A series of well defined amphipolar copolyelectrolytes with different molecular architectures namely, block and graft copolymers, consisting of hydrophobic polystyrene and ionic poly(acrylic acid) and random copolymers consisting of hydrophobic isobutene and ionic poly(acrylic acid) segments were synthesized and characterized. The adsorption of these copolyelectrolytes on TiO_2 at pH 9 was studied, whereas both the copolyelectrolytes and the pigment surface were negatively charged. Copolymer pigment interactions were investigated with electrokinetic sonic amplitude (ESA). Sedimentation measurements were performed for screening and verification purposes. The measurements revealed that both the type of the copoiymer structure and the ratio of ionic to hydrophobic structural elements, e.g. the charge density as well as the charge distribution in the macromolecule, play an important role by its adsorption and stabilization behavior. The adsorption mechanism investigated with DRIFT spectroscopy shows H bonding between the carbonyl group and surface hydroxyl groups as well as complexation between the carboxylic groups and metal cations.
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