Synthesis of well-defined macromonomers by the combination of atom transfer radical polymerization and a click reaction

This article presents a new strategy for synthesizing a series of well-defined macromonomers. Bromine-terminated polystyrene and poly(t-butyl acrylate) with predetermined molecular weights and narrow distributions were prepared through the atom transfer radical polymerization of styrene and t-butyl acrylate initiated with ethyl 2-bromoisobutyrate. Then, azido-terminated polymers were obtained through the bromine substitution reaction with sodium azide. Catalyzed by CuBr/ N,N,N ',N '',N ''-pentamethyldiethylenetriamine, the azido end group reacted with propargyl methacrylate via a 1,3-dipolar cycloaddition reaction, and omega-methacryloyl-functionalized macromonomers were thus obtained. The end-group transformation yields were rather high, as characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectra and H-1 NMR analysis. By this effective and facile approach, some novel macromonomers that otherwise are difficult to achieve, such as poly(ethylene oxide)-block-polystyrene, were easily prepared. Radical homopolymerizations of these macromonomers were performed, and a series of comb polymers were prepared. (c) 2006 Wiley Periodicals, Inc.