Association states of multisensitive smart polysaccharide–block-polyetheramine copolymers

The water soluble properties of different copolymers based on pullulan–block-polyetheramine have been deeply studied. The polyetheramine group (PEA) corresponding to a propylene oxyde/ethylene oxyde ratio (PO/EO) of 29/6, is condensed, via amine link, to pullulans with various chain lengths. Different polysaccharide/PEA (PS/PEA) ratio copolymers have been investigated through macroscopic (cloud point, enthalpy) and mesoscopic scale approaches (critical aggregation concentration (CAC), mean number average hydrodynamic diameter (Dh) or aggregation number (Nag)). These systems are both pH and/or thermo-sensitive. Finally, it seems that three states can describe such systems (i) isolated copolymers (unimers) below the CAC, (ii) water soluble aggregates above the CAC and whatever the PS/PEA ratio is due to hydrophobic interactions and (iii) non-soluble aggregates (above the critical temperature) due to dehydration of polyetheramine groups but only if PS/PEA ratio is low enough.