Crumpling of two-dimension graphene oxide (GO) sheets into 3D crumpled ball has been proposed to prevent stacking of 2D GO sheets and retaining high accessible surface area. Crumpling is performed by an aerosol-based process, by aerosolizing a GO suspension and evaporating the solvent causing capillary compression on the GO sheets. Crumpling of GO sheets has not been well understood, especially the relation of computational simulation of crumpling phenomena and experimental results. Here, we present a fundamental model-based on droplet-evaporation theory to understand the crumpling, validated by the experimental results. The model describes the droplet evaporation dynamics, forces present on the GO sheets inside the droplet, and the effect of process parameters (droplet size, GO concentration, solvent type) on the crumpling phenomena. The fundamental forces involved in the crumpling process at low temperatures are capillary force and evaporation momentum force. The model and the experimental results suggest that crumpling is mainly induced by capillary force on the GO sheets rather than evaporation momentum force, and complete solvent evaporation is required for crumpling. Therefore, the extent of crumpling does not depend on the volatility of the solvent but on the surface tension of the solvent. An operating range of process parameters is suggested for producing crumpled structure in the furnace aerosol reactor.
