Universal amplitude ratios for the surface tension of polymer solutions

Abstract

Arguments are given that (semi-) dilute polymer solutions are promising candidates for probing multicritical surface behavior in a real system. Multicritical surface properties of the energy density in a semi-infinite n-component Ginzburg–Landau model are discussed and used to obtain results for the monomer density and surface tension near the threshold for polymer surface adsorption in a good solvent. Directly at threshold, the surface tension is found to decrease with increasing monomer concentration. For a quantitative comparison with experiments several universal amplitude ratios are calculated. These relate surface critical properties at the so-called ordinary, special (or surface bulk), and extraordinary transitions of the semi-infinite Ginzburg–Landau model.