Synthesis and characterization of novel amphiphilic block copolymers based on maltoheptaose and poly(ε-caprolactone)

Novel amphiphilic block copolymers consisting of hydrophilic maltoheptaose segments and hydrophobic poly(ε-caprolactone) (PCL) segments were prepared for the first time, and characterized by 1H NMR spectroscopy and GPC analyses. To obtain such a copolymer, the peracetylated maltoheptaose having a hydroxyl group at the reducing end was synthesized from β-cyclodextrin, and then used to initiate the ring opening polymerization of ε-caprolactone in the presence of stannous octoate. By means of fluorescence technique, transmission electron microscopy and dynamic light scattering, it was found that the resulting block copolymers in aqueous solution could self-assemble into nanosize spherical micelles with a narrow unimodal distribution. Moreover, the critical micelle concentration and the size of the self-assembled micelles could be modulated by changing the PCL content in the resultant block copolymer.