Liquid Crystal Dispersions

Drzaic, Paul; Scheffer, T. J.

doi:10.1889/1.1985190

Cited by 260 publications

(455 citation statements)

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“…In contrast to the images shown in Figures 1A and 1D, these images reveal the presence of a single point defect located at the surface of the droplet (e.g., indicated by the white arrow in Figure 1B). The presence of this single point defect is consistent with a shift of the orientation of the LC from a bipolar configuration to a so-called preradial configuration, in which the director radiates outward from the single point defect (see Figure 1H for a schematic illustration) 38,48. Because the director profile for the preradial configuration is not spherically symmetric (that is, the point defect is not located in the center of the sphere), the apparent location of the defect changes as the droplet rotates in solution.…”

Section: Resultssupporting

confidence: 66%

“…These LC droplets exhibit a so-called bipolar configuration in which the director of the LC is oriented parallel to the surface of the droplets and connects two point defects located at opposite poles of the droplet 38,48 Figure 1G. presents a schematic illustration of this director profile.…”

Section: Resultsmentioning

confidence: 99%

“…Because the director profile for the preradial configuration is not spherically symmetric (that is, the point defect is not located in the center of the sphere), the apparent location of the defect changes as the droplet rotates in solution. This characteristic allows this type of defect to be identified easily and distinguished from the so-called radial configuration in which the defect is located in the geometric center of the LC droplet (and, thus, does not move as the droplet rotates; see Figure 1I for a schematic illustration of this configuration) 38,48. We observed radial configurations in bright-field images of LC droplets incubated in the presence of higher concentrations of polymer 1 (e.g., 1.0 mg/mL) as shown in Figure 1C.…”

Section: Resultsmentioning

confidence: 99%

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Immobilization of Polymer-Decorated Liquid Crystal Droplets on Chemically Tailored Surfaces

Kinsinger¹,

Buck²,

Abbott³

et al. 2010

Langmuir

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We demonstrate that the assembly of an amphiphilic polyamine on the interfaces of micrometersized droplets of a thermotropic liquid crystal (LC) dispersed in aqueous solutions can be used to facilitate the immobilization of LC droplets on chemically functionalized surfaces. Polymer 1 was designed to contain both hydrophobic (alkyl-functionalized) and hydrophilic (primary and tertiary amine-functionalized) side chain functionality. The assembly of this polymer at the interfaces of aqueous dispersions of LC droplets was achieved by spontaneous adsorption of polymer from aqueous solution. Polymer adsorption triggered transitions in the orientational ordering of the LCs, as observed by polarized light and bright-field microscopy. We demonstrate that the presence of polymer 1 on the interfaces of these droplets can be exploited to immobilize LC droplets on planar solid surfaces through covalent bond formation (e.g., for surfaces coated with polymer multilayers containing reactive azlactone functionality) or through electrostatic interactions (e.g., for surfaces coated with multilayers containing hydrolyzed azlactone functionality). Characterization of immobilized LC droplets by polarized, fluorescence, and laser scanning confocal microscopy revealed the general spherical shape of the polymer-coated LC droplets to be maintained after immobilization, and that immobilization led to additional ordering transitions within the droplets that was dependent on the nature of the surfaces with which they were in contact. Polymer 1-functionalized LC droplets were not immobilized on polymer multilayers treated with poly(ethylene imine) (PEI). We demonstrate that the ability to design surfaces that promote or prevent the immobilization of polymer-functionalized LC droplets can exploited to pattern the immobilization of LC droplets on surfaces. The results of this investigation provide the basis of an approach that could be used to tailor the properties of dispersed LC emulsions and to immobilize these droplets on functional surfaces of interest in a broad range of fundamental and applied contexts.

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Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Immobilization of Polymer-Decorated Liquid Crystal Droplets on Chemically Tailored Surfaces

Kinsinger¹,

Buck²,

Abbott³

et al. 2010

Langmuir

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show abstract

“…This observation has motivated a series of recent investigations, including studies of LC droplets, of the effects of confinement on the ordering of LCs. While a number of prior studies of LC emulsion systems have been reported,6, 70-73 a significant recent advance has been the preparation of a “LC-in-water” emulsion system in which precise control over both the size and interfacial chemistry of the LC droplets has been achieved 56-58. This system has yielded some observations of size-dependent ordering of nematic phases that were not anticipated based on prior theoretical developments or experimental studies 58…”

Section: Section 2: Aqueous Interfaces Of Thermotropic Liquid Crystalsmentioning

confidence: 99%

Recent Advances in Colloidal and Interfacial Phenomena Involving Liquid Crystals

2010

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This article describes recent advances in several areas of research involving the interfacial ordering of liquid crystals (LCs). The first advance revolves around the ordering of LCs at bio/ chemically functionalized surfaces. Whereas the majority of past studies of surface-induced ordering of LCs have involved surfaces of solids that present a limited diversity of chemical functional groups (surfaces at which van der Waals forces dominate surface-induced ordering), recent studies have moved to investigate the ordering of LCs on chemically complex surfaces. For example, surfaces decorated with biomolecules (e.g. oligopeptides and proteins) and transition metal ions have been investigated, leading to an understanding of the roles that metal-ligand coordination interactions, electrical double-layers, acid-base interactions, and hydrogen bonding can have on the interfacial ordering of LCs. The opportunity to create chemically-responsive LCs capable of undergoing ordering transitions in the presence of targeted molecular events (e.g., ligand exchange around a metal center) has emerged from these fundamental studies. A second advance has focused on investigations of the ordering of LCs at interfaces with immiscible isotropic fluids, particularly water. In contrast to prior studies of surface-induced ordering of LCs on solid surfaces, LC-aqueous interfaces are deformable and molecules at these interfaces exhibit high levels of mobility and thus can reorganize in response to changes in interfacial environment. A range of fundamental investigations involving these LC-aqueous interfaces have revealed that (i) the spatial and temporal characteristics of assemblies formed from biomolecular interactions can be reported by surface-driven ordering transitions in the LCs, (ii) the interfacial phase behaviour of molecules and colloids can be coupled to (and manipulated via) the ordering (and nematic elasticity) of LCs, and (iii) confinement of LCs leads to unanticipated size-dependent ordering (particularly in the context of LC emulsion droplets). The third and final advance addressed in this article involves interactions between colloids mediated by LCs. Recent experiments involving microparticles deposited at the LC-aqueous interface have revealed that LC-mediated interactions can drive interfacial assemblies of particles through reversible ordering transitions (e.g., from one-dimensional chains to two-dimensional arrays with local hexagonal symmetry). In addition, recent single nanoparticle measurements suggest that the ordering of LCs about nanoparticles differs substantially from micrometer-sized particles and that the interactions between nanoparticles mediated by the LCs are far weaker than predicted by theory (sufficiently weak that the interactions are reversible and thus enable self-assembly). Finally, LC-mediated interactions between colloidal particles have also been shown to lead to the formation of colloidin-LC gels that possess mechanical properties relevant to the design of materials to interface with li...

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“…Isotropic particles dispersed in liquid crystals have recently attracted increasing attention for their unique collective behavior leading to a rich variety of unusual colloidal structures [1]. In particular, isotropic (oil, water, or liquid crystal) droplets in nematic bulk phases [2][3][4] and droplets in smectic films [5][6][7][8][9][10][11][12][13][14][15][16] have been extensively investigated.…”

Section: Introductionmentioning

confidence: 99%

Self-organization of isotropic droplets in smectic-Cfree-standing films

Völtz

Stannarius

2004

Phys. Rev. E

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Free standing smectic films have been investigated at the transition from the smectic- C phase to the isotropic phase. In the vicinity of the bulk transition temperatures, isotropic droplets of micrometer size appear in the film. Such systems represent convenient models for anisotropic, two-dimensional emulsions. A characteristic feature of the droplets is their mutual interaction by elastic distortions of the local orientation of the film, the c director, which are related to the anchoring conditions of the c director at the droplet border. We describe in detail the director deformations created by isotropic droplets of different sizes, and their role in the spontaneous organization of regular droplet patterns. Depending upon droplet size and anchoring strength, topological defects can be induced in the c -director field. Qualitative differences to literature data on cholesteric droplets in smectic- C* films are discussed.

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Liquid Crystal Dispersions

Cited by 260 publications

References 0 publications

Immobilization of Polymer-Decorated Liquid Crystal Droplets on Chemically Tailored Surfaces

Immobilization of Polymer-Decorated Liquid Crystal Droplets on Chemically Tailored Surfaces

Recent Advances in Colloidal and Interfacial Phenomena Involving Liquid Crystals

Self-organization of isotropic droplets in smectic-Cfree-standing films

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