The influence of nanoparticles on the phase and structural ordering for nematic liquid crystals

• Published in: Journal of physics. Condensed matter 2008-06, Vol.20 (24), p.244112-244112 (7)
• Main Authors: Kralj, S, Bradač, Z, Popa-Nita, V
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Liquid crystals; Physics; Specific phase transitions; Structure of solids and liquids; crystallography; Transitions in liquid crystals
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/20/24/244112

We study the influence of nanoparticles (NPs) on liquid crystal (LC) ordering. As regards the structural ordering we consider NPs as a source of a quenched random field. Roughly such a situation is encountered in mixtures of LCs and aerosil NPs (aerosil NPs are spherular ones). Using the semi-microscopic lattice model and Brownian molecular simulation we show that after a quench from the isotropic phase a quasi-stable domain pattern forms. The characteristic size of an average domain is inversely proportional to the concentration of NPs, and domain patterns exhibit memory effects. In the study of the phase behaviour we limit consideration to NPs resembling LC molecules. A Landau-type free energy expression is derived for the mixture, originating from the Maier-Saupe molecular approach. We show that the resulting phase behaviour exhibits the slave-master behaviour as the temperature or pressure is varied.