Simultaneous reverse and normally

An improved reverse ATRP was developed to take advantage of the ability to use more active catalyst complexes, that is, more readily oxidized complexes,without inaeasing the concentration of copper in the reaction. This procedure was called a simultaneous reverse and normal initiation procedure (SR NI), since the activator and a small fraction of the initiating chains were formed in a reverse ATRP reaction, while the majority of the growing chains were initiated from the added normal ATRP initiator molecule. A limitation of SR NI clarified after development of 2D chromatography is the presence of a small fraaion of polymer chains initiated by the added free radical initiator. ... 

ATRP with simultaneous reverse and normal initiation... 

Gromada J, Matyjaszewski K (2001) Simultaneous reverse and normal initiation in atom transfer radical polymerization. Macromolecules 34 7664-7671... 

Li, M., Jahed, N.M., Min, K., Matyjaszewski, K. Preparation of linear and star-shaped block copolymers by ATRP using simultaneous reverse and normal initiation process in bulk and miniemulsion. Macromolecules 37(7), 2434-2441 (2004)... 

An important improvement was the development of another initiation strategy, dubbed simultaneous reverse and normally initiated (SR NI) ATRP In this technique, a low concentration of active catalyst can be used and block copolymers, although not absolutely free of homopolymer impurities, can be synthesized. The reaction mixture contains an alkyl halide (which may be polymeric or functionalized), a smaller amount of radical source and the oxidatively stable higher oxidation state metal halide complex (deactivator). The reaction starts with the decomposition of the conventional radical source. The formed radicals initiate some chains and reduce the higher oxidation state metal halide complex to afford an ATRP activator, which can then activate the alkyl halide and concurrently mediate normal ATRP. The amount of catalyst used in this technique is determined not by the number of chains but only by its activity. SR NI ATRP has been... 

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