An investigation of the stable orientations of orthorhombic particles in a thin film and their effect on its critical failure pressure

Morris, G.; Neethling, S.J.; Cilliers, J.J.

doi:10.1016/j.jcis.2011.05.061

Cited by 24 publications

(20 citation statements)

References 17 publications

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“…1(d)]. Similar predictions have also been made for cubes adsorbed at thin films [48]. To study N cubes in such a configuration, we first consider, in Fig.…”

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confidence: 59%

Self-Assembly of Cubes into 2D Hexagonal and Honeycomb Lattices by Hexapolar Capillary Interactions

2016

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Particles adsorbed at a fluid-fluid interface induce capillary deformations that determine their orientations and generate mutual capillary interactions which drive them to assemble into 2D ordered structures. We numerically calculate, by energy minimization, the capillary deformations induced by adsorbed cubes for various Young's contact angles. First, we show that capillarity is crucial not only for quantitative, but also for qualitative predictions of equilibrium configurations of a single cube. For a Young's contact angle close to 90°, we show that a single-adsorbed cube generates a hexapolar interface deformation with three rises and three depressions. Thanks to the threefold symmetry of this hexapole, strongly directional capillary interactions drive the cubes to self-assemble into hexagonal or graphenelike honeycomb lattices. By a simple free-energy model, we predict a density-temperature phase diagram in which both the honeycomb and hexagonal lattice phases are present as stable states. DOI: 10.1103/PhysRevLett.116.258001 Over a century ago, it had already been observed that submm sized particles strongly adsorb at fluid-fluid interfaces [1,2]. Indeed, a fluid-fluid interface of area A and surface tension γ has a free energy cost γA, and particles can reduce A by adsorbing at the interface. The bonding potential is usually strong enough to allow stable monolayers of particles. Since a pioneering study by Pieranski [3], a lot of interest has been devoted to these quasi-2D systems, which have many applications, e.g., emulsions [4][5][6][7][8][9], coatings [10,11], optics [12], and new material development [13]. Because of the contact angle constraint imposed by Young's Law, an adsorbed particle in general induces deformations in the shape of the fluid-fluid interface. These so-called capillary deformations are responsible for capillary interactions between the adsorbed particles [14,15], which regulate the particle self-assembly at the interface [16][17][18]. These interactions can be tuned by varying, e.g., the particle shape and chemistry [10,[19][20][21], or the curvature of the fluidfluid interface [22][23][24]. Very recent experiments [25][26][27] have shown that adsorbed nanocubes with truncated corners can assemble into graphenelike honeycomb and hexagonal lattices. The origin of these structures is unknown, although ligand adsorption and van der Waals forces between specific facets of the truncated cubes have been suggested [25]. In this Letter, however, we show that generic cubes with homogeneous surface properties generate hexapolar capillary deformations which are largely responsible for the observed structures. Cubes of other materials or dimensions could, therefore, form similar structures.A primary step for understanding adsorbedparticle systems is the study of an isolated particle at a macroscopically flat fluid-fluid interface. Important issues are the equilibrium configuration of the particle at the interface [28][29][30][31] and the adsorption energy [32-34] which depend on the particl...

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“…1(d)]. Similar predictions have also been made for cubes adsorbed at thin films [48]. To study N cubes in such a configuration, we first consider, in Fig.…”

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confidence: 59%

Self-Assembly of Cubes into 2D Hexagonal and Honeycomb Lattices by Hexapolar Capillary Interactions

2016

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“…26,27 It is known that single cubes with specific surface wettability possess a preferred orientation. 20,21,28 Thus, presumably cubes possess a preferred orientation at the aqueous subphase/air interface for a specific surface tension. However, the energy barriers between the states of preferred orientation and other orientations, which are still unknown so far, are different for subphases with different surface tensions.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Reconfigurable Microcube Assemblies at the Liquid/Air Interface: The Impact of Surface Tension on Orientation and Capillary-Force-Interaction-Driven Assembly

2019

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The systematic investigation of the dependence of the orientation and capillary interaction of hydrophobized polystyrene microcubes at the liquid/air interface on the surface tension of the aqueous subphase is reported. By decreasing the subphase surface tension, the preferential orientation of the cubes was observed to change independent of the surfactant type from the vertex up to the edge up and finally to the face up. Concomitantly, the structure of the aggregates obtained by cube assembly was observed to change from a close-packed hexagonal to tilted linear and finally to flat plate. In particular, the preferential orientation of the cubes was virtually independent of the surfactant charge at a constant surface tension. In addition, reconfigurable microcube assemblies at the liquid/air interface, which respond to the surface tension of the subphase, were observed for the first time. The dynamic reconfigurability of preformed microcube aggregates induced by adding surfactant to the subphase may open new pathways to dynamic assemblies at liquid/air interfaces, which may be interesting, e.g., for sensing applications.

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“…The equilibrium shape of a gas-liquid interface can be found iteratively by minimising the total potential energy, which is the sum of the surface free energy and the gravitational energy, when a particle is attached to a bubble. Recently Surface Evolver software has been used to investigate the behaviour of orthorhombic particles at the gas-liquid interface (Morris et al, 2011a(Morris et al, , 2011b. In the present study, Surface Evolver has been used to find the equilibrium shape of the gas-liquid interface and to calculate the capillary force of attachment between a bubble and non-axisymmetric particles in several geometries.…”

Section: Methods Of Solution Using Surface Evolvermentioning

confidence: 99%

The capillary force between a bubble and a cubical particle

Gautam

Jameson

2012

Minerals Engineering

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An investigation of the stable orientations of orthorhombic particles in a thin film and their effect on its critical failure pressure

Cited by 24 publications

References 17 publications

Self-Assembly of Cubes into 2D Hexagonal and Honeycomb Lattices by Hexapolar Capillary Interactions

Self-Assembly of Cubes into 2D Hexagonal and Honeycomb Lattices by Hexapolar Capillary Interactions

Reconfigurable Microcube Assemblies at the Liquid/Air Interface: The Impact of Surface Tension on Orientation and Capillary-Force-Interaction-Driven Assembly

The capillary force between a bubble and a cubical particle

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