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RESEARCH PRODUCT

Confinement-induced screening of hydrodynamic interactions and spinodal decomposition: Multiscale simulations of colloid-polymer mixtures

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description

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.