Synthesis of Hyperbranched Multiarm Star Block Copolymers and Their Application as a Drug-Delivery System

A novel hyperbranched multiarm star block copolymers was synthesized. The atom transfer radical polymerization initiators were anchored on the surfaces by the reaction of amino-functionalized silica modified by 3-aminopropyltriethoxysilane with α -bromoisobutyryl bromide. The composites (SNs- g -HPCMS- b -PHEMA- b -PNIPAAm) with silica nano particles as core and hyperbranched star block copolymers as arms was prepared by iron(III)-mediated surface-initiated polymerization with FeCl 3 ·6H 2 O as catalyst, triphenylphosphine as ligand, ascorbic acid as reducing agent, N , N -dimethylformamide as solvent, and 4-chloromethylstyrene, 2-hydroxyethylmethacrylate, and N -isopropylacrylaminde as monomers, respectively. The resultant products were characterized by Fourier-transform infrared spectroscopy, N 2 adsorption/desorption measurements, thermogravimetric analysis, differential scanning calorimeter, and transmission electron micrographs. With aspirin as the model drug, the drug-release behavior of the hybrid materials was studied. The release behavior could be controlled by the temperature, which will have potential applications in biomedicine and biotechnology. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21375; View this article online at wileyonlinelibrary.com . DOI 10.1002/adv.21375