Adsorption from a mixture of thermodynamically compatible polymers in dilute and semidilute solutions

Adsorption from solutions of a mixture of compatible polymers, namely, PC and poly-Ε-caprolactone, has been systematically investigated in a common solvent (chloroform) in the cross-over region. Isotherms are shown for adsorption from the individual solutions and from their mixtures in the concentration range up to and after the critical concentration for overlap of the polymeric coils. In order to explain the isotherms obtained, both for the binary system (polymer-solvent) and also for the ternary systems (polymer-polymer-solvent), values of the critical concentration and of the unperturbed macromolecular dimensions have been calculated and the dimensions of the polymer aggregates have been determined experimentally as a function of the regime of solution. The results of the present investigation are compared with those obtained previously for the incompatible system PS-PDMS. It is shown that the decisive influence on the adsorption of polymers in the case of compatible and of incompatible polymeric systems is the presence in the mixture of a second component that changes the thermodynamic quality of the polymeric solvent.