Colloids in confined liquid crystals: a plot twist in the lock-and-key mechanism

Boniello, Giuseppe; Luo, Yimin; Beller, Daniel A.; Serra, Francesca; Stebe, Kathleen J.

doi:10.1039/c9sm00788a

Cited by 5 publications

(7 citation statements)

References 49 publications

(51 reference statements)

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“…In conclusion, it is our hope that this work might inspire new investigations into colloidal systems that exploit the elastic energy landscapes in confined liquid crystals. The deliberate development and exploitation of fully three-dimensional director fields (e.g., with cholesteric liquid crystals) is the focus of a separate study by our group . When combined with external fields, stimuli to reconfigure liquid crystals, or reconfigurable boundaries, the interactions explored here provide a basis for reconfigurable structures.…”

Section: Discussionmentioning

confidence: 99%

“…The deliberate development and exploitation of fully three-dimensional director fields (e.g., with cholesteric liquid crystals) is the focus of a separate study by our group. 37 When combined with external fields, stimuli to reconfigure liquid crystals, or reconfigurable boundaries, the interactions explored here provide a basis for reconfigurable structures.…”

Section: ■ Conclusionmentioning

confidence: 99%

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Deck the Walls with Anisotropic Colloids in Nematic Liquid Crystals

et al. 2019

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The ability to dictate colloid motion is an important challenge in fields ranging from materials science to living systems. Here, by embedding energy landscapes in confined nematic liquid crystals, we design a versatile platform to define colloidal migration. This is achieved by placing a wavy wall, with alternating hills and wells, in nematic liquid crystals, to impose a smooth elastic energy field with alternating splay and bend distortions. This domain generates (meta) stable loci that act as attractors and unstable loci that repel colloids over distances large compared to the colloid radius. Energy gradients in the vicinity of these loci are exploited to dictate colloid trajectories. We demonstrate several aspects of this control, by studying transitions between defect configurations, propelling particles along well defined paths and exploiting multistable systems to send particles to particular sites within the domain. Such tailored landscapes have promise in reconfigurable systems and in microrobotics applications.

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Section: Discussionmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

Deck the Walls with Anisotropic Colloids in Nematic Liquid Crystals

et al. 2019

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“…These defects are point singularities in the director field, which are computationally burdensome; however, the inclusion of S allows these singularities to locally melt in a finite defect core, making them more amenable to computational approaches. For this reason, Q-theory is used extensively in numerical simulations nematics, including colloidal liquid crystals [63][64][65][66], living liquid cyrstals [67,68] and active liquid crystals [69][70][71][72][73].…”

Section: I2 Q-tensor Landau-de Gennes Theory Of Nematicsmentioning

confidence: 99%

“…High b ⊥ 1 prohibits twist deformations and b 1 can be increased to prohibit bend of the layer normal. Splay deformations proportional to ∇ • N do not appear in equation (64) and so splay deformations of the layer normal induce no free energy cost in the incompressible limit-these only arise at higher order from f curv .…”

Section: Elastic De Gennes-mcmillan Theorymentioning

confidence: 99%

Smectic layering: Landau theory for a complex-tensor order parameter

Paget

Alberti

Mazza

et al. 2022

J. Phys. A: Math. Theor.

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Composed of microscopic layers that stack along one direction while maintaining fluid-like positional disorder within layers, smectics are excellent systems for exploring topology, defects and geometric memory in complex confining geometries. However, the coexistence of crystalline-like characteristics in one direction and fluid-like disorder within layers makes lamellar liquid crystals notoriously difficult to model—especially in the presence of defects and large distortions. Nematic properties of smectics can be comprehensively described by the Q-tensor but to capture the features of the smectic layering alone, we develop a phenomenological Landau theory for a complex-tensor order parameter E, which is capable of describing the local degree of lamellar ordering, layer displacement, and orientation of the layers. This theory can account for both parallel and perpendicular elastic contributions. In addition to resolving the potential ambiguities inherent to complex scalar order parameter models, this model reduces to previous employed models of simple smectics, and opens new possibilities for numerical studies on smectics possessing many defects, within complex geometries and under extreme confinement.

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“…This approach includes colloidal diffusion, nemato-elasticity and hydrodynamics within complex boundaries. Inspired by experimental studies in which docking sites are of comparable size to colloids, 32,33,35 we focus on the effect of the amplitude of the wavy boundaries on the colloidal trajectories and velocities, for different anchoring conditions, and demonstrate that these systems have the potential to trap colloids at given points or allow colloidal conveyance. For intermediate amplitudes, elution follows stick-slip dynamics, with the ''sticking'' duration increasing with amplitude until the colloid locks in place.…”

Section: Introductionmentioning

confidence: 99%