28). However, far less is known about the fundamental science and applications potential of LCLCs than the more-studied TLCs. Indeed, basic properties of LCLCs, including aggregate size distribution and formation dynamics, bulk elasticity, and surface anchoring are neither fully characterized nor understood and are the subject of exciting ongoing research. Only recently, for example, have measurements been made of fundamental properties, such as the FrankOseen elastic constants (28, 29), of any LCLC, and they have revealed unusual concentration and temperature dependences of the splay ...

show abstract

Section: Resultssupporting

confidence: 53%

Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy

Jeong

Davidson

Collings

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

126

133

View full text Add to dashboard Cite

show abstract

“…A characteristic radial defect [7,8] is observed in the former case, see white arrow in Fig. 3(b), whereas the unchanged dark cross pattern indicates radially symmetric optical anisotropy in the latter case [8].…”

mentioning

confidence: 98%

“…2(a), we measure the intrinsic Bragg angle B ¼ 25:1 at 0 ¼ 532 nm. This is verified in situ for cholesteric droplets dispersed in glycerol, which ensures parallel anchoring of the director at cholesteric-glycerol interface, hence, a radial distribution of the helical axis for p ( R where R is the droplet radius [7,8]. For this purpose, we measure the radius R B of the total reflection cross-section area under B -polarized light at 0 ¼ 532 nm, as a function of R, see Fig.…”

mentioning

confidence: 99%

Spin Controlled Optical Radiation Pressure

Tkachenko

Brasselet

2013

Phys. Rev. Lett.

View full text Add to dashboard Cite

International audienceWe report on the full control of the optical radiation pressure at fixed photon flux and incident angle by the photon spin. This is done by using transparent chiral liquid crystal droplets that enable a strong coupling between the linear and angular degrees of freedom of a light field. From these results, we anticipate optical sorting of particles with different chirality as well as novel optical trapping and micromanipulation strategies

show abstract

“…The tendency to create layer-like helical structure competes with the spherical boundary conditions of the droplet, creating a frustrated environment with a multitude of metastable states 21,[25][26][27] . Ensuing conformations not only depend on the anchoring, but vary continuously with the cholesteric pitch.…”

mentioning

confidence: 99%

Topological zoo of free-standing knots in confined chiral nematic fluids

2014

View full text Add to dashboard Cite

Knotted fields are an emerging research topic relevant to different areas of physics where topology plays a crucial role. Recent realization of knotted nematic disclinations stabilized by colloidal particles raised a challenge of free-standing knots. Here we demonstrate the creation of free-standing knotted and linked disclination loops in the cholesteric ordering fields, which are confined to spherical droplets with homeotropic surface anchoring. Our approach, using free energy minimization and topological theory, leads to the stabilization of knots via the interplay of the geometric frustration and intrinsic chirality. Selected configurations of the lowest complexity are characterized by knot or link types, disclination lengths and self-linking numbers. When cholesteric pitch becomes short on the confinement scale, the knotted structures change to practically unperturbed cholesteric structures with disclinations expelled close to the surface. The drops with knots could be controlled by optical beams and may be used for photonic elements.

show abstract

Chiral nematic droplets with parallel surface anchoring

Cited by 121 publications

References 14 publications

Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy

Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy

Spin Controlled Optical Radiation Pressure

Topological zoo of free-standing knots in confined chiral nematic fluids

Contact Info

Product

Resources

About