Dextran-graft-PHBHV copolymers were prepared using click-chemistry. Well defined and functional dextran backbones containing azide groups had been prepared by tosylation and subsequent nucleophilic displacement reaction with sodium azide (DSN3 = 1). Well defined PHBHV oligomers containing an alkyne end group were prepared in a one step reaction by direct alcoholysis from natural polyesters using propargyl alcohol with dibutyltin dilaurate as catalyst. Oligoesters were obtained with molar masses ranging from 900 to 6200 g mol(-1). The Huisgen 1,3-dipolar cycloaddition allowed the preparation of graft copolymers with a content of PHBHV up to DSPHBHV = 0.19. The presence of PHBHV on the dextran backbone led to the formation of stable nanoparticles (160 nm) without surfactant by an emulsion-solvent evaporation method. (C) 2012 Elsevier Ltd. All rights reserved.