Hydrogen-Bonding Crosslinked Supramolecular Polymer Materials: From Design Evolution of Side-Chain Hydrogen-Bonding to Applications

Hydrogen bonds (H-bonds) are the most essential non-covalent interactions in nature, playing a crucial role in stabilizing the secondary structures of proteins. Taking inspiration from nature, researchers have developed several multiple H-bonds crosslinked supramolecular polymer materials through the incorporation of H-bond side-chain units into the polymer chains. N-acryloyl glycinamide (NAGA) is a monomer with dual amides in the side group, which facilitates the formation of multiple dense intermolecular H-bonds within poly(N-acryloyl glycinamide) (PNAGA), thereby exhibiting diverse properties dependent on concentration and meeting various requirements across different applications. Moreover, numerous attempts have been undertaken to synthesize diverse NAGA-derived units through meticulous chemical structure regulation and fabricate corresponding H-bonding crosslinked supramolecular polymer materials. Despite this, the systematic clarification of the impact of chemical structures of side moieties on intermolecular associations and material performances remains lacking. The present review will focus on the design principle for synthesizing NAGA-derived H-bond side-chain units and provide an overview of the recent advancements in multiple H-bonds crosslinked PNAGA-derived supramolecular polymer materials, which can be categorized into three groups based on the chemical structure of H-bonds units: (1) monomers with solely cooperative H-bonds; (2) monomers with synergistic H-bonds and other physical interactions; and (3) diol chain extenders with cooperative H-bonds. The significance of subtle structural variations in these NAGA-derived units, enabling the fabrication of hydrogen-bonded supramolecular polymer materials with significantly diverse performances, will be emphasized. Moreover, the extensive applications of multiple H-bonds crosslinked supramolecular polymer materials will be elucidated.