Abstract
Copolymers are commonly used as interface modifiers that allow for the compatibilization of polymer
components in a blend. For copolymers to function as a compatibilizer, they must diffuse through the
matrix of the blend to the interface between the two blend components. The diffusivity of a copolymer
in a blend matrix therefore becomes important in determining good candidates for use as compatibilizers.
In this work, coarse-grained Monte Carlo simulations using the bond fluctuation model modified
with an overlap penalty have been developed to study the diffusive behavior of PS/PMMA random
copolymers in a PMMA homopolymer blend. The simulations vary the connectivity between different
monomers, the thermodynamic interactions between the monomers which manifest within a chain,
and between copolymer and homopolymer matrix and define the monomer friction coefficient of each
component independently, allowing for the determination of the combined effect of these parameters
on copolymer chain diffusion. The results of this work indicate that PS-r-PMMA copolymer diffusion
is not linearly dependent on the copolymer composition on a logarithmic scale, but its diffusion is a
balance of the kinetics governed by the dominant motion of the faster styrene monomers and thermodynamics, which are governed by the concentration of styrene monomer within a given monomer’s
local volume.
