Recent advances in zwitterionic hydrogels: structure, applications and challenges

Zwitterionic hydrogels, with their unique molecular structures, exhibit exceptional properties such as superior hydrophilicity, ionic conductivity, antifouling and adhesion properties, making them a research hotspot in the field of desalination, water harvesting, biomedical, flexible sensing, and energy storage. The structure-performance relationship is crucial for tailoring zwitterionic hydrogels in practical applications. Herein, we aim to investigate the effect of structure, such as charge distribution, crosslinking density, and network architecture, on the performance in terms of hydrophilicity, ionic conductivity, and antibacterial/antifouling and adhesive properties of zwitterionic hydrogels. Furthermore, suggestions are provided for optimizing the hydration, anti-polyelectrolyte, charges and dipole, and electrostatic interaction of zwitterionic hydrogels, thus enhancing the hydrophilicity, ionic conductivity, antifouling and adhesion properties for wide applications such as seawater desalination, atmospheric water collection, marine antifouling coating, biomedicine, energy storage and flexible sensors. Finally, the opportunities and outline associated with zwitterionic hydrogels are elaborated.