Synthesis and evaluation of a new polar, TIPNO type nitroxide for “living” free radical polymerization

The bromine–magnesium exchange of 2-bromopyridine provides an easy access to a new versatile TIPNO type nitroxide. The synthesis of four functionalized alkoxyamines have been achieved. Polymerizations of styrene and n-butyl acrylate mediated with this new nitroxide exhibited all the expected features of a controlled system. Because of its increase of polarity, this pyridine nitroxide is more efficient than TIPNO for the acrylate polymerization as no added free nitroxide is required, that confirms the strong influence of the polarity of the nitroxide on the efficiency of nitroxide-mediated radical polymerization, result already observed in the case of the polar SG1 nitroxide. Different block copolymers were synthesized. Polystyrene, poly(n-butyl acrylate) and poly(tert-butyl acrylate) blocks were successfully used as macroinitiators for the synthesis of various diblock and triblock copolymers. A representative example of such architecture is given by polystyrene-b-poly(n-butyl acrylate)-b-poly(tert-butyl acrylate) with a PDI of 1.2!