Nano-patching defects of reduced graphene oxide by cellulose nanocrystals in scalable polymer nanocomposites

Reduced graphene oxide (rGO) has been widely produced by exfoliation of pristine graphite followed by oxidation and reduction. However, a number of defects can be generated during the synthesis of rGO, restricting the ability to scale-up in industrial production of defect-free rGO. The defects in rGO have limited its capacity for utilization of the full potential of the physical properties of polymer nanocomposites, such as gas and water barrier performances. Hence, this study analyzes the nano-patching of rGO defects through hydrophilic interactions of oxygen functional groups in rGO with cellulose nanocrystals (CNCs) in polyvinylidene chloride (PVDC) nanocomposites. For scalable production of defect-engineered PVDC nanocomposite barrier films, the surface energies of rGO and CNC dual nanofiller systems were regulated to prevent phase-separation of nanofillers in the PVDC matrices. The barrier properties of the PVDC/nano-patched filler composites showed drastic reduction of oxygen and water vapor transmission rates corresponding to 0.45 cm³ m⁻² day⁻¹ and 0.52 cm³ m⁻² day⁻¹, respectively, that decreased by 94.2% and 87.9% compared to that of the neat PVDC host. The nano-patching strategy provides novel and effective defect engineering of graphene for polymer nanocomposites.