Effects of A-B block copolymer additives on interfacial tension of A/B polymer blends near the critical temperature: Comparison of mean-field calculations with experiments

A simple square-gradient theory (SGT) for the interfacial tension of homopolymer-A/homopolymer-B blends with A-B diblock copolymer additives near the critical solution temperature, T_c, has been proposed to describe the experimental finding that, as the temperature changes away from T_c, the interfacial tension γ increases, and then decreases, exhibiting a maximum. Dynamic mean-field calculations (DMF) of a self-consistent field treatment are also performed to describe it and are compared with those of the proposed SGT. Both of SGT and DMF reasonably describe the γ-maximum behavior and the additive-concentration dependence of the location of γ-maximum in γ-T relation. Agreements of SGT with DMF results are quite satisfactory, although SGT, in general, gives thinner adsorbed layers of block copolymers than those evaluated by DMF.