With increased PS concentration, the amide and methylester groups' relative contribution to interfacial interactions develops by the formation of H-bonds between these PS' groups (PS-C=O⋯HN-PS); these interactions ultimately decrease surface hydrophilicity. Repulsive electrostatic forces between the N-amide of PS and the protonated surface hydroxyl groups of goethite keeps this positively charged group away from the goethite interface. However, it has been suggested that amide groups in amidated-PS strengthen the self-assembly structure by Hbond formation (i.e., organic-organic interactions) at low pH where electrostatic repulsion between the chains is minimized. In our study, the negative repulsive force within PS chains, originating from carboxylate residues (37.1% substitution), is minimized by the interaction with goethite.