The adsorption of polymer dispersants of the polyisobutenylsuccinimide series has been studied at the
solid/xylene interface. Carbon black was studied as a model solid. Adsorption isotherms were determined,
the enthalpy of adsorption was measured by calorimetry, and the thickness of the adsorbed layer was
obtained from small-angle neutron scattering. The paper emphasizes the structure−properties relationships
with the help of a series of polyisobutenylsuccinimides having different polyamine groups and different
polymer architectures, simple diblock (PIBSI) and comblike structure (polyPIBSI). The polyamine part
ensured a strong adsorption on the solid surface, which increased in strength with the number of amine
groups. In the same way, changing the diblock structure for a comblike one led to an enhanced affinity
of the polymer for the solid surface. The adsorption was enthalpic but the Gibbs free energy of adsorption
remained moderate because of a large entropy loss during adsorption. There was an enthalpy−entropy
compensation phenomenon. Below a concentration of 70 mmol/m3, the polymers adsorbed as a 30 Å thick
monolayer and the adsorption phenomenon was irreversible, due to the polymeric nature of the polar part.
A drastic increase of adsorbed amount took place for higher concentrations. The formation of reverse
hemimicelles was assumed as the origin of this phenomenon. The supplementary adsorption was reversible,
showing that the polymer−polymer interactions were weaker than the polymer−surface interactions.
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