The direct modification of poly(methyl acrylate) (PMA) to obtain functional poly(N-alkyl acrylamide)s is appealing for polymer upcycling but was considered to be an inefficient approach. Recently, several research groups reported the possibility of the direct modification of unactivated poly(acrylate ester)s to obtain functional polymers. Within this contribution, we explored the amidation of PMA with various amines, utilizing triazabicyclodecene (TBD) as an organocatalyst. The reaction conditions can be tuned to provide kinetic control over the functionalization degree of PMA, enabling the synthesis of copolymers consisting of methyl acrylate and N-alkyl acrylamide groups. We demonstrated the utility of the developed approach to synthesize functional polymers with olefin side chains, which were subsequently crosslinked via thiol-ene and Alder-ene chemistry. We also demonstrated accelerated (co-)amidation of aminoalcohols due to neighboring groups. Poly(N-allyl acrylamide) (PAllA) obtained by full amidation of PMA was further exploited to develop new functional hydrogels. Mercaptoethanol (ME) was added during crosslinking as a monofunctional thiol to modulate hydrogel properties in a one-pot procedure, lowering the volume-phase transition temperature of resulting hydrogels with increasing ME content. The remaining allyl groups in PAllA hydrogels can be further utilized for post-gelation modification, e.g. by thiol-containing dyes and drugs. As another example, PMA partially modified by allylamine was utilized for the development of supramolecular materials crosslinked by ureidopyrimidinone dimerization. Overall, TBD-catalyzed amidation is a powerful tool in macromolecular engineering, allowing the full or partial modification of polymers with pendant ester groups and synthesis of photocurable materials. For example, we have additionally utilized this approach for the functionalization of poly(2-oxazoline)s.

Amidation of poly(methyl acrylate) as a versatile upcycling platform towards functional polymers and materials

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