CHAPTER 4: Use of Click Chemistry as a Coupling Strategy for the Synthesis of Miktoarm Star Polymers

Click chemistry methods have been widely used in the synthesis and functional group modification of various tailor-made miktoarm star polymers. As understood from its name, these reactions occur under mild conditions with high efficiency and good tolerance toward many functional groups and solvents. Sharpless-type 1,3-dipolar cycloaddition reactions between acetylene and azide functional groups in the presence of Cu(i) catalysts are regarded as ‘the cream of the crop’ among click reactions and have been frequently employed to construct well-defined miktoarm star polymers and topologies. In addition, Diels–Alder (DA), thiol–ene, atom transfer nitroxide radical coupling (ATNRC), and aldehyde–aminooxy click reactions are also accepted as click reactions in terms of reaction efficiency at mild conditions and functional group selectivity. The combination of controlled polymerization and these efficient and powerful ligation methods yield different types of miktoarm star polymers with well-defined and elegant molecular structures.