Equilibrium state of a cylindrical particle with flat ends in nematic liquid crystals

Hashemi, S. M ; Sharif University of Technology | 2015

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  1. Type of Document: Article
  2. DOI: 10.1103/PhysRevE.91.012503
  3. Publisher: American Physical Society , 2015
  4. Abstract:
  5. A continuum theory is employed to numerically study the equilibrium orientation and defect structures of a circular cylindrical particle with flat ends under a homeotropic anchoring condition in a uniform nematic medium. Different aspect ratios of this colloidal geometry from thin discotic to long rodlike shapes and several colloidal length scales ranging from mesoscale to nanoscale are investigated. We show that the equilibrium state of this colloidal geometry is sensitive to the two geometrical parameters: aspect ratio and length scale of the particle. For a large enough mesoscopic particle, there is a specific asymptotic equilibrium angle associated to each aspect ratio. Upon reducing the particle size to nanoscale, the equilibrium angle follows a descending or ascending trend in such a way that the equilibrium angle of a particle with the aspect ratio bigger than 1:1 (a discotic particle) goes to a parallel alignment with respect to the far-field nematic, whereas the equilibrium angle for a particle with the aspect ratio 1:1 and smaller (a rodlike particle) tends toward a perpendicular alignment to the uniform nematic direction. The discrepancy between the equilibrium angles of the mesoscopic and nanoscopic particles originates from the significant differences between their defect structures. The possible defect structures related to mesoscopic and nanoscopic colloidal particles of this geometry are also introduced
  6. Keywords:
  7. Aspect ratio ; Continuum mechanics ; Defect structures ; Defects ; Geometry ; Liquid crystals ; Nanotechnology ; Particle size ; Superconducting materials ; Asymptotic equilibrium ; Colloidal particle ; Cylindrical particles ; Equilibrium orientations ; Homeotropic anchoring ; Mesoscopic particles ; Parallel alignments ; Rod-like particles ; Nematic liquid crystals
  8. Source: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 91, Issue 1 , January , 2015 ; 15393755 (ISSN)
  9. URL: http://journals.aps.org/pre/abstract/10.1103/PhysRevE.91.012503