Toward tunable amphiphilic copolymers via CuAAC click chemistry of oligocaprolactones onto starch backbone

Starch-based tunable amphiphilic copolymers are easily obtained by grafting polycaprolactone chains via 1,3 dipolar Copper-Catalyzed Azide-Alkyne Cycloaddition (click chemistry CuAAC), starting from propargylated starch and azido oligocaprolactones with different chain lengths as the precursors. The copolymers are characterized by H-1 and C-13 NMR, from which a degree of substitution of starch can tentatively be deduced. Besides these bulk characterizations, the surface of the functionalized starch is also characterized by XPS which confirms the triazole formation, particularly through the deconvolution of the N 1s peak, and by ToF-SIMS which, not only confirms the surface modification, but also highlights the disappearance of the Cu+ cations. The solubility and swelling behaviours of these copolymers have been investigated, which clearly show the dependence both on the solvent and the PCL chain length. These investigations highlight the swelling dependence on the Sd component of the Hansen solubility parameter of solvents. Finally, at low concentration, they present the capacity to organize themselves in aggregates in aqueous solutions, as seen from TEM and DLS investigations. (C) 2013 Elsevier Ltd. All rights reserved.