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 ξ_c 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 R_z radius of gyration varying as a power function of ξN^1/5: R_z(ξ)/R_z(0) ∼ (ξN^1/5)^ρ and ρ = -2ν/(1 - v). Meanwhile, (A-graft-B)_N macromolecules have much lower ξ_c and ξ_∞ values and thus are more prospective for practical applications.