MONTE-CARLO STUDIES OF POLYMER INTERDIFFUSION AND SPINODAL DECOMPOSITION - A REVIEW

Putting a layer of polymer A on top of a layer of polymer B, the broadening of the interfacial profile is observed in the framework of a lattice model ('bond fluctuation method'). The interdiffusion constant is studied as a function of chain length, vacancy concentration, and interaction energy between unlike monomers, and a comparison with pertinent theoretical predictions is made. A lattice model where polymers are represented as self-avoiding walks on a simple cubic lattice is used to model 'spinodal decomposition', i.e. phase separation by 'uphill diffusion' in the unstable part of the phase diagram of a polymer mixture. For chain lengths N less-than-or-equal-to 32, the linearized Cahn-like theory describes the Monte Carlo results only qualitatively. A slowing down due to chain collapse is found for deep quenches and attractive interactions.