Direct synthesis of tetrazine functionalities on polymer backbones

Tetrazine mediated inverse Electron Demand Diels–Alder Reaction (IEDDA) is an important modification technique due to its high selectivity and super-fast kinetics. Incorporation of tetrazine moieties on polymer chains requires multistep synthetic pathways and a post-polymerization step leading to functional polymeric materials. Such approaches involve separate syntheses of polymer and the molecule which will be employed in modification. Herein, we introduce a straightforward synthetic approach for direct synthesis of tetrazine groups on polymers as side chains. As model systems, tetrazine functional poly(N-isopropylacrylamide)-and poly(ethylene glycol)-based polymers from corresponding precursor polymers with nitrile moieties as pendant groups are prepared and IEDDA Click Reaction is achieved with trans-cyclooctene derivatives. The click reaction is monitored by both NMR and UV–vis spectroscopies.