Homopolymer Physisorption: A Monte Carlo Study

Abstract

We present a systematic comparison between predictions of the complete lattice mean field theory and configurational bias lattice Monte Carlo simulations of homopolymers adsorbed on solid surfaces from solution. The focus is on moderate chain lengths typical of colloid stabilizers. These chains are too short to follow asymptotic power law behavior, especially at low bulk concentrations. Monte Carlo and lattice mean field results are qualitatively similar. However, mean field predictions on polymer volume fraction profiles are substantially lower than Monte Carlo data. The discrepancy is more pronounced for dilute bulk volume fractions and long chains. The various measures of adsorbed layer thickness reflect the underlying difference in the volume fraction profiles. The tail root-mean-square thickness, in particular, exhibits qualitatively different behavior. These findings underscore the necessity for further development of complete theories that go beyond mean field and microscopic approaches that link segmental and chain scales in nonhomogenenous environments.