Pattern Formation of Two-Dimensional Smectic-A Filaments

Todorokihara, Masayoshi; K, Seike; Naito, Hiroyoshi; Ouyang, Zhen

doi:10.1080/10587250108025009

Cited by 4 publications

(6 citation statements)

References 10 publications

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“…Unlike in the smectic phase, in which the mechanics of fiber growth is rather complex [described in detail by Palffy-Muhoray ( 49 ); see also refs. 33 and 50 ], the fiber formation in N LCs is a result of the balance between the surface- and bulk-energy contributions. Therefore, N fiber growth allows us to draw simple qualitative relations between the equilibrium fiber state and the material parameters.…”

Section: Discussionmentioning

confidence: 99%

Self-shaping liquid crystal droplets by balancing bulk elasticity and interfacial tension

Peddireddy

Čopar

et al. 2021

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

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The shape diversity and controlled reconfigurability of closed surfaces and filamentous structures, universally found in cellular colonies and living tissues, are challenging to reproduce. Here, we demonstrate a method for the self-shaping of liquid crystal (LC) droplets into anisotropic and three-dimensional superstructures, such as LC fibers, LC helices, and differently shaped LC vesicles. The method is based on two surfactants: one dissolved in the LC dispersed phase and the other in the aqueous continuous phase. We use thermal stimuli to tune the bulk LC elasticity and interfacial energy, thereby transforming an emulsion of polydispersed, spherical nematic droplets into numerous, uniform-diameter fibers with multiple branches and vice versa. Furthermore, when the nematic LC is cooled to the smectic-A LC phase, we produce monodispersed microdroplets with a tunable diameter dictated by the cooling rate. Utilizing this temperature-controlled self-shaping of LCs, we demonstrate life-like smectic LC vesicle structures analogous to the biomembranes in living systems. Our experimental findings are supported by a theoretical model of equilibrium interface shapes. The shape transformation is induced by negative interfacial energy, which promotes a spontaneous increase of the interfacial area at a fixed LC volume. The method was successfully applied to many different LC materials and phases, demonstrating a universal mechanism for shape transformation in complex fluids.

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Section: Discussionmentioning

confidence: 99%

Self-shaping liquid crystal droplets by balancing bulk elasticity and interfacial tension

Peddireddy

Čopar

et al. 2021

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

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“…The filament elasticity is defined by its tension and bending moduli. External fields modifying the filament curvature include magnetic, electric, and flow fields [16][17][18]. This brief communication focuses on the formation of smectic A filaments from an isotropic * Corresponding author.…”

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confidence: 99%

“…In summary, a simple flow perturbation model of the evolution of buckling instabilities observed during filament growth by smectic A phase ordering [15,18,19] was developed. Using a preaveraging approximation, the linearized shape equation is put into the format of a flow-modified Cahn-Hilliard equation.…”

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confidence: 99%

“…In this case a thermal quench produces a filament that buckles with a wave-vector, q, that can be tuned by an externally imposed electric field [18]. In the absence of external fields, the evolution of the buckling instability satisfies the Cahn-Hilliard equation [1] and is given by [20]:…”

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confidence: 99%

“…Filaments, fibers, ropes, and strings are essentially 1D objects and are equally important in technological and biological systems [1,5]. The growth of 1D structures leads to straight, helical, and random geometries [11][12][13][14][15] which depend on the growth process, the filament elasticity, and the presence of external fields [16][17][18]. Growth processes include polymerization, accretion, diffusional phase transitions, and phase ordering (diffusionless phase transition) [1][2][3][4][5].…”

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confidence: 99%

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Flow perturbation model for filament buckling

Rey

Abukhdeir

2008

Journal of Non-Newtonian Fluid Mechanics

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Thermodynamics, Transition Dynamics, and Texturing in Polymer-Dispersed Liquid Crystals with Mesogens Exhibiting a Direct Isotropic/Smectic-A Transition

2009

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Experimental and modeling/simulation studies of phase equilibrium and growth morphologies of novel polymer-dispersed liquid crystal (PDLC) mixtures of PS (polystyrene) and liquid crystals that exhibit a direct isotropic/smectic-A (lamellar) mesophase transition were performed for PS/10CB (decylcyanobiphenyl) and PS/12CB (dodecyl-cyanobiphenyl). Partial phase diagrams were determined using polarized optical microscopy (POM) and differential scanning calorimetry (DSC) for different compositions of both materials, determining both phase separation (liquid/liquid demixing) and phase ordering (isotropic/smectic-A transition) temperatures. The Flory-Huggins theory of isotropic mixing and Maier-Saupe-McMillan theory for smectic-A liquid crystalline ordering were used to computationally determine phase diagrams for both systems, showing good agreement with the experimental results. In addition to thermodynamic observations, growth morphology relations were found depending on phase transition sequence, quench rate, and material composition. Three stages of liquid crystal-rich domain growth morphology were observed: spherical macroscale domain growth ("stage I"), highly anisotropic domain growth ("stage II"), and sub-micron spheroid domain growth ("stage III"). Nano-scale structure of spheroidal and spherocylindrical morphologies were then determined via two-dimensional simulation of a high-order Landau-de Gennes model. Morphologies observed during stage II growth are typical of direct isotropic/smectic-A phase transitions, such as highly anisotropic "batonnets" and filaments. These morphologies, which are found to be persistent in direct isotropic/smectic-A PDLCs, could provide new functionality and applications for these functional materials.

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Pattern Formation of Two-Dimensional Smectic-A Filaments

Cited by 4 publications

References 10 publications

Self-shaping liquid crystal droplets by balancing bulk elasticity and interfacial tension

Self-shaping liquid crystal droplets by balancing bulk elasticity and interfacial tension

Flow perturbation model for filament buckling

Thermodynamics, Transition Dynamics, and Texturing in Polymer-Dispersed Liquid Crystals with Mesogens Exhibiting a Direct Isotropic/Smectic-A Transition

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