Dynamic and reversible bonds in polymeric membrane fabrication: towards recyclability-by-design

The increasing demand for sustainable separation technologies has intensified interest in polymeric membranes due to their energy efficiency and versatility. However, many conventional membranes are fabricated from permanently crosslinked or non-degradable polymers, limiting their recyclability and contributing to environmental waste. In this review, the integration of dynamic bonds into membrane materials is explored, focusing on their potential to enable reprocessability, repairability and recyclability. First, a concise background summarizing the most essential aspects of membrane science is presented. Next, dynamic bonding strategies commonly employed in polymer science are introduced, highlighting the promise in applying such chemistries specifically to membrane fabrication. Then, literature examples of membranes incorporating those dynamic bonds are evaluated for their impact on membrane properties and recyclability potential. On one hand, physical/non-covalent/ supramolecular interactions are examined, including van der Waals interactions, π-π stacking, hydrogen bonding, ionic bonding and metal-ligand coordination. On the other hand, at the core of the review, the more stable and less environmentally sensitive dynamic covalent bonds (DCBs) are discussed. Both well-explored Diels-Alder (DA) chemistry and other mechanisms e.g. imine exchange, transesterification, and disulfide bonds are discussed. Lastly, challenges of dynamic networks related to a balance between stability and reversibility are discussed, in membrane-relevant conditions: water, extreme pH, organic solvents, high temperature and pressure. This review aims to serve as a foundation for future research into sustainable recyclable membrane technologies driven by dynamic polymer design.