Cationic polyelectrolytes from natural building blocks of chitosan and inulin

Novel chitosan-N-inulin graft copolymers with different degree of substitution (DS) of chitosan were synthesized via water-soluble 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide mediated reaction. Chemical structure and composition of the chitosan derivatives was confirmed by chemical analysis, FT-IR, XPS, 1H and 13C NMR spectroscopy, and potentiometry. Chitosan-inulin copolymers were high-molecular-weight hydrophilic products soluble in water in a wide pH range forming extraordinary viscous solutions. Intrinsic viscosity of N-modified chitosans was sharply suppressed by added electrolyte and had tendency to decrease at higher DS of chitosan. pKα values of the chitosan-inulin copolymers determined from potentiometric titration data using Henderson-Hasselbalch equation were in the range 6-7 slightly increasing at higher DS. Novel water-soluble chitosan copolymers retained cationic properties of chitosan and could be used as surface conditioners.