Polydispersity Effect on the Adsorption of Polymer Mixtures

The changes in molecular mass distribution (MMD) after adsorption from solution in concentration regions below and above the critical concentration of overlapping have been studied for various polymers and their mixtures. It was found that the formation of entanglements in both binary and ternary solutions affects the changes in MMD. For binary and ternary solutions above the critical concentration of overlapping, C*, the entanglements lead to diminishing selectivity of adsorption of high-molecular-weight fractions. Simultaneously, transition through C* diminishes adsorption of the fractions of higher surface activity. It may be assumed that the entanglements play the role of an additional energetic barrier which macromolecules must overcome to be adsorbed. The transition through the critical concentration of overlapping for the case of binary solutions diminishes the selectivity of adsorption of high molecular fractions. Adsorption of polar polymers from the ternary solutions both below and above C* leads to the appearance of the bimodality of MMD due to adsorption of surface-active fractions. Copyright 2000 Academic Press.