Chemically modified pullulans II. New hydrophobically substituted derivatives

New hydrophobically substituted pullulans were synthesized, such as (i) neutral derivatives obtained by direct esterification of pullulan with adenine and thymine butyric acid and (ii) ionic derivatives obtained by amidation of carboxymethyl pullulan with aromatic amines (aminopyrene and adenine). Rheological measurements in dilute solutions allowed us to test the influence of the hydrophobic aromatic substituents and of the ionicity of the parent support on the nature of the hydrophobic associations in dilute solutions. The rheological studies on the pullulan derivatives revealed mainly intramolecular hydrophobic associations for both ionic and non-ionic derivatives, suggesting a more compact conformation than that of the precursor. Keywords: hydrophobically modified pullulans, esterification, amidation, condensed aromatic ring, size exclusion chromatography, multi-angle laser light scattering.