Amphiphilic and thermosensitive copolymers based on pullulan and Jeffamine®: Synthesis, characterization and physicochemical properties

The synthesis of thermosensitive copolymers based on pullulan and polyether amine was performed in water using a water-soluble carbodiimide and N-hydroxysuccinimide as activators. Jeffamine® M2005 was chosen as a polyether to impart thermosensitive character to the copolymer. Pullulan was modified into carboxymethylpullulan, to bring carboxylate groups to the polysaccharide so as to further the grafting reaction. The copolymers were characterized by FT-IR, 1H NMR spectroscopy and molecular weights measurements (by SEC coupled with MALS/DRI/Viscometer lines). The thermosensitive behaviour of CMP-g-M2005 copolymers was studied by fluorescence spectroscopy of pyrene, by rheometry and microDSC measurements. The sol–gel transition temperature was found dependent on the solvent, the grafting degree of M2005 and the concentration of the copolymer. For example it was 35 °C in water, 28 °C in acid buffer (0.1 M, pH 5.4) and 26 °C in saline phosphate buffer (0.15 M, pH 7.4) for a grafting degree of 0.20 at a concentration of 5 wt%.