Induced anticlinic ordering and nanophase segregation of bow-shaped molecules in a smectic solvent

Abstract

Recent experiments indicate that doping low concentrations of bent-core molecules into calamitic smectic solvents can induce anticlinic and biaxial smectic phases. We have carried out Monte Carlo simulations of mixtures of rodlike molecules (hard spherocylinders with length/breadth ratio L_rod/D=5) and bow-shaped molecules (hard spherocylinder dimers with length/breadth ratio L_ban/D=5 or 2.5 and opening angle ψ). We find that a low concentration (3%) of L_ban/D=5 dimers induces anticlinic ( SmC_A) ordering in an untilted smectic (SmA) phase for 100°≤ψ<150°. For L_ban/D=2.5, no tilted phases are induced. However, with decreasing ψ we observe a sharp transition from intralamellar nanophase segregation (bow-shaped molecules segregated within smectic layers) to interlamellar nanophase segregation (bow-shaped molecules concentrated between smectic layers) near ψ=130°.