Coexistence of Two Colloidal Crystals at the Nematic-Liquid-Crystal–Air Interface

Nych, A.; Ognysta, U.; Pergamenshchik, V. M.; Lev, B. I.; Nazarenko, V. G.; Muševič, Igor; Škarabot, Miha; Lavrentovich, Oleg D.

doi:10.1103/physrevlett.98.057801

Cited by 89 publications

(68 citation statements)

References 20 publications

(21 reference statements)

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“…Past studies of the interactions of microdroplets confined at the interface of a LC have also found evidence of attractive interdroplet interactions (4)(5)(6)(7)(19)(20)(21)(22)(23). The attractive forces were initially attributed to a many-bodied "elastic-capillary" interaction between microdroplets (5,7,19,20).…”

Section: Resultsmentioning

confidence: 99%

“…When one of the isotropic liquids is replaced by a LC, it has recently become evident that additional mechanisms of interparticle interactions are realized. For example, glycerol microdroplets formed by condensation at a nematic LC-air interface have been reported to spontaneously self-assemble into two-dimensional assemblies with hexagonal symmetry (5)(6)(7)(8). In this paper, we report on the reversible ordering of solid microparticles, with chemically functionalized surfaces, at LC-aqueous interfaces.…”

Section: Colloidal Interactions | Interfacial Assemblies | Liquid Crymentioning

confidence: 99%

See 1 more Smart Citation

Chemoresponsive assemblies of microparticles at liquid crystalline interfaces

Koenig

Lin

Abbott

2010

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

108

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Assemblies formed by solid particles at interfaces have been widely studied because they serve as models of molecular phenomena, including molecular self-assembly. Solid particles adsorbed at interfaces also provide a means of stabilizing liquid-liquid emulsions and synthesizing materials with tunable mechanical, optical, or electronic properties. Whereas many past studies have investigated colloids at interfaces of isotropic liquids, recently, new types of intercolloidal interactions have been unmasked at interfaces of liquid crystals (LCs): The long-range ordering of the LCs, as well as defects within the LCs, mediates intercolloidal interactions with symmetries that differ from those observed with isotropic liquids. Herein, we report the decoration of interfaces formed between aqueous phases and nematic LCs with prescribed densities of solid, micrometer-sized particles. The microparticles assemble into chains with controlled interparticle spacing, consistent with the dipolar symmetry of the defects observed to form about each microparticle. Addition of a molecular surfactant to the aqueous phase results in a continuous ordering transition in the LC, which triggers reorganization of the microparticles, first by increasing the spacing between microparticles within chains and ultimately by forming two-dimensional arrays with local hexagonal symmetry. The ordering transition of the microparticles is reversible and is driven by surfactant-induced changes in the symmetry of the topological defects induced by the microparticles. These results demonstrate that the orderings of solid microparticles and molecular adsorbates are strongly coupled at the interfaces of LCs and that LCs offer the basis of methods for reversible, chemosensitive control of the interfacial organization of solid microparticles. colloidal interactions | interfacial assemblies | liquid crystals | ordering transitionsA liquid crystal (LC) is a phase of matter that blends properties that are typically associated with either crystalline solids or isotropic liquids (1). The molecules that comprise nematic LC phases exhibit long-range orientational order, yet they also possess mobilities characteristic of an isotropic liquid. LCs are most widely known for their use in electrooptic displays; however, they are increasingly being studied in the context of biology, materials science, and analytical chemistry (1). Recently, for example, microdroplets and microparticles dispersed in bulk LCs have been shown to form ordered assemblies, demonstrating that LCs can provide routes to stabilizing emulsions and assembling solid particles into colloidal crystals (2, 3). Although the origins of the interparticle forces that direct the formation of these assemblies in bulk LCs are not yet completely understood, it is clear that the long-range orientational ordering of molecules within the LC phase gives rise to interparticle forces that can be described in terms of the elasticity of the LCs and formation of topological defects within the LC. The LC-mediated interpart...

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Section: Resultsmentioning

confidence: 99%

Section: Colloidal Interactions | Interfacial Assemblies | Liquid Crymentioning

confidence: 99%

Chemoresponsive assemblies of microparticles at liquid crystalline interfaces

Koenig

Lin

Abbott

2010

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

108

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“…A rough estimate of the order of magnitude of the elastic energy associated with the director distortions around a strongly anchored micron-size particle placed in an otherwise uniform nematic cell, is 56 . Forces of the same nature are also responsible for attraction of colloidal particles to (particle-free) distortions and defects in the director field in nematics 47,57,58 , smectics [59][60][61] and blue phases 62 , for trapping and ordering of particles at the LC surfaces [63][64][65][66] , and even for symmetry-breaking that enables transport phenomena such as nonlinear electrophoresis in LCs 45,67 . As discussed in the next…”

Section: Surface Anchoring and Two Types Of Liquid Crystal Colloidsmentioning

confidence: 99%

“…Cell thickness d, m As follows from the consideration above, location of a particle in a LC is dictated not only by gravity and Brownian motion, as in an isotropic fluid, but also by the director field, its gradients, balance of elastic and surface anchoring forces, as in Fig.7, by geometry and properties of bounding walls and interfaces, Fig.4,5 63,64 , by presence of other particles 33 , etc. Spectacular effects of linking colloidal particles into clusters by disclination lines have been demonstrated by Ljubljana group 49,54 .…”

Section: Static Distortionsmentioning

confidence: 99%

Transport of particles in liquid crystals

2014

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“…13,14 Subsequently, it has also been observed that the glycerol droplets form the different lattices-hexagonal and dense quasihexagonal which can coexist and are separated by the energy barrier. 15 Yamamato et al 16 demonstrated photomechanical manipulation of glycerol droplets in NLCs on the basis of photoisomerization of azo-benzene derivative. But the mixing of glycerol in ferroelectric LC ͑FLC͒, which are well known for their good optical contrast, low threshold voltage, memory effect, fast response, etc., is rather far from investigations.…”

Section: Introductionmentioning

confidence: 99%

Dielectric and electro-optical studies of glycerol/ferroelectric liquid crystal mixture at room temperature

Kumar

Prakash

Choudhary

et al. 2009

Journal of Applied Physics

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The optical memory effect based on glycerol mixed deformed helix ferroelectric liquid crystal ͑DHFLC͒ material has been investigated. The observed memory effect has also been compared with the glycerol mixed ferroelectric liquid crystals ͑FLCs͒. The observance of memory effect has been verified by experimental data using dielectric spectroscopy, electro-optical, and textural studies under polarizing optical microscope. The glycerol not only helps to improve the memory effect in DHFLC material but also alters the physical parameters such as rotational viscosity, spontaneous polarization, response time, etc. too in both glycerol/DHFLC and glycerol/FLC mixtures.

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Coexistence of Two Colloidal Crystals at the Nematic-Liquid-Crystal–Air Interface

Cited by 89 publications

References 20 publications

Chemoresponsive assemblies of microparticles at liquid crystalline interfaces

Chemoresponsive assemblies of microparticles at liquid crystalline interfaces

Transport of particles in liquid crystals

Dielectric and electro-optical studies of glycerol/ferroelectric liquid crystal mixture at room temperature

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