Confinement-induced screening of hydrodynamic interactions and spinodal decomposition: Multiscale simulations of colloid-polymer mixtures
1 Institut für Physik, Johannes Gutenberg-Universität - 55099 Mainz, Staudinger Weg 7, Germany
2 Theoretical Soft Matter and Biophysics, Institute for Advanced Simulation and Institute of Complex Systems, Forschungszentrum Jülich - 52425 Jülich, Germany
Received: 14 September 2012
Accepted: 5 November 2012
Phase separation kinetics of a colloid-polymer mixture confined between two planar repulsive walls is studied by a multiscale simulation approach. Colloids and polymers are described by particles interacting with continuous potentials suitable for molecular-dynamics simulation, while hydrodynamic interactions mediated by solvent particles are accounted for by the multiparticle collision dynamics method. Varying the distance D between the walls and the character of the boundary conditions, the interplay of structure formation parallel and perpendicular to the walls is studied, and the effect of hydrodynamics on the growth of domain size ℓd(t) with time t is elucidated. Only for slip boundary conditions a growth law ℓd(t)∝t2/3 is observed, but break-up of the percolating polymer-rich phase may “arrest” this growth. For stick boundary conditions hydrodynamic interactions are to a large extent screened and the diffusive Lifshitz-Slyozov growth law ℓd(t)∝t1/3 results.
PACS: 64.75.St – Phase separation and segregation in thin films / 64.75.-g – Phase equilibria / 64.75.Xc – Phase separation and segregation in colloidal systems
© EPLA, 2012