Phase equilibrium and structure formation in gold nanoparticles—nematic liquid crystal composites: experiments and theory

Abstract

A theoretical and experimental study of mixtures of a calamitic nematic liquid crystal and gold nanoparticles capped with mixed monolayers (alkylic + mesogenic ligands) is presented. The effect of the ligand monolayer composition and nanoparticle concentration on the solubility in the isotropic phase and on the isotropic–nematic phase transition is studied. Mixed monolayers show the highest miscibility and lead to the formation of well-defined cellular networks. This behaviour is explained in terms of a mean-field thermodynamic model, in combination with a phenomenological expression for the isotropic interaction parameter that accounts for entropic and enthalpic effects of the mixed ligand monolayer. The final structure of the material is shown to be determined essentially by the phase equilibrium behaviour.