Supramolecular hydration structure of graphene-based hydrogels: density functional theory, green chemistry and interface application

Natural hydration shells are discovered to play an essential role in the structure and function of biomolecules (deoxyribonucleic acid, protein and phospholipid membrane). Hydration layers are also important to the structure and property of artificial graphene-based materials. Our recent researches prove that graphene-based hydrogels are supramolecular hydration structures that preserve graphene nanosheets from irreversible stacking via van der Waals forces and π-π interactions. In this manuscript, density functional theory (DFT) and high performance computing (HPC) are used for modeling and calculating van der Waals force between graphene nanosheets in water-intercalated AB bilayer graphene structures. A layer of water molecules significantly decreases the intersheet van der Waals force. Experimentally, a novel hydrogel of graphene oxide – silica gel – zinc hydroxide (GO-SG-ZH) is synthesized to demonstrate the advantages of hydrated hydrogel structure in comparison with dry powder structure. The synthesis of graphene-based hydrogels is a green chemistry approach to attain extraordinary properties of graphene-based nanostructures. Hydration forces in the hydrogel prevent van der Waals stacking and graphene agglomeration. Analytical characterizations exhibited moisture contents, three-dimensional structures, elemental compositions, functional groups and antibacterial activities. Non-stacking state of graphene-based nanosheets in GO-SG-ZH hydrogel was suitable for direct brush painting on polymer substrates, typically polylactide films. GO-SG-ZH coating on polylactide film was antibacterial and stable in aqueous food simulants for one month. In general, supramolecular graphene-based hydrogels are bioinspired hydration structures to advance nanoscale properties and nanotechnology applications.