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 -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. (c) 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21375; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21375