Mesoscale structures at complex fluid–fluid interfaces: a novel lattice Boltzmann/molecular dynamics coupling

Abstract

Complex fluid–fluid interfaces featuring mesoscale structures with adsorbed particles are key components of newly designed materials which are continuously enriching the field of soft matter. Simulation tools which are able to cope with the different scales characterizing these systems are fundamental requirements for efficient theoretical investigations. In this paper we present a novel simulation method, based on the approach of Ahlrichs and Dünweg [Ahlrichs and Dünweg, Int. J. Mod. Phys. C, 1998, 9, 1429], that couples the “Shan–Chen” multicomponent lattice Boltzmann technique with off-lattice molecular dynamics to simulate efficiently complex fluid–fluid interfaces. We demonstrate how this approach can be used to study a wide class of challenging problems. Several examples are given, with an accent on bicontinuous phase formation in polyelectrolyte solutions and ferrofluid emulsions. We also show that the introduction of solvation free energies in the particle–fluid interaction unveils the hidden, multiscale nature of the particle–fluid coupling, allowing us to treat symmetrically (and interchangeably) the on-lattice and off-lattice components of the system.