Molecular dynamics simulation study of spherical nanoparticles in a nematogenic matrix: Anchoring, interactions, and phase behavior

Jianqing Xu, Dmitry Bedrov, Grant D. Smith, and Matthew A. Glaser

Phys. Rev. E 79, 011704 – Published 14 January 2009

Abstract

Molecular dynamics simulations of spherical nanoparticles (NPs) in a nematogenic matrix of soft spherocylinders (SSCs) with equal NP diameter and SSC length were performed. The NPs were found to be dispersed in the isotropic SSC matrix. At higher pressure, the NP-SSC mixture demixed into a NP-poor nematic phase and a NP-rich isotropic phase over most of the composition range investigated. However, at low NP concentrations a single-phase nematic with dispersed NPs was observed, while at very high NP concentration no nematic phase was observed. When the NP-SSC interactions were changed to promote homeotropic anchoring, the matrix-induced interaction between NPs in the isotropic SSC matrix exhibited strong intermediate-range repulsion that was expected to result in even greater dispersion of NPs. However, many-body effects appear to dominate NP-NP interactions in the isotropic SSC matrix with homeotropic anchoring even at the lowest NP concentration investigated, resulting in suppression of the intermediate range repulsion leading to aggregation of the NPs.