Magnetically responsive gourd-shaped colloidal particles in cholesteric liquid crystals

Abstract

Particle shape and medium chirality are two key features recently used to control anisotropic colloidal self-assembly and dynamics in liquid crystals. Here, we study magnetically responsive gourd-shaped colloidal particles dispersed in cholesteric liquid crystals with periodicity comparable or smaller than the particle's dimensions. Using magnetic manipulation and optical tweezers, which allow one to position colloids near the confining walls, we measured the elastic repulsive interactions of these particles with confining surfaces and found that separation-dependent particle-wall interaction force is a non-monotonic function of separation and shows oscillatory behavior. We show that gourd-shaped particles in cholesterics reside not on a single sedimentation level, but on multiple long-lived metastable levels separated by a distance comparable to cholesteric periodicity. Finally, we demonstrate three-dimensional laser tweezers assisted assembly of gourd-shaped particles taking advantage of both orientational order and twist periodicity of cholesterics, potentially allowing new forms of orientationally and positionally ordered colloidal organization in these media.

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Cited by in corpus (6)

• Liquid Crystal Colloids
• Hexadecapolar colloids
• Edge pinning and transformation of defect lines induced by faceted colloidal rings in nematic liquid crystals
• Self-assembly of colloidal particles in deformation landscapes of electrically driven layer undulations in cholesteric liquid crystals
• Colloidal spirals in nematic liquid crystals
• Repulsion-attraction switching of nematic colloids formed by liquid crystal dispersions of polygonal prisms