Macromolecules with amphiphilic monomer units at interface of two immiscible liquids.

The adsorption of macromolecules with amphiphilic monomer units at the liquid-liquid interface was studied. The amphiphilic structure of monomer units with groups selectively interacting with α and β liquids was described by the A-graft-B dumbbell model. The calculations were performed for the symmetrical interaction of A and B groups with liquids, different selectivity parameters ξ and degree of polymerization N. The simulations indicate a three-step adsorption scenario, including non-adsorbed, weak and strong localization states. It was shown that the adsorption of (A-graft-B)N macromolecules obeys scaling laws developed to describe the adsorption of the alternating (AB)N copolymer at the liquid-liquid interface with critical selectivity parameter ξc of transition into the weak localization state depending on the degree of polymerization as N-1/5; critical selectivity parameter ξ∞ of transition to the strong localization regime non-depending on the degree of polymerization; and relative change of perpendicular Rz radius of gyration varying as a power function of ξN1/5: Rz(ξ)/Rz(0) ∼ (ξN1/5)ρ and ρ = -2ν/(1 - v). Meanwhile, (A-graft-B)N macromolecules have much lower ξc and ξ∞ values and thus are more prospective for practical applications.