Self-Assembly of Ultralarge Graphene Oxide Nanosheets and Alginate into Layered Nanocomposites for Robust Packaging Materials

The assembly of graphene oxide (GO) nanosheets into bioinspired nacre-like nanocomposites is a potential strategy for the development of robust alternative packaging materials. At sufficiently high concentrations, the self-assembly of ultralarge GO into liquid crystals (LC) in colloidal suspensions with alginate biopolymer is observed. Studying freeze-dried partially cast nanocomposites reveals the gradual reorientation and merging of these LC domains during evaporation. Evaporation of LC alginate-GO suspensions yields nanocomposite films with highly ordered layered microstructures, with excellent mechanical properties, thermal stability, and moisture barrier performance. Spectroscopic studies and comparison with theoretical models establish the role of hydrogen-bonding interactions between the components and confirm the parallel alignment of ultralarge GO above 2 wt %, corresponding to the formation of LC domains in aqueous suspension. The insights afforded by this study can help guide the commercial development of strong, environmentally friendly biopolymer-GO nanocomposites.