Dendritic and hyperbranched polymers from macromolecular units: elegant approaches to the synthesis of functional polymers

This perspective presents the state-of-the-art techniques to synthesize highly branched polymers such as dendrimers and hyperbranched polymers with well-defined linear chains between branch points. These highly branched polymers are essentially the long-chain analogues of conventional dendrimers and hyperbranched polymers and have been given many names, including dendrimer-like, DendriMac, HyperMac, etc. We cover the various synthetic strategies: the direction of synthesis (i.e., core outward or periphery inward) and the building of hyperbranched polymer either through iterative chain growth/branching reactions or from well-defined and reactive building blocks. The first section of this paper focuses on the iterative chain growth/branching reactions. These reactions have been used to create long-chain analogues of dendrimers. The second section highlights the modular synthesis of long-chain analogues of dendrimers following traditional dendrimer chemistry, based on divergent or convergent synthesis, and using linear polymers, or macromonomers, as building units. The third section outlines the modular synthesis of hyperbranched polymers via single step addition of macromonomers. The final section of this perspective highlights other related syntheses of long-chain hyperbranched polymers that do not fit within the groups described above.