In:
The Journal of Chemical Physics, AIP Publishing, Vol. 138, No. 5 ( 2013-02-07)
Abstract:
A multiscale model for a colloid-polymer mixture is developed. The colloids are described as point particles interacting with each other and with the polymers with strongly repulsive potentials, while polymers interact with each other with a softer potential. The fluid in the suspension is taken into account by the multiparticle collision dynamics method (MPC). Considering a slit geometry where the suspension is confined between parallel repulsive walls, different possibilities for the hydrodynamic boundary conditions (b.c.) at the walls (slip versus stick) are treated. Quenching experiments are considered, where the system volume is suddenly reduced (keeping the density of the solvent fluid constant, while the colloid and polymer particle numbers are kept constant) and thus an initially homogeneous system is quenched deeply into the miscibility gap, where it is unstable. For various relative concentrations of colloids and polymers, the time evolution of the growing colloid-rich and polymer-rich domains are studied by molecular dynamics simulation, taking hydrodynamic effects mediated by the solvent into account via MPC. It is found that the domain size ℓd(t) grows with time t as ℓd(t) ∝ t1/3 for stick and (at late stages) as ℓd(t) ∝ t2/3 for slip b.c., while break-up of percolating structures can cause a transient “arrest” of growth. While these findings apply for films that are 5–10 colloid diameters wide, for ultrathin films (1.5 colloid diameters wide) a regime with ℓd(t) ∝ t1/2 is also identified for rather shallow quenches.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
2013
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
Permalink
