Living radical polymerization Lewis acids

The polystyrene obtained by living cationic polymerization with R—Cl/Lewis acid possesses a carbon-chlorine terminal that is subsequently used for the living radical polymerizations of acrylates and methacrylates to give block copolymers such as B-65 to B-67 376-378... 

Lutz, J. R Jakubowski, W. Matyjaszewski, K. Controlled/living radical polymerization of methacrylic monomers in the presence of Lewis acids Influence on tacticity. Macromol. Rapid Commun. 2004, 25, 486-492. 

With >350 original papers and >30 reviews, he has received, among others, the Award of the Society of Polymer Science, Japan (1992), Divisional Research Award of the Chemical Society of Japan (1999), and Arthur K. Doolittle Award of PMSE Division, the American Chemical Society (2002). His research interest includes development of novel precision polymerizations and catalysis (living cationic polymerization with Lewis acid catalysts (1984) and living radical polymerization with transition metal complex catal) (1995)), the synthesis of designed functional polymers, and the nature of polymerization intermediates. 

The regulation of stereochemistry in radical polymerization has thus far proved enormously challenging, being the subject of more than 50 years of intense and innovative research. The relatively recent development of living radical polymerization has revitalized interest in stereocontrol, as the lack of tacticity control is now the greatest obstacle to the synthesis of precisely controlled macromolecules by highly versatile and efficient radical-based processes. Lewis acids (LAs) have been employed in an attempt to... 

Lutz JP, Kirci B, Matyjaszewski K. Synthesis of weU-defined alternating copolymers by controUed/living radical polymerization in the presence of Lewis acids. Macromolecules. 

Su XL, Zhao ZG, Li H, Li XX, Wu PP, Han ZW. Stereocontrol during photo-initiated controUed/living radical polymerization of acrylamide in the presence of Lewis acids. Eur Polym J. 2008 44 1849-1856. 

By using the aluminum porphyrin-Lewis acid system, we attempted the synthesis of a narrow MWD block copolymer from oxetane and methyl methacrylate (MMA). Methacrylic monomers can be polymerized radically and anioni-cally but not cationically, so a block copolymer of oxetane and methyl methacrylate has never been synthesized. As already reported, methacrylic monomers undergo accelerated living anionic polymerization with the (TPP)AlMe (1, X= Me)-3e system via a (porphinato)aluminum enolate as the growing species. 

Polymerization of vinyl ethers (VE) has been the subject of a considerable amount of theoretical studies. These monomers can be polymerized through radical initiation but the reaction is very slow and leads only to oligomers. Cationic polymerization initiated by a wide variety of Lewis acids is much more efficient and definitely preferred for homopolymer synthesis. Detailed theoretical aspects, and particularly recent developments concerning the controlled/living cationic polymerization of these monomers, have been discussed as well in previous exhaustive review [1,13,98,99] as in the present book (Chapters 4 and 5), and they will no longer be considered here. 

Ge and Sn halides are Lewis acids. SnCl4, which is a strong Lewis acid, can abstract a halogen anion from an alkyl halide to give the alkyl carbocation and is widely used for living cationic polymeriza-tions. ) On the other hand, Ge and Sn iodides (used in this work) are relatively weak Lewis acids. The tacticities of the produced polymers and the complete inhibition of the polymerization in the presence of 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) confirmed that the polymerizations in this work proceeded in a radical mechanism. 

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