Syntheses and characterization of 16-arm star and star diblock copolymer and AB8 9-miktoarm star copolymer via NMRP and ROP from dendritic multifunctional macroinitiators

A dendritic macroinitiator having 16 TEMPO-based alkoxyamines, Star-16, was prepared by the reaction of a dendritic macroinitiator having eight TEMPO-based alkoxyamines, [G-3]-OH, with 4,4'-bis(chlorocarbonyl)biphenyl. The nitroxide-mediated radical polymerization (NMRP) of styrene (St) from Star-16 gave 16-arm star polymers with PDI of 1.19-1.47, and NMPR of 4-vinylpyridine from the 16-arm star polymer gave 16-arm star diblock copolymers with PDI of 1.30-1.43. The ring-opening polymerization of.-caprolactone from [G-3]-OH and the subsequent NMRP of St gave AB(8) 9-miktoarm star copolymers with PDI of 1.30-1.38. The benzyl ether linkages of the 16-arm star polymers and the AB(8) 9-miktoarm star copolymers were cleaved by treating with Me3SiI, and the resultant poly(St) arms were investigated by size exclusion chromatography (SEC). The SEC results showed PDIs of 1.23-1.28 and 1.18-1.22 for the star polymers and miktoarm stars copolymers, respectively, showing that they have well-controlled poly(St) arms. (c) 2006 Wiley Periodicals, Inc.