The competition between additives for a place in the polymer matrix are discovered when the blending components ensure the enthalpy of mixing to be nearly zero. The competition of the additives exists as the process of accelerated exudation of one another from glasslike or jellylike films. This is inconsistent with the entropic nature of the mixtures assumed for the homogeneous polymer solutions. The considered effects are beyond the statistical thermodynamics of solutions, and they are explained by the specificity of the chain-sponge organization of a noncrystalline polymer matrix. The equilibrium sorption of volatile compounds by polymer samples is explained by the mechanism of structural entropic solvation and is described by the equation of the micropore volume filling theory.