Polyhedral liquid droplets: Recent advances in elucidation and application

Marin, Orlando; Tkachev, Maria; Sloutskin, Eli; Deutsch, Moshe

doi:10.1016/j.cocis.2020.05.006

Cited by 14 publications

(22 citation statements)

References 60 publications

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“…S7 ). A similar balance of positive and negative surface-scaling energy terms was also suggested to stabilize the self-shaping of oil droplets ( 3 , 46 ), albeit this mechanism does not seem to be supported by some of the recent experimental evidence ( 47 , 48 ). Note that this phenomenological inference does not reveal the microscopic origin of such behavior, which encompasses the effects of both surfactants and their distributions in the dispersed (LC) and continuous (water) phase, respectively.…”

Section: Discussionmentioning

confidence: 97%

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: 97%

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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“…Whereas these fascinating experimental results are now well reproducible (see Ref. [7] for a recent overview), a convincing explanation of the physical mechanisms underpinning the sequence of shape transformations is still lacking, despite two alternative scenarios having been proposed [2][3][4][5][6][8][9][10][11][12]. The first of these, hereafter referred to as rotator phase mechanism [2,10], revolves around the existence of ≈ 300 nm-thick rotator phase in the proximity of the droplet's surface, serving as a plastic scaffold for the observed shape transformations, especially across different flat morphologies [10].…”

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confidence: 84%

“…In particular, we highlighted the importance of the spontaneous curvature of the interface monolayer, that, by effectively hindering the magnitude of capillary forces, allows one to reproduce the counterintuitive sizedependence observed in the experiments. While more advanced theoretical models may be needed to describe the behavior of multicomponent droplets [7], we antici-pate our present work to provide the bases for these more complex future models.…”

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confidence: 99%

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Faceting and Flattening of Emulsion Droplets: A Mechanical Model

et al. 2021

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“…In common experience, a droplet minimizing its surface area adopts a perfectly spherical shape. While emulsion droplets usually conform to this expectation, at low temperatures, the surface tension can vanish and effects from a hexatically ordered interfacial layer dominate, inducing polyhedral droplets [2,3]. Factors such as a negative surface tension and gravity [4] induce further exotic droplet morphologies such as flattened polygons, rods, and protrusions.…”

Section: Introductionmentioning

confidence: 98%

Effects of orientational order on modulated cylindrical interfaces

2022

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Cylindrical interfaces occur in sheared or deformed emulsions and as biological or technological lipid monolayer or bilayer tubules. Like the corresponding spherical droplets and vesicles, these cylinder-like surfaces may host orientaional order with n-fold rotational symmetry, for example in the positions of lipid molecules or of spherical nanoparticles. We examine how that order interacts with and induces shape modulations of cylindrical interfaces. While on spherical droplets 2n topological defects necessarily exist and can induce icosahedral droplet shapes, the cylindrical topology is compatible with a defect-free patterning. Nevertheless, once a modulation is introduced by a mechanism such as spontaneous curvature, nontrivial patterns of order, including ones with excess defects, emerge and have nonlinear effects on the shape of the tube. Examining the equilibrium energetics of the system analytically and with a lattice-based Markov chain Monte Carlo simulation, we predict low-temperature morphologies of modulated cylindrical interfaces hosting orientational order. A shape modulation induces a banded pattern of alternatingly isotropic and ordered interfacial material. Furthermore cylindrical systems can be divided into Type I, without defects, and Type II, which go through a spectrum of defect states with up to 4n excess defects.The character of the curvature-induced shape transition from unmodulated to modulated cylinders is continuous or discontinuous accordingly.

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Polyhedral liquid droplets: Recent advances in elucidation and application

Cited by 14 publications

References 60 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

Faceting and Flattening of Emulsion Droplets: A Mechanical Model

Effects of orientational order on modulated cylindrical interfaces

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