Parity breaking in nematic tactoids

Prinsen, Peter; Schoot, Paul van der

doi:10.1088/0953-8984/16/49/003

Cited by 44 publications

(91 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3A). Such a texture corresponds to the standard models of the axially symmetric bulk tactoids (26)(27)(28) in whichn joins the two cusps along the axis. Away from the axis,n is curved to satisfy the tangential boundary conditions.…”

Section: Resultsmentioning

confidence: 98%

“…The shape and internal structure of tactoids are controlled by the balance of anisotropic surface tension at the I-N interface and by internal orientational elasticity of the N domain, as discussed in recent publications (7,(24)(25)(26)(27)(28). For rod-like building units, such as TMV rods, the surface orientation is typically tangential, so thatn follows the meridional lines and connects two opposite poles of the spindle, thus establishing a bipolar tactoidal structure with splay (near the poles) and bend (near the equatorial plane) deformations ofn.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals

Tortora

Lavrentovich

2011

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

163

171

View full text Add to dashboard Cite

In many colloidal systems, an orientationally ordered nematic (N) phase emerges from the isotropic (I) melt in the form of spindle-like birefringent tactoids. In cases studied so far, the tactoids always reveal a mirror-symmetric nonchiral structure, sometimes even when the building units are chiral. We report on chiral symmetry breaking in the nematic tactoids formed in molecularly nonchiral polymer-crowded aqueous solutions of low-molecular weight disodium cromoglycate. The parity is broken by twisted packing of self-assembled molecular aggregates within the tactoids as manifested by the observed optical activity. Fluorescent confocal microscopy reveals that the chiral N tactoids are located at the boundaries of cells. We explain the chirality induction as a replacement of energetically costly splay packing of the aggregates within the curved bipolar tactoidal shape with twisted packing. The effect represents a simple pathway of macroscopic chirality induction in an organic system with no molecular chirality, as the only requirements are orientational order and curved shape of confinement.parity breaking | twisted tactoids | geometrical anchoring | nematic-isotropic coexistence I n 1949, Onsager demonstrated theoretically that a dispersion of long rigid rods develops an organized state, a so-called nematic (N) with rods being parallel to each, once their concentration exceeds some critical value (1). This remarkable collective behavior with an establishment of nonpolar axis of alignmentn ¼ −n, called the director, stems from the molecular symmetry alone, as the only requirement of the Onsager model is that the rods do not overlap. The theory was inspired by Bernal and Fankuchen's experiments (2) on aqueous suspensions of tobacco mosaic viruses (TMV) that phase separated into an isotropic (I) phase with a relatively low concentration of TMV rods and an N phase with a high concentration of TMV. The N domains emerged as spindle-like "tactoids" (3, 4) with the axes of rods following the meridians of the spindles. Besides TMV dispersions (2, 5), the N tactoids have been experimentally documented in water dispersions of many other materials, such as vanadium pentoxide (3, 4, 6, 7), bohemite rods (8), fd viruses (9, 10), f-actin (11), carbon nanotubes (12), as well as in lyotropic chromonic liquid crystals (LCLCs) (13,14).Reversible chromonic assembly and ensuing LCLC mesomorphism is displayed broadly by dyes, drugs (15-18), nucleotides (19,20), and DNA oligomers (21,22). Typically, the LCLC molecule is plank-like with aromatic cores and peripheral polar groups. In water, the polyaromatic cores stack face-to-face, forming elongated charged aggregates. The aggregates, self-assembled through weak noncovalent interactions, are polydisperse, with the length distribution that depends on concentration, temperature, ionic strength, and presence of crowding agents. At low concentrations, the aggregates are short and orient randomly. As the volume fraction increases, the aggregates elongate, multiply, and eventually some frac...

show abstract

Section: Resultsmentioning

confidence: 98%

mentioning

confidence: 99%

Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals

Tortora

Lavrentovich

2011

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

163

171

View full text Add to dashboard Cite

show abstract

“…[19,20]) and theoretically (e.g. [21][22][23][24][25]), theoretical models of 2D colloidal membranes are lacking.…”

Section: Previous Experimental Studies Of Colloidal Membranesmentioning

confidence: 99%

Theoretical calculation of the phase behavior of colloidal membranes

Yang

Hagan

2011

Phys. Rev. E

View full text Add to dashboard Cite

We formulate a density functional theory that describes the phase behavior of hard rods and depleting polymers, as realized in recent experiments on suspensions of fd virus and non-adsorbing polymer. The theory predicts the relative stability of nematic droplets, stacked smectic columns, and a recently discovered phase of isolated monolayers of rods, or colloidal membranes. We find that a minimum rod aspect ratio is required for stability of colloidal membranes and that collective protrusion undulations are the dominant effect that stabilizes this phase. The theoretical predictions are shown to be qualitatively consistent with experimental and computational results.

show abstract

“…Liquid crystals (LCs) are soft materials composed of anisotropic mesogens that provide remarkable examples of chiral symmetry breaking arising from elastic anisotropy (29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42). In essence, an LC can minimize elastic free energy by organizing its achiral units into chiral structures, such as helices and chiral layers, that incorporate twist deformation (7,8).…”

mentioning

confidence: 99%

“…Elasticity-driven chiral symmetry breaking is perhaps most readily manifested in confined LCs (31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43), wherein surface anchoring imposes a preferred angle for LC mesogens at the interface of the confining boundary. Topological defects enforced by boundary conditions can play a key role in the symmetry breaking as well, because energetically costly deformations are often concentrated in the vicinity of the defects (35)(36)(37).…”

mentioning

confidence: 99%

Chiral structures from achiral liquid crystals in cylindrical capillaries

Jeong

Kang

Davidson

et al. 2015

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

107

103

View full text Add to dashboard Cite

We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymercoated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects.mirror symmetry | parity symmetry | topological defects | chiral defects T he emergence of chirality from achiral systems poses fundamental questions about which we have limited mechanistic understanding (1-11). When the chiral symmetry of an achiral system is broken, a handedness is established, and materials with different handedness commonly exhibit distinct and useful properties (10-14) relevant for applications ranging from chemical sensors (15, 16) to photonics (17-19). To date, considerable effort has been expended to control handedness in materials (for example, by chiral separation of racemic mixtures or chiral amplification of small enantiomeric imbalances) (1,8,(20)(21)(22). Recently and in a different vein, identification and elucidation of pathways by which achiral building blocks spontaneously organize to create chiral structures have become an area of active study. Examples of these pathways include packing with multiple competing length scales (8-10, 23, 24), reconfiguration through mechanical instabilities of periodic structures (20,25,26), and helix formation of flexible cylinders through inter-and intracylinder interactions (27,28). In addition, the system of a broken chiral symmetry often consists of domains of opposite handedness with defects separating the domains.Liquid crystals (LCs) are soft materials composed ...

show abstract

Parity breaking in nematic tactoids

Cited by 44 publications

References 50 publications

Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals

Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals

Theoretical calculation of the phase behavior of colloidal membranes

Chiral structures from achiral liquid crystals in cylindrical capillaries

Contact Info

Product

Resources

About