Influence of polymer structure on adsorption behavior at solid–liquid interface by Monte Carlo simulation

Abstract

Monte Carlo simulations for the adsorption of polymers including random copolymer, homopolymer, diblock copolymer and two kinds of triblock copolymers, respectively, in nonselective solvent at solid–liquid interface have been performed on a simple lattice model. The effect of polymer structure on adsorption properties was examined. In simulations, all polymeric molecules are modeled as self-avoiding linear chains composed of two segments A and B while A is attractive to the surface and B is non-attractive. It was found that for all polymers, the size distribution of various configurations is determined by the linked sequence of segments and the interaction energy between segment and surface. The results of simulation show that the adsorbed amount always increases with increasing bulk concentration but the adsorption layer thickness is mostly dependent on the adsorption energy at a fixed fraction of segments A. On the other hand, diblock copolymer has always the highest surface coverage and adsorbed amount, while random copolymers and homopolymers give generally the smallest surface coverage and adsorbed amount. It is shown that the sequence of polymer chains, i.e. molecular structure, is the most important factor in affecting adsorption properties at the same composition and interaction between segment and surface. The results also show that the adsorption behavior of random copolymers is remarkably different from that of block copolymers, but acting like homopolymer.