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Kim J, Jeong J. Confinement twists achiral liquid crystals and causes chiral liquid crystals to twist in the opposite handedness: cases in and around sessile droplets. SOFT MATTER 2024; 20:1361-1368. [PMID: 38252544 DOI: 10.1039/d3sm01283b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
We study the chiral symmetry breaking and metastability of confined nematic lyotropic chromonic liquid crystals (LCLCs) with and without chiral dopants. The isotropic-nematic coexistence phase of the LCLC renders two confining geometries: sessile isotropic (I) droplets surrounded by the nematic (N) phase and sessile nematic droplets immersed in the isotropic background. In the achiral system with no dopants, LCLC's elastic anisotropy and topological defects induce a spontaneous twist deformation to lower the energetic penalty of splay deformation, resulting in spiral optical textures under crossed polarizers both in the I-in-N and N-in-I systems. While the achiral system exhibits both handednesses with an equal probability, a small amount of the chiral dopant breaks the balance. Notably, in contrast to the homochiral configuration of a chirally doped LCLC in the bulk, the spiral texture of the disfavored handedness appears with a finite probability both in the I-in-N and N-in-I systems. We propose director field models explaining how chiral symmetry breaking arises by the energetics and the opposite-twist configurations exist as meta-stable structures in the energy landscape. These findings help us create and control chiral structures using confined LCs with large elastic anisotropy.
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Affiliation(s)
- Jungmyung Kim
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
| | - Joonwoo Jeong
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
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2
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Zhang Q, Wang W, Zhou S, Zhang R, Bischofberger I. Flow-induced periodic chiral structures in an achiral nematic liquid crystal. Nat Commun 2024; 15:7. [PMID: 38191525 PMCID: PMC10774319 DOI: 10.1038/s41467-023-43978-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 11/26/2023] [Indexed: 01/10/2024] Open
Abstract
Supramolecular chirality typically originates from either chiral molecular building blocks or external chiral stimuli. Generating chirality in achiral systems in the absence of a chiral input, however, is non-trivial and necessitates spontaneous mirror symmetry breaking. Achiral nematic lyotropic chromonic liquid crystals have been reported to break mirror symmetry under strong surface or geometric constraints. Here we describe a previously unrecognised mechanism for creating chiral structures by subjecting the material to a pressure-driven flow in a microfluidic cell. The chirality arises from a periodic double-twist configuration of the liquid crystal and manifests as a striking stripe pattern. We show that the mirror symmetry breaking is triggered at regions of flow-induced biaxial-splay configurations of the director field, which are unstable to small perturbations and evolve into lower energy structures. The simplicity of this unique pathway to mirror symmetry breaking can shed light on the requirements for forming macroscopic chiral structures.
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Affiliation(s)
- Qing Zhang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Weiqiang Wang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Shuang Zhou
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Rui Zhang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China.
| | - Irmgard Bischofberger
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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3
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Ettinger S, Dietrich CF, Mishra CK, Miksch C, Beller DA, Collings PJ, Yodh AG. Rods in a lyotropic chromonic liquid crystal: emergence of chirality, symmetry-breaking alignment, and caged angular diffusion. SOFT MATTER 2022; 18:487-495. [PMID: 34851348 DOI: 10.1039/d1sm01209f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In lyotropic chromonic liquid crystals (LCLCs), twist distortion of the nematic director costs much less energy than splay or bend distortion. This feature leads to novel mirror-symmetry breaking director configurations when the LCLCs are confined by interfaces or contain suspended particles. Spherical colloids in an aligned LCLC nematic phase, for example, induce chiral director perturbations ("twisted tails"). The asymmetry of rod-like particles in an aligned LCLC offer a richer set of possibilities due to their aspect ratio (α) and mean orientation angle (〈θ〉) between their long axis and the uniform far-field director. Here we report on the director configuration, equilibrium orientation, and angular diffusion of rod-like particles with planar anchoring suspended in an aligned LCLC. Video microscopy reveals, counterintuitively, that two-thirds of the rods have an angled equilibrium orientation (〈θ〉 ≠ 0) that decreases with increasing α, while only one-third of the rods are aligned (〈θ〉 = 0). Polarized optical video-microscopy and Landau-de Gennes numerical modeling demonstrate that the angled and aligned rods are accompanied by distinct chiral director configurations. Angled rods have a longitudinal mirror plane (LMP) parallel to their long axis and approximately parallel to the substrate walls. Aligned rods have a transverse and longitudinal mirror plane (TLMP), where the transverse mirror plane is perpendicular to the rod's long axis. Effectively, the small twist elastic constant of LCLCs promotes chiral director configurations that modify the natural tendency of rods to orient along the far-field director. Additional diffusion experiments confirm that rods are angularly confined with strength that depends on α.
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Affiliation(s)
- Sophie Ettinger
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Clarissa F Dietrich
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Chandan K Mishra
- Discipline of Physics, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gandhinagar, Gujarat 382355, India
| | - Cornelia Miksch
- Max Planck Institute of Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Daniel A Beller
- Department of Physics, University of California, Merced, CA, 95343, USA
| | - Peter J Collings
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA, 19081, USA
| | - A G Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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4
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Nych A, Kravchuk R, Ognysta U, Ledney M, Yaroshchuk O. Double-twisted nematic director configurations in cylindrical capillaries with a photocontrollable angle of twist. Phys Rev E 2021; 104:054703. [PMID: 34942696 DOI: 10.1103/physreve.104.054703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/01/2021] [Indexed: 11/07/2022]
Abstract
The orientational configurations of thermotropic nematic liquid crystal in cylindrical capillaries with nondegenerated planar surface anchoring are investigated. The boundary conditions were determined by a photoaligning coating on the inner wall of the capillary treated with a linearly polarized UV light while rotating the capillary around its long axis, thus providing the easy alignment axis perpendicular to the polarization direction of illuminating light. By changing the angle between the incident light polarization and the capillary axis, this procedure allows us to realize axially symmetric twisted structure with any angle of twist, ranging from a trivial axial alignment with zero twist (when the UV polarization is perpendicular to the capillary axis) to the 180^{∘}-twisted configuration (when the UV polarization is along the capillary). These two extreme configurations together with an intermediate configuration induced by UV light polarized at an angle of 45^{∘} to the capillary axis were produced and their director profiles were studied using polarizing microscopy techniques. UV light intensity and polarization distribution over inner capillary surface covered with photoaligning layer were analyzed using optical ray tracing calculations. An analytical model of the observed configurations of the liquid crystal director field is proposed, which takes into account the finite anchoring on the capillary surface. By comparing the theoretically calculated and experimentally estimated director profiles, the liquid crystal anchoring energy on the photoaligned capillary surface was estimated.
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Affiliation(s)
- A Nych
- Department of Molecular Photoelectronics, Institute of Physics, Prospect Nauky 46, 03680 Kyiv, Ukraine.,Condensed Matter Physics Department, J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - R Kravchuk
- Department of Physics of Crystals, Institute of Physics, Prospect Nauky 46, 03680 Kyiv, Ukraine
| | - U Ognysta
- Department of Molecular Photoelectronics, Institute of Physics, Prospect Nauky 46, 03680 Kyiv, Ukraine
| | - M Ledney
- Faculty of Physics, Taras Shevchenko National University of Kyiv, Academician Glushkov Avenue 4, 03680 Kyiv, Ukraine
| | - O Yaroshchuk
- Department of Physics of Crystals, Institute of Physics, Prospect Nauky 46, 03680 Kyiv, Ukraine
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5
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Jani P, Nayani K, Abbott NL. Sculpting the shapes of giant unilamellar vesicles using isotropic-nematic-isotropic phase cycles. SOFT MATTER 2021; 17:9078-9086. [PMID: 34558596 DOI: 10.1039/d1sm00910a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding how soft matter deforms in response to mechanical interactions is central to the design of functional synthetic materials as well as elucidation of the behaviors of biological assemblies. Here we explore how cycles of thermally induced transitions between nematic (N) and isotropic (I) phases can be used to exert cyclical elastic stresses on dispersions of giant unilamellar vesicles (GUVs) and thereby evolve GUV shape and properties. The measurements were enabled by the finding that I-N-I phase transitions of the lyotropic chromonic liquid crystal disodium cromoglycate, when conducted via an intermediate columnar (M) phase, minimized transport of GUVs on phase fronts to confining surfaces. Whereas I to N phase transitions strained spherical GUVs into spindle-like shapes, with an efflux of GUV internal volume, subsequent N to I transitions generated a range of complex GUV shapes, including stomatocyte, pear- and dumbbell-like shapes that depended on the extent of strain in the N phase. The highest strained GUVs were observed to form buds (daughter vesicles) that we show, via a cycle of I-N-I-N phase transitions, are connected via a neck to the parent vesicle. Additional experiments established that changes in elasticity of the phase surrounding the GUVs and not thermal expansion of membranes were responsible for the shape transitions, and that I-N-I transformations that generate stomatocytes can be understood from the Bilayer-Coupling model of GUV shapes. Overall, these observations advance our understanding of how LC elastic stresses can be regulated to evolve the shapes of soft biological assemblies as well as provide new approaches for engineering synthetic soft matter.
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Affiliation(s)
- Purvil Jani
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
| | - Karthik Nayani
- Department of Chemical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Nicholas L Abbott
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
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6
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Dietrich CF. Lyotropic nematic liquid crystals: interplay between a small twist elastic constant and chirality effects under confined geometries. LIQUID CRYSTALS TODAY 2021. [DOI: 10.1080/1358314x.2021.1928961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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7
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Park G, Čopar S, Suh A, Yang M, Tkalec U, Yoon DK. Periodic Arrays of Chiral Domains Generated from the Self-Assembly of Micropatterned Achiral Lyotropic Chromonic Liquid Crystal. ACS CENTRAL SCIENCE 2020; 6:1964-1970. [PMID: 33274273 PMCID: PMC7706096 DOI: 10.1021/acscentsci.0c00995] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Indexed: 05/20/2023]
Abstract
Achiral building blocks forming achiral structures is a common occurrence in nature, while chirality emerging spontaneously from an achiral system is usually associated with important scientific phenomena. We report on the spontaneous chiral symmetry-breaking phenomena upon the topographic confinement of achiral lyotropic chromonic liquid crystals in periodically arranged micrometer scale air pillars. The anisotropic fluid arranges into chiral domains that depend on the arrangement and spacing of the pillars. We characterize the resulting domains by polarized optical microscopy, support their reconstruction by numerical calculations, and extend the findings with experiments, which include chiral dopants. Well-controlled and addressed chiral structures will be useful in potential applications like programmable scaffolds for living liquid crystals and as sensors for detecting chirality at the molecular level.
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Affiliation(s)
- Geonhyeong Park
- Graduate
School of Nanoscience and Technology, Korea
Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Simon Čopar
- Faculty
of Mathematics and Physics, University of
Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
| | - Ahram Suh
- Graduate
School of Nanoscience and Technology, Korea
Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Minyong Yang
- Graduate
School of Nanoscience and Technology, Korea
Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Uroš Tkalec
- Institute
of Biophysics, Faculty of Medicine, University
of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
- Faculty
of Natural Sciences and Mathematics, University
of Maribor, Koroška
160, 2000 Maribor, Slovenia
- Department
of Condensed Matter Physics, Jožef
Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- E-mail: (U. Tkalec)
| | - Dong Ki Yoon
- Graduate
School of Nanoscience and Technology, Korea
Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
- Department
of Chemistry and KINC, Korea Advanced Institute
of Science and Technology, Daejeon 34141, Republic of Korea
- E-mail: (D.K. Yoon)
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8
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Čopar S, Kos Ž, Emeršič T, Tkalec U. Microfluidic control over topological states in channel-confined nematic flows. Nat Commun 2020; 11:59. [PMID: 31896755 PMCID: PMC6940393 DOI: 10.1038/s41467-019-13789-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 11/28/2019] [Indexed: 12/02/2022] Open
Abstract
Compared to isotropic liquids, orientational order of nematic liquid crystals makes their rheological properties more involved, and thus requires fine control of the flow parameters to govern the orientational patterns. In microfluidic channels with perpendicular surface alignment, nematics discontinuously transition from perpendicular structure at low flow rates to flow-aligned structure at high flow rates. Here we show how precise tuning of the driving pressure can be used to stabilize and manipulate a previously unresearched topologically protected chiral intermediate state which arises before the homeotropic to flow-aligned transition. We characterize the mechanisms underlying the transition and construct a phenomenological model to describe the critical behaviour and the phase diagram of the observed chiral flow state, and evaluate the effect of a forced symmetry breaking by introduction of a chiral dopant. Finally, we induce transitions on demand through channel geometry, application of laser tweezers, and careful control of the flow rate. It is interesting phenomenon that chiral order can emerge in intrinsically achiral liquid crystals. Here Čopar et al. demonstrate achiral-to-chiral transition of the nematic liquid crystals flow in microfluidic channels and their behaviour, stability, and dependence on geometric and material parameters.
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Affiliation(s)
- Simon Čopar
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
| | - Žiga Kos
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
| | - Tadej Emeršič
- Faculty of Medicine, Institute of Biophysics, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia.,Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Uroš Tkalec
- Faculty of Medicine, Institute of Biophysics, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia. .,Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia. .,Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000, Maribor, Slovenia.
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9
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Thermo-Optical Generation of Particle-Like Structures in Frustrated Chiral Nematic Film. CRYSTALS 2019. [DOI: 10.3390/cryst9110574] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The creation of metastable particle-like structures in frustrated (unwound) chiral nematic film containing light-absorbing additive is studied. It is shown that such localized structures can be generated by the thermo-optical action of a focused laser beam or arise spontaneously at a phase transition from an isotropic to a liquid crystal state. Observed axisymmetric patterns resemble cholesteric spherulites with toroidal double-twisted director-field configuration.
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10
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Martinez A, Collings PJ, Yodh AG. Brownian Dynamics of Particles "Dressed" by Chiral Director Configurations in Lyotropic Chromonic Liquid Crystals. PHYSICAL REVIEW LETTERS 2018; 121:177801. [PMID: 30411945 DOI: 10.1103/physrevlett.121.177801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Indexed: 06/08/2023]
Abstract
We study Brownian dynamics of colloidal spheres, with planar anchoring conditions, suspended in the nematic phase of the lyotropic chromonic liquid crystal disodium chromoglycate (DSCG). Unlike typical liquid crystals, the unusually small twist elastic modulus of DSCG permits two energetically distinct helical distortions (twisted tails) of the nematic director to "dress" the suspended spheres. Video microscopy is used to characterize the helical distortions versus particle size and to measure particle mean-square displacements. Diffusion coefficients parallel and perpendicular to the far-field director, and their anisotropy ratio, are different for the two twisted tail configurations. Moreover, the crossover from subdiffusive to diffusive behavior is anomalously slow for motion perpendicular to the director (>100 s). Simple arguments using Miesowicz viscosities and ideas about twist relaxation are suggested to understand the mean-square displacement observations.
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Affiliation(s)
- Angel Martinez
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Peter J Collings
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, Pennsylvania 19081, USA
| | - A G Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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11
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Affiliation(s)
- Emanuele Romani
- Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma, Italy
| | - Alberta Ferrarini
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Cristiano De Michele
- Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma, Italy
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12
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Dietrich CF, Rudquist P, Lorenz K, Giesselmann F. Chiral Structures from Achiral Micellar Lyotropic Liquid Crystals under Capillary Confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5852-5862. [PMID: 28509558 DOI: 10.1021/acs.langmuir.7b01074] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recently, the emergence of spontaneous reflection-symmetry-broken configurations in achiral chromonic liquid crystals confined in cylindrical capillaries with homeotropic anchoring at the cylinder walls was reported, namely, the so-called twisted-escaped radial (TER) and twisted planar polar (TPP) configurations. This new example of spontaneous reflection symmetry breaking in liquid crystals was attributed to the twist elastic modulus, which is known to be unusually small in comparison to the splay and bend moduli in the case of chromonic liquid crystals. We now report the experimental observation of reflection symmetry breaking in cylindrical capillaries in the case of a classical, achiral, and nonchromonic lyotropic liquid crystal forming a nematic phase of disklike micelles orienting homeotropically at the capillary walls. We observed the same chiral TER configuration, as well as a nonplanar twisted polar (TP) configuration. The TP configuration is characterized by two half-unit so-called twist disclinations, where the director twist around the line defects drives the formation of a double helix of the disclinations along the axis of the capillary. Additionally, there is a transverse twist between the two disclination lines with the same handedness as the axial twist. Similarities with and differences from the case of chromonic liquid crystals are discussed; in particular, we examine the conditions under which spontaneous reflection symmetry breaking occurs in the nonchromonic system. It seems that the chiral TER configuration can be stabilized by the presence of point defects.
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Affiliation(s)
- Clarissa F Dietrich
- Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Per Rudquist
- Microelectronics and Nanoscience, Chalmers University of Technology , 41296 Göteborg, Sweden
| | - Kristin Lorenz
- Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
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13
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Abstract
Fractals are remarkable examples of self-similarity where a structure or dynamic pattern is repeated over multiple spatial or time scales. However, little is known about how fractal stimuli such as fractal surfaces interact with their local environment if it exhibits order. Here we show geometry-induced formation of fractal defect states in Koch nematic colloids, exhibiting fractal self-similarity better than 90% over three orders of magnitude in the length scales, from micrometers to nanometres. We produce polymer Koch-shaped hollow colloidal prisms of three successive fractal iterations by direct laser writing, and characterize their coupling with the nematic by polarization microscopy and numerical modelling. Explicit generation of topological defect pairs is found, with the number of defects following exponential-law dependence and reaching few 100 already at fractal iteration four. This work demonstrates a route for generation of fractal topological defect states in responsive soft matter.
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14
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Abstract
Liquid crystals (LCs), because of their long-range molecular ordering, are anisotropic, elastic fluids. Herein, we report that elastic stresses imparted by nematic LCs can dynamically shape soft colloids and tune their physical properties. Specifically, we use giant unilamellar vesicles (GUVs) as soft colloids and explore the interplay of mechanical strain when the GUVs are confined within aqueous chromonic LC phases. Accompanying thermal quenching from isotropic to LC phases, we observe the elasticity of the LC phases to transform initially spherical GUVs (diameters of 2-50 µm) into two distinct populations of GUVs with spindle-like shapes and aspect ratios as large as 10. Large GUVs are strained to a small extent (R/r < 1.54, where R and r are the major and minor radii, respectively), consistent with an LC elasticity-induced expansion of lipid membrane surface area of up to 3% and conservation of the internal GUV volume. Small GUVs, in contrast, form highly elongated spindles (1.54 < R/r < 10) that arise from an efflux of LCs from the GUVs during the shape transformation, consistent with LC-induced straining of the membrane leading to transient membrane pore formation. A thermodynamic analysis of both populations of GUVs reveals that the final shapes adopted by these soft colloids are dominated by a competition between the LC elasticity and an energy (∼0.01 mN/m) associated with the GUV-LC interface. Overall, these results provide insight into the coupling of strain in soft materials and suggest previously unidentified designs of LC-based responsive and reconfigurable materials.
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15
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Zhang B, Kitzerow HS. Influence of Proton and Salt Concentration on the Chromonic Liquid Crystal Phase Diagram of Disodium Cromoglycate Solutions: Prospects and Limitations of a Host for DNA Nanostructures. J Phys Chem B 2016; 120:3250-6. [PMID: 26964003 DOI: 10.1021/acs.jpcb.6b01644] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lyotropic chromonic liquid crystals have recently been suggested for use as a self-organized host for dispersing and aligning self-organized DNA origami nanostructures. However, an appropriate pH value and a suitable cation concentration are necessary to stabilize such nanostructures and to avoid unfolding of the DNA. The present study shows that the nematic and columnar liquid crystal phases appearing in aqueous solutions of disodium cromoglycate are robust against the replacement of deionized water by a neutral or alkaline buffer solution. However, disodium cromoglycate precipitates when an acidic buffer is used or when the concentration of magnesium cations exceeds a critical concentration of about 0.6-0.7 mmol/L.
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Affiliation(s)
- Bingru Zhang
- Department of Chemistry, University of Paderborn , Warburger Strasse 100, 33098 Paderborn, Germany
| | - Heinz-S Kitzerow
- Department of Chemistry, University of Paderborn , Warburger Strasse 100, 33098 Paderborn, Germany
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16
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Martens K, Funck T, Kempter S, Roller EM, Liedl T, Blaschke BM, Knecht P, Garrido JA, Zhang B, Kitzerow H. Alignment and Graphene-Assisted Decoration of Lyotropic Chromonic Liquid Crystals Containing DNA Origami Nanostructures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:1658-1666. [PMID: 26849188 DOI: 10.1002/smll.201503382] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/18/2015] [Indexed: 06/05/2023]
Abstract
Composites of DNA origami nanostructures dispersed in a lyotropic chromonic liquid crystal are studied by polarizing optical microscopy. The homogeneous aqueous dispersions can be uniformly aligned by confinement between two glass substrates, either parallel to the substrates owing to uniaxial rubbing or perpendicular to the substrates using ozonized graphene layers. These opportunities of uniform alignment may pave the way for tailored anisometric plasmonic DNA nanostructures to photonic materials. In addition, a decorated texture with nonuniform orientation is observed on substrates coated with pristine graphene. When the water is allowed to evaporate slowly, microscopic crystal needles appear, which are aligned along the local orientation of the director. This decoration method can be used for studying the local orientational order and the defects in chromonic liquid crystals.
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Affiliation(s)
- Kevin Martens
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539, München, Germany
| | - Timon Funck
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539, München, Germany
| | - Susanne Kempter
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539, München, Germany
| | - Eva-Maria Roller
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539, München, Germany
| | - Tim Liedl
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539, München, Germany
| | - Benno M Blaschke
- Walter Schottky Institut and Physics Department, Technische Universität München, Am Coulombwall 4, 85748, Garching, Germany
| | - Peter Knecht
- Walter Schottky Institut and Physics Department, Technische Universität München, Am Coulombwall 4, 85748, Garching, Germany
| | - José Antonio Garrido
- Walter Schottky Institut and Physics Department, Technische Universität München, Am Coulombwall 4, 85748, Garching, Germany
| | - Bingru Zhang
- Faculty of Science, Department of Chemistry, University of Paderborn, Warburger Straße 100, 33098, Paderborn, Germany
| | - Heinz Kitzerow
- Faculty of Science, Department of Chemistry, University of Paderborn, Warburger Straße 100, 33098, Paderborn, Germany
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17
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Čopar S, Seč D, Aguirre LE, Almeida PL, Dazza M, Ravnik M, Godinho MH, Pieranski P, Žumer S. Sensing and tuning microfiber chirality with nematic chirogyral effect. Phys Rev E 2016; 93:032703. [PMID: 27078423 DOI: 10.1103/physreve.93.032703] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Indexed: 06/05/2023]
Abstract
Microfibers with their elongated shape and translation symmetry can act as important components in various soft materials, notably for their mechanics on the microscopic level. Here we demonstrate the mechanical response of a micro-object to imposed chirality, in this case, the tilt of disclination rings in an achiral nematic medium caused by the chiral surface anchoring on an immersed microfiber. This coupling between chirality and mechanical response, used to demonstrate sensing of chirality of electrospun cellulose microfibers, is revealed in the optical micrographs due to anisotropy in the elastic response of the host medium. We provide an analytical explanation of the chirogyral effect supported with numerical simulations and perform an experiment to test the effect of the cell confinement and fiber size. We controllably twist the microfibers and demonstrate the response of the nematic medium. More generally the demonstrated study provides means for experimental discrimination of surface properties and allows mechanical control over the shape of disclination rings.
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Affiliation(s)
- Simon Čopar
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
| | - David Seč
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
| | - Luis E Aguirre
- CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal
| | - Pedro L Almeida
- CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal
- Área Departamental de Física, Instituto Superior de Engenharia de Lisboa, ISEL, Instituto Politécnico de Lisboa, R. Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal
| | - Mallory Dazza
- Laboratoire de Physique des Solides, UMR 8502, Université Paris-Sud, Bât. 510, 91405 Orsay, France
- École normale supérieure de Cachan, 61, avenue du Président Wilson, 94235 Cachan, France
| | - Miha Ravnik
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
- J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Maria H Godinho
- CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal
| | - Pawel Pieranski
- Laboratoire de Physique des Solides, UMR 8502, Université Paris-Sud, Bât. 510, 91405 Orsay, France
| | - Slobodan Žumer
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
- J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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18
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Senyuk B, Pandey MB, Liu Q, Tasinkevych M, Smalyukh II. Colloidal spirals in nematic liquid crystals. SOFT MATTER 2015; 11:8758-8767. [PMID: 26358649 DOI: 10.1039/c5sm01539a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry. Colloidal particles also exhibit both stable and metastable multiple orientational states in the nematic host, with a large number of director configurations featuring both singular and solitonic nonsingular topological defects accompanying them, which can result in unusual forms of colloidal self-assembly. Our findings directly demonstrate how the symmetry of particle-generated director configurations can be further lowered, or not, as compared to the low point group symmetry of solid micro-inclusions, depending on the nature of induced defects while satisfying topological constraints. We show that achiral colloidal particles can cause chiral symmetry breaking of elastic distortions, which is driven by complex three-dimensional winding of induced topological line defects and solitons.
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Affiliation(s)
- Bohdan Senyuk
- Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| | - Manoj B Pandey
- Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| | - Qingkun Liu
- Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| | - Mykola Tasinkevych
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, D-70569 Stuttgart, Germany and IV. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado, Boulder, CO 80309, USA. and Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309, USA
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Peng C, Lavrentovich OD. Chirality amplification and detection by tactoids of lyotropic chromonic liquid crystals. SOFT MATTER 2015; 11:7257-63. [PMID: 26238525 DOI: 10.1039/c5sm01632k] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Detection of chiral molecules requires amplification of chirality to measurable levels. Typically, amplification mechanisms are considered at the microscopic scales of individual molecules and their aggregates. Here we demonstrate chirality amplification and visualization of structural handedness in water solutions of organic molecules that extends over the scale of many micrometers. The mechanism is rooted in the long-range elastic nature of orientational order in lyotropic chromonic liquid crystals (LCLCs) formed in water solutions of achiral disc-like molecules. The nematic LCLC coexists with its isotropic counterpart, forming elongated tactoids; the spatial confinement causes a structural twist even when the material is nonchiral. Minute quantities of chiral molecules such as the amino acid l-alanine and limonene transform the racemic array of left- and right-twisted tactoids into a homochiral set. The left and right chiral enantiomers are readily distinguished from each other as the induced structural handedness is visualized through a simple polarizing microscope observation. The effect is important for developing our understanding of chirality amplification mechanisms; it also might open up new possibilities in biosensing.
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Affiliation(s)
- Chenhui Peng
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
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20
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Tovkach OM, Chernyshuk SB, Lev BI. Colloidal interactions in a homeotropic nematic cell with different elastic constants. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042505. [PMID: 26565263 DOI: 10.1103/physreve.92.042505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 06/05/2023]
Abstract
We propose a theoretical description of the interaction mediated by a nematic-liquid-crystal host with different Frank elastic constants. A general expression for the energy of such an interaction between colloidal particles of arbitrary size and shape suspended in a homeotropic cell is obtained. In the cells of large thickness, the presented potential converges to that found previously for small particles in the nematic bulk. In general, our results confirm the validity of the one-constant approximation for weakly elastically anisotropic nematic liquid crystals. For nematics with a high splay-to-bend ratio we predict a larger range of the interaction. Using the dependence of this range on the elastic constants, we show that there exists a qualitative similarity between the interactions in a nematic and in a smectic-A phase. It manifests itself, in particular, in a decrease of the angle between a chain of quadrupole particles and the uniform far-field director across a nematic-smectic-A phase transition. We also demonstrate that the anisotropy of the elastic constants can lead to the formation of thermodynamically stable linear superstructures of asymmetric particles (elastic monopoles) with large, compared to usual dipole chains, interparticle distances.
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Affiliation(s)
- O M Tovkach
- Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, Metrologichna 14-b, Kyiv 03680,Ukraine
| | - S B Chernyshuk
- Institute of Physics, NAS of Ukraine, Prospekt Nauky 46, Kyiv 03650, Ukraine
| | - B I Lev
- Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, Metrologichna 14-b, Kyiv 03680,Ukraine
- Department of Physics, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon 305-764, Korea
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21
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Mushenheim PC, Trivedi RR, Roy SS, Arnold MS, Weibel DB, Abbott NL. Effects of confinement, surface-induced orientations and strain on dynamical behaviors of bacteria in thin liquid crystalline films. SOFT MATTER 2015; 11:6821-6831. [PMID: 26224035 PMCID: PMC6365283 DOI: 10.1039/c5sm01489a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report on the organization and dynamics of bacteria (Proteus mirabilis) dispersed within lyotropic liquid crystal (LC) films confined by pairs of surfaces that induce homeotropic (perpendicular) or hybrid (homeotropic and parallel orientations at each surface) anchoring of the LC. By using motile vegetative bacteria (3 µm in length) and homeotropically aligned LC films with thicknesses that exceed the length of the rod-shaped cells, a key finding reported in this paper is that elastic torques generated by the LC are sufficiently large to overcome wall-induced hydrodynamic torques acting on the cells, thus leading to LC-guided bacterial motion near surfaces that orient LCs. This result extends to bacteria within LC films with hybrid anchoring, and leads to the observation that asymmetric strain within a hybrid aligned LC rectifies motions of motile cells. In contrast, when the LC film thickness is sufficiently small that confinement prevents alignment of the bacteria cells along a homeotropically aligned LC director (achieved using swarm cells of length 10-60 µm), the bacterial cells propel in directions orthogonal to the director, generating transient distortions in the LC that have striking "comet-like" optical signatures. In this limit, for hybrid LC films, we find LC elastic stresses deform the bodies of swarm cells into bent configurations that follow the LC director, thus unmasking a coupling between bacterial shape and LC strain. Overall, these results provide new insight into the influence of surface-oriented LCs on dynamical bacterial behaviors and hint at novel ways to manipulate bacteria using confined LC phases that are not possible in isotropic solutions.
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Affiliation(s)
- Peter C. Mushenheim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA. ; Fax: +1-608-262-5434; Tel: +1-608-265-5278
| | - Rishi R. Trivedi
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive,Madison, WI, 53706, USA. Fax: +1-608-265-0764; Tel: +1-608-890-1342
| | - Susmit Singha Roy
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, WI, 53706, USA. Fax: +1-608-262-8353;Tel: +1-608-262-3863
| | - Michael S. Arnold
- Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, WI, 53706, USA. Fax: +1-608-262-8353;Tel: +1-608-262-3863
| | - Douglas B. Weibel
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive,Madison, WI, 53706, USA. Fax: +1-608-265-0764; Tel: +1-608-890-1342
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA. ; Fax: +1-608-262-5434; Tel: +1-608-265-5278
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22
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Zimmermann N, Jünnemann-Held G, Collings PJ, Kitzerow HS. Self-organized assemblies of colloidal particles obtained from an aligned chromonic liquid crystal dispersion. SOFT MATTER 2015; 11:1547-1553. [PMID: 25589441 DOI: 10.1039/c4sm02579b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The behavior of mono-disperse colloidal particles in a chromonic liquid crystal was investigated. Poly(methyl methacrylate) spherical particles with three different functionalizations, with and without surface charges, were utilized in the nematic and columnar phases of disodium cromoglycate solutions. The nematic phase was completely aligned parallel to the glass substrates by a simple rubbing technique, and the columnar phase showed regions of similar alignment. The behavior of the colloidal particles in the chromonic liquid crystal depended critically on the functionality, with bromine functionalized particles not dispersing at all, and cationic trimethylammonium and epoxy functionalized particles dispersing well in the isotropic phase of the liquid crystal. At the transition to the nematic and especially the columnar phase, the colloidal particles were expelled into the remaining isotropic phase. Since the columnar phase grew in parallel ribbons, the colloidal particles ended up in chain-like assemblies. Such behavior opens the possibility of producing patterned assemblies of colloidal particles by taking advantage of the self-organized structure of chromonic liquid crystals.
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Affiliation(s)
- Natalie Zimmermann
- Department of Chemistry, University of Paderborn, 33098 Paderborn, Germany.
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Mushenheim PC, Abbott NL. Hierarchical organization in liquid crystal-in-liquid crystal emulsions. SOFT MATTER 2014; 10:8627-8634. [PMID: 25278032 PMCID: PMC4241356 DOI: 10.1039/c4sm01651c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report the formation and characterization of hierarchical ordering in systems comprised of micrometer-sized droplets of thermotropic nematic liquid crystals (LCs) dispersed in continuous nematic phases of a lyotropic chromonic LC (disodium cromoglycate (DSCG)). Significantly, we find the orientations of the two LC phases to be coupled, with nematic droplets of 4'-pentyl-4-cyanobiphenyl (5CB) exhibiting a bipolar configuration with an axis of symmetry aligned orthogonal to the far-field director of the DSCG phase. We determine that this coupling of orientations does not result from either anisometric LC droplet shape or interfacial ionic phenomena but rather is consistent with the influence of van der Waals interactions that arise from the anisotropic polarizabilities of nematic 5CB (Δn = +0.18) and DSCG (Δn = -0.02) phases. We also find that it is possible to rotate and uniformly align the nematic droplets by using a weak magnetic field (B ∼ 0.3 T). An analysis of the dynamics of relaxation of the orientations of the 5CB droplets following removal of the magnetic field reveals the DSCG and 5CB droplets to be coupled by energies of ∼10(4) kT, consistent with a simple theoretical estimate of the influence of anisotropic van der Waals interactions. We also observed the nematic 5CB droplets to form dimers and larger assemblies mediated by the elasticity of the nematic DSCG. Overall, these results reveal that LC-in-LC emulsions define a new class of hierarchically ordered soft matter in which both thermotropic and lyotropic LCs are coupled in their ordering.
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Affiliation(s)
- Peter C Mushenheim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706, USA.
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