Wetting transitions in polymer blends: Comparison between simulation and theory

Abstract

We investigate the problem of wetting transitions in polymer blends near a hard surface or wall by using a Monte Carlo technique to study the wetting transition along a path of increasing surface chemical potential. We introduce a parameter εs which describes the monomer-monomer interactions in the layer adjacent to the wall. This parameter is shown to behave similarly to the parameter g, used in mean field theory to describe the change in monomer-monomer interactions due to the wall. We identify a wetting tricritical point which may be denned either with respect to εs or the bulk density. For bulk densities less than the tricritical bulk density we obtain first-order transitions while for bulk densities greater than the tricritical bulk density we obtain critical wetting transitions, in accordance with mean-field theory. We also show how the molecular weight of the polymer can be varied to obtain first-order or critical wetting, as desired. © 1996 American Institute of Physics.