| Summary: | Chain-end functionalised polymers are highly sought after in polymer research as these polymers contain unique properties and functionalities that give rise to many important applications. Chain-end azido-functionalised polymers are important functional polymers as the versatile azido moiety can be easily derivatized to other functionalities like amine, nitrile, isocyanate, etc. Furthermore, azide functional groups are extremely crucial in click chemistry endeavours to form block copolymers. Given the high versatility and broad applicability of azide polymers in the synthetic polymer field, we studied and developed a highly rapid and efficient system for the synthesis of chain-end azido-functionalised polymethacrylates (polymethacrylate-N3). The use of highly soluble tetrabutylammonium azide (BNN3) allows us to perform azidation in toluene via a Finkelstein-type route. Model studies employing small molecular weight tertiary alkyl iodide and alkyl bromide revealed that 1.5 equiv of BNN3 at 50 °C in toluene is the optimised condition for azidation of polymethacrylates. The small molecular weight model studies also comprised of compounds that represent polyacrylate and polystyrene systems.
The novel and ultrafast azidation was further applied to synthesize azido-end polymethacrylates from iodide- and bromide-end polymethacrylates. Quantitative azidation of PMMA-I and PMMA-Br was successfully achieved in 30 min and 1 h respectively by confirming the extent of functionalisation via azide-alkyne click reaction. A library of azido-end polymethacrylate were synthesised using BNN3, indicating a broad application scope in polymer synthesis.
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