Graphene oxide-based composite hydrogels with self-assembled macroporous structures

The self-assembly technique provides a new and simple route for designing porous hydrogels. At present, most of the studies in graphene oxide (GO)-polymer hydrogels are concentrated on mechanical reinforcement. Developing a self-assembled GO-based porous hydrogel along with swelling and mechanical merits is still challenging, yet very interesting and desirable for practical applications. Herein, we report self-assembled GO-based macroporous composite hydrogels by integrating GO sheets and chitosan-based hydrogel networks. GO sheets, containing adequate hydrophilic functional groups, can be dispersed well and thereby they form self-assembled supramolecular structures with polymer chains by effective intermolecular interactions (e.g., hydrogen bonding, electrostatic attraction or covalent bonding). Surprisingly, an extremely low amount (0.05-0.30 wt%) of GO can remarkably affect the architecture of hydrogel networks, leading to the formation of macroporous composite hydrogels. On the whole, the GO-based polymer composite hydrogels possess both macroporous structures (10-100 mm) and enhanced mechanical performance, yet can still retain the similar swelling properties of their parent polymeric hydrogel. Therefore, this study provides a simple route for fabricating porous hydrogels, which could find some potential applications in wastewater treatment or biomedical engineering.