Diversification of Acrylamide Polymers via Direct Transamidation of Unactivated Tertiary Amides

Abstract

Postpolymerization modification offers a versatile strategy for synthesizing complex macromolecules, yet modifying acrylamide polymers like poly(N,N-dimethylacrylamide) (PDMA) is notoriously challenging due to the inherent stability and low reactivity of amide bonds. In this study, we unveil a novel approach for the direct transamidation of PDMA, leveraging recent advances in the transamidation of unactivated tertiary amide substrates. By exploiting photoiniferter polymerization, we extended this direct transamidation approach to ultrahigh-molecular-weight (UHMW) PDMA, showcasing the unprecedented postpolymerization modification of synthetic polymers exceeding 10 6 g/mol. We also designed acrylamide copolymers comprising both the moderately reactive N-methyl-N-phenyl tertiary amides, along with the less reactive, fully alkyl-substituted N,N-dimethyl amides inherent to PDMA. This disparate reactivity enabled a sequential, chemoselective transamidation by initially targeting the more reactive pendant aryl amides with less nucleophilic aromatic amines, and second, transamidating the untouched N,N-dimethyl amide moieties with more nucleophilic aliphatic amines, yielding a uniquely diversified acrylamide copolymer. This work not only broadens the scope of postpolymerization modification strategies by pioneering direct transamidation of unactivated amides but also provides a robust platform for the design of intricate macromolecules, particularly in the realm of UHMW polymers.

β-Triketones as Reactive Handles for Polymer Diversification via Dynamic Catalyst-Free Diketoenamine Click Chemistry

“…To date, PPM of synthetic UHMW polymers, specifically those with molecular weights exceeding 10 6 g mol –1 , has been primarily reported for acrylamide polymers, most notably poly­( N , N -dimethylacrylamide) (PDMA) . Considering the growing interest in engineering functional UHMW polymers that mimic the size of naturally occurring macromolecules like mucins and lubricins, − coupled with recent advancements in accessing UHMW acrylamide and (meth)­acrylate polymers via photoiniferter polymerization, − we identified a unique opportunity to develop TK-containing methacrylate polymers with unprecedented chain lengths.…”

Oxidative Polymer Degradation via Cope Elimination

“…To address challenges in plastic persistence, it is vital to develop highly tunable, degradable materials. − With this in mind, poly(β-amino esters) (PBAEs) and poly(amido amines) (PAMAMs) have garnered interest in biomedical and materials science due to their facile synthesis, controllable degradation lifetime, and biocompatibility. − These materials are typically prepared via bulk aza-Michael polymerization of diacrylates/acrylamides with primary amines. , This combinatorial approach allows for the preparation of materials libraries with highly customizable backbone and pendent group chemistries without the need for purification. − Because of this structural diversity and ease of synthesis, PBAEs and PAMAMs have been extensively investigated as degradable polymeric platforms in gene delivery, ,, bioimaging, , three-dimensional (3D) printing, , and dynamic covalent networks. − …”