Ultrafast and reversible multiblock formation by the SET-Nitroxide radical coupling reaction
Kulis, Jakov, Bell, Craig A., Micallef, Aaron S., & Monteiro, Michael J. (2010) Ultrafast and reversible multiblock formation by the SET-Nitroxide radical coupling reaction. Australian Journal of Chemistry, 63(8), pp. 1227-1236.
The single electron transfer-nitroxide radical coupling (SET-NRC) reaction has been used to produce multiblock polymers with high molecular weights in under 3 min at 50◦C by coupling a difunctional telechelic polystyrene (Br-PSTY-Br)with a dinitroxide. The well known combination of dimethyl sulfoxide as solvent and Me6TREN as ligand facilitated the in situ disproportionation of CuIBr to the highly active nascent Cu0 species. This SET reaction allowed polymeric radicals to be rapidly formed from their corresponding halide end-groups. Trapping of these carbon-centred radicals at close to diffusion controlled rates by dinitroxides resulted in high-molecular-weight multiblock polymers. Our results showed that the disproportionation of CuI was critical in obtaining these ultrafast reactions, and confirmed that activation was primarily through Cu0. We took advantage of the reversibility of the NRC reaction at elevated temperatures to decouple the multiblock back to the original PSTY building block through capping the chain-ends with mono-functional nitroxides. These alkoxyamine end-groups were further exchanged with an alkyne mono-functional nitroxide (TEMPO–≡) and ‘clicked’ by a CuI-catalyzed azide/alkyne cycloaddition (CuAAC) reaction with N3–PSTY–N3 to reform the multiblocks. This final ‘click’ reaction, even after the consecutive decoupling and nitroxide-exchange reactions, still produced high molecular-weight multiblocks efficiently. These SET-NRC reactions would have ideal applications in re-usable plastics and possibly as self-healing materials.
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|Item Type:||Journal Article|
|Keywords:||multiblock polymer, nitroxide, radical coupling, single electron transfer-nitroxide radical coupling, click reaction|
|Subjects:||Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Nanochemistry and Supramolecular Chemistry (030302)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Synthesis of Materials (030306)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Theory and Design of Materials (030307)
|Divisions:||Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
|Deposited On:||02 Dec 2015 02:56|
|Last Modified:||10 Dec 2015 02:33|
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