Two sets of terpolymers, polymer A and polymer B consisting of almost same level of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) component at 0.635 +/- 0.005 m and varying dodecyl methacrylate (DoDMAc) and monomethoxy poly(ethylene glycol) acrylate (PEGAc) components have been designed. Polymer A, consisting of less C-12 component, has been shown to promote intermolecular aggregated structures wherein C-12 domains exhibit compact packing characteristics. It is demonstrated that in polymer B, AMPS segments are predominantly present as ionic clusters contributing to a high pKa at about 9.50 for a low alpha of 0.20. From the results of interfacial adsorption estimations at air/solution and water/hexane interface, it is shown that open coil structures provided under high pH (>9.0) conditions promote efficiency of adsorption. This is shown from higher surface excess concentration (F) and lower interfacial area (a) estimated using Gibbs adsorption isotherm equation. For example, at water/hexane interface, polymer A exhibits Gamma of 1.20 x 10(-3) moles/1000 m(2) at pH 3.2 and 1.97 x 10(-3) moles/1000 m(2) at pH 10.0. Significantly, in case of polymer B consisting of ionic clusters of AMPS, adsorption at the liquid/liquid interface is more efficient in comparison to polymer A at all pH. (C) 2008 Wiley Periodicals, Inc.