Spatio-Resolved Hyperbranched Graft Polymerized Surfaces by Iniferter-Based Photograft Copolymerization

Two different types of three-generation hyperbranched graft surfaces with parent chain (stem), daughter chain (branch chain), and granddaughter chain (twig chain) were sequentially prepared by iniferter ( ini tiator−trans fer agent− ter minator)-based quasi-living radical graft copolymerization using photolysis of the benzyl N,N -diethyldithiocarbamate (DC) group. The graft copolymerization of chloromethylstyrene (CMS) with N,N -dimethylacrylamide (DMAAm) or N,N -dimethylaminoethyl methacrylate (DMAEMA) was initiated on DC-derivatized surfaces under ultraviolet irradiation, followed by dithiocarbamylation on CMS units in the graft copolymer chains. The repeated cycles of photopolymerization/dithiocarbamylation provided successively higher generations of graft architectures. The stepwise progress of the branching stage was evidenced with changes in surface elemental composition and wettability and visualized by dye staining. From the typical force-versus-distance curves obtained by atomic force microscope measurement, some structural information of graft polymers was estimated.