Controlled/living radical challenges

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... 

So far, a great number of well-defined macromonomers as branch candidates have been prepared as will be described in Sect. 3. Then a problem is how to control their polymerization and copolymerization, that is how to design the backbone length, the backbone/branch composition, and their distribution. This will be discussed in Sect. 4. In brief, radical homopolymerization and copolymerization of macromonomers to poly(macromonomers) and statistical graft copolymers, respectively, have been fairly well understood in comparison with those of conventional monomers. However, a more precise control over the backbone length and distribution by, e.g., a living (co)polymerization is still an unsolved challenge. 

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