Random nematic structures in the absence of inherent frustrations

Abstract

We study the impact of anisotropic nanoparticles (NPs) on the nematic liquid crystal (LC) order. Within a mesoscopic Flory–Huggins-type approach we have estimated regimes where LC–NP mixtures are essentially homogenous. Using a lattice Lebwohl–Lasher type approach we have also studied the impact of anisotropic NPs on LC ordering. We analysed the cases where the orientations of NPs are either frozen-in or could be varied, to which we refer as random field mixtures and annealed mixtures, respectively. In the latter case we have demonstrated the existence of qualitatively different regimes. In particular, we determined the concentration regime, where LC configurations resembling a transparent nematic phase could be observed. Such domain patterns are stabilised by NPs hindering the annihilation of topological defects in LC order.

Keywords:

• liquid crystals
• defects
• random nematic structures
• surface phenomena

Acknowledgements

G.C. acknowledges the support of the Project PE3-1535 in the frame of the Action ‘Supporting Postdoctoral Researchers’ of the Operational Program ‘Education and Lifelong Learning’, co-financed by the European Social Fund and the Greek State. A.Z. and A.A. acknowledge the support of the Slovenian Research Agency Program P2-0348 ‘New Imaging and Analytical Methods’.