Authors Malkoch, M. ; Drockenmuller, E. ; Thibault, R.J. ; Messerschmidt, M. ; Voit, B. ; Hawker, C.J.
Title Complex copolymers: stretching the synthetic boundries via a novel cascade approach
Date 29.04.2005
Number 13099
Abstract Nature, through time and evolution, has assembled proteins, DNA, complex macromolecules using amino acids and nucleotides. It can perform a cascade of different reactions in the proper order, in the presence of several reactive sites and in a controlled fashion. A cascade reaction is described simply as a set of reactions initiated in a sequential manner where structure X attaches to Y forming XY, which is then activated to react with compound Z forming XYZ, Figure 1. These guiding principles have been of great interest for chemists and there currently exist several impressive demonstrations of how scientists have mimicked Nature's cascade reactions. For example, the synthesis of natural products, such as the highly complex polycyclic alkaloid, Daphniphyllum, which involves 12 sequential reactions. Despite these examples, the structures achieved through tedious lab synthesis are merely simple building blocks compared to what Nature has accomplished. The need for sophisticated polymers to be used in cutting edge applications is increasing dramatically and various methods for their preparations have been developed. However, the final tuning of their structures through specific modifications is still an area to be explored. Most strategies used for polymer functionalization involve the formation of amide, ester and ether bonds as the starting materials readily available from the enormous pool of commercial compounds. Using click chemistry, Hawker and Sharpless have reported the synthesis of higher generation dendrimers in high yields and purity through simple work-up. The mild reaction conditions combined with unprecedented functional group compatibility allowed the introduction of a variety of functionalities at the periphery. Dendrimers are recognized as unique and monodisperse polymers, the structural perfection of which can only be realized in a highly efficient and stepwise approach. The success of the dendrimer synthesis using the click chemistry approach indicates the possibilities of applying the same strategy for polymer modifications. To increase the complexity and generate new synthetic strategies to functionalize polymers, the compatibility and efficiency of click chemistry towards other modification techniques is explored in a cascade fashion. The materials synthesized, ranging from small molecules to dendrimers and linear polymers, were accomplished by combining click chemistry with common linking reactions, such as esterification, amidation, and etherification.
Publisher Polymer Preprints
Citation Polymer Preprints 46 (2005) 11
Tags copolymers; synthesis; reaction mechanisms; dendrimers; hydrophobicity

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