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

Author： Winkler A. Virnau P. Binder K. Winkler R. G. Gompper G.

Publisher： Edp Sciences

E-ISSN： 1286-4854|100|4|46003-46003

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.100, Iss.4, 2012-11, pp. : 46003-46003

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Abstract

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 ℓ_d(t) with time t is elucidated. Only for slip boundary conditions a growth law ℓ_d(t)∝t^2/3 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 ℓ_d(t)∝t^1/3 results.