Morphogenesis of defects and tactoids during isotropic–nematic phase transition in self-assembled lyotropic chromonic liquid crystals

Kim, Young-Ki; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

doi:10.1088/0953-8984/25/40/404202

Cited by 124 publications

(230 citation statements)

References 88 publications

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“…4A leads to the somewhat surprising conclusion that the interfacial energy of nonspherical GUVs in the LC is not dominated by an energy penalty associated with stretching of the GUV membrane but rather, is dominated by a strain-independent surface energy arising from the presence of an interface between the nematic DSCG and GUV membrane. Moreover, τ exp has a magnitude similar to the interfacial tension previously measured between coexisting nematic and isotropic DSCG phases (22), although nematic DSCG exists inside and outside the GUVs in our experiment. We return to this point in the following section.…”

Section: Resultssupporting

confidence: 86%

See 1 more Smart Citation

Straining soft colloids in aqueous nematic liquid crystals

Mushenheim

Pendery

Weibel

et al. 2016

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

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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.liquid crystals | soft colloids | vesicles | strain | elasticity T he majority of living materials are soft. This characteristic emerges from noncovalent interactions that lead to the formation of supramolecular structures that reorganize in response to subtle chemical and mechanical cues (1). The regulation of mechanical strain in particular and the engineering of responses to it across a hierarchy of spatial scales (from the molecular to the supramolecular to the cellular level) are increasingly understood to be one of the central sciences of living systems (2, 3).Inspired in part by the functionality of biological materials, a wide range of soft synthetic materials has been assembled by noncovalent interactions of molecular and macromolecular components (1, 4). In particular, liquid crystals (LCs) (Fig. 1A), which are phases that combine the molecular mobility of liquids with the long-range orientational ordering of crystalline solids, have provided the basis for a spectrum of responsive materials, including systems where electrical fields and mechanical strain compete to control electrooptical properties (5, 6). More recently, micro-and nanometer-sized colloidal particles dispersed in LCs have been used to form tunable self-assembled structures for photonic crystals and metamaterials (7). In the systems studied to date, however, the colloids have been "hard" compared with the LC, leading to mechanical straining of the LC but not the...

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Section: Resultssupporting

confidence: 86%

“…S12D). For reasons of brevity, we do not detail them here other than to note that neither the nematic DSCG inside highly elongated GUVs nor the nematic DSCG outside highly elongated GUVs showed evidence of the presence of twist, consistent with past observations of nematic tactoids with high aspect ratios (9,22,30).…”

Section: Inspection Ofsupporting

confidence: 69%

Straining soft colloids in aqueous nematic liquid crystals

Mushenheim

Pendery

Weibel

et al. 2016

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

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“…Here, we focus on the lyotropic droplets formed by an aqueous Ch suspension of cellulose nanocrystals (CNCs) and refer to this Ch phase as the Ch-CNC phase. Lyotropic Ch liquid crystals offer a different dimension of applications because (i) they are hydrophilic, in comparison with their hydrophobic thermotropic counterparts, and (ii) the micrometer size of the core of topological defects is significantly larger (24,25) than ∼10-nm core size in droplets of thermotropic liquid crystals (10). The implications of these features are in a potentially broader range of hydrophobicity/ hydrophilicity and sizes of additives templated by disclinations.…”

mentioning

confidence: 99%

Periodic assembly of nanoparticle arrays in disclinations of cholesteric liquid crystals

Prince

Cho

et al. 2017

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

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An important goal of the modern soft matter science is to discover new self-assembly modalities to precisely control the placement of small particles in space. Spatial inhomogeneity of liquid crystals offers the capability to organize colloids in certain regions such as the cores of the topological defects. Here we report two selfassembly modes of nanoparticles in linear defects-disclinations in a lyotropic colloidal cholesteric liquid crystal: a continuous helicoidal thread and a periodic array of discrete beads. The beads form one-dimensional arrays with a periodicity that matches half a pitch of the cholesteric phase. The periodic assembly is governed by the anisotropic surface tension and elasticity at the interface of beads with the liquid crystal. This mode of self-assembly of nanoparticles in disclinations expands our ability to use topological defects in liquid crystals as templates for the organization of nanocolloids. colloidal liquid crystals | nanoparticle self-assembly | liquid crystal droplets | topological defects | anisotropic surface tension T he most extensively studied liquid crystalline phase, the socalled nematic, has been so named after the linear defectdisclinations that appear as flexible threads in optical microscopy textures; "thread" is "ν«μα" in Greek (1, 2). The disclinations represent singularities of the director that describes the local orientation of molecules. As one approaches the "core" of the defect, director deformation becomes so strong that the degree of orientational order varies in space. Disclinations can attract additives, e.g., colloidal particles (3-8) and even small molecules (9, 10). Such an attraction is energetically favored, as the strongly distorted disclination core region is replaced with the additive (4). The unique templating ability of disclinations has stimulated the exploration of their applications, such as the fabrication of optical materials (11), conductive microwires (12), soft magnets (13), and electrooptical devices (5,14,15).Disclinations in nematic liquid crystals are generally onedimensional structures, as the director pattern repeats itself along the line. When an additive is attracted to the disclination core, two possible morphologies are expected: (i) continuous thread-like assembly, or (ii) a linear array of discrete beads. The disclination-templated assemblies reported so far had a threadlike shape, as observed for polymers in the so-called blue phases (15) and for molecular amphiphiles at the cores of nematic disclinations (9, 10).Here, we report the templating behavior of disclinations in the chiral version of the nematic liquid crystal, the so-called cholesteric (Ch) phase. The local directorn in this phase undergoes helicoid twisting around a helical axisv while being perpendicular to this axis (1, 2). Continuous twist leads to a pseudolayered structure, with a well-defined pitch but no modulation of density. Experiments were performed for spherical Ch droplets, in which disclinations correspond to the equilibrium state, thus ensuring...

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“…The shape of the negative tactoids is determined by a balance of the anisotropic surface tension and LC elasticity of the region outside the inclusions. [45] According to DSC investigations, the thermal behavior of fully aromatic PAME-V-PAME-VIII is similar to PAMEs with meta-azomethine phenyloxy units. A single T g value is found for PAME-V, whereas two glass transitions can be seen in DSC thermograms of PAME-VI, PAME-VII, and PAME-VIII (Table 2).…”

Section: Resultsmentioning

confidence: 98%

Synthesis and characterization of fluorinated poly(azomethine ether)s from new core-fluorinated azomethine-containing monomers

Kobzar

Ткаченко

Bliznyuk

et al. 2015

Designed Monomers and Polymers

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In this work, we describe the design and synthesis of novel core-fluorinated Schiff base monomers and conjugated polymers based on them. The new fully aromatic highly fluorinated poly(azomethine ether)s (PAMEs) were prepared by polycondensation of core-fluorinated azomethine-containing compounds. The structure of the monomers and polymers were confirmed by FTIR, F NMR spectroscopic analysis. The influence of synthesis condition on the properties of PAME compounds was investigated. Application of polarization microscopy with a temperature control thermal stage revealed thermotropic liquid crystalline (LC) behavior in the synthesized materials. Transition temperatures and a range of the existence of the LC phase were studied by a combination of the optical microscopy and DSC analysis. According to the TGA analysis, all the synthesized PAMEs show high thermal stability and thus offer a wide range of thermal processibility (up to 410-477 °C), which makes them prospective materials for many modern applications.

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Morphogenesis of defects and tactoids during isotropic–nematic phase transition in self-assembled lyotropic chromonic liquid crystals

Cited by 124 publications

References 88 publications

Straining soft colloids in aqueous nematic liquid crystals

Straining soft colloids in aqueous nematic liquid crystals

Periodic assembly of nanoparticle arrays in disclinations of cholesteric liquid crystals

Synthesis and characterization of fluorinated poly(azomethine ether)s from new core-fluorinated azomethine-containing monomers

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