Adsorption from polymer mixtures. The effect of molecular mass

Two approaches are used to study the adsorption of components from polydisperse polymer melts. The distribution of components of binary mixture of homopolymers differing only in molecular masses near the neutral wall is studied using the Scheujens-Fleer lattice model. An increase in the concentration of component with lower molecular mass near the wall observed under the considered conditions is caused by a decrease in the losses of configurational entropy of polymer chains. The adsorption of low-molecular-mass component is calculated for a large set of model parameters. The equation describing adsorption as a function of mixture concentration and parameter (N-1/N-2-1) characterizing the difference in chain lengths of N-1 and N-2 components is proposed. The proposed equation is a specific case of equation, which was derived using Flory-Huggins in in lattice theory and the data on the dependences of surface tension on the composition of polydisperse melts.