Programmable Amine Copolymers from Keteniminium-Mediated Post-Polymerization Modification

Abstract

Amine-containing polymers are highly sought after for a multitude of applications, yet their direct synthesis is often hindered by the inherent nucleophilicity of the amine functionality. While postpolymerization modification (PPM) offers a viable alternative, most strategies rely on designer-activated polymer precursors. Herein, we report a one-pot reductive PPM of unactivated poly(dialkylacrylamide)s to access a diverse array of amine-containing functional copolymers. This approach leverages an amide activation strategy using trifluoromethanesulfonic anhydride (Tf2O) to generate electrophilic keteniminium ion intermediates. Subsequent trapping with Grignard reagents and in situ reduction of the resulting iminium species yields functional tertiary amines that are proximal to the polymer backbone. This approach avoids the need for activated monomers and enables the preparation of copolymers formally arising from acrylamide and allyl amine monomers with tunable physical properties. Importantly, straightforward quaternization of the newly installed pendant amines furnishes cationic polymers that exhibit promising antimicrobial activity. This work expands the scope of unactivated poly(acrylamide) functionalization, providing a robust platform for the discovery of bioactive polymeric materials.