Tailoring graphene oxide assemblies by pinning on the contact line of a dissolving microdroplet†
The controlled dissolution of microdroplets on a supporting substrate is an effective approach that can be used to tune the assembled microstructure of basic units suspended within the droplet. In this work, we studied the self-assembly of two-dimensional graphene oxide (GO) nanosheets driven by the dissolution of a microdroplet situated at the interface between a solid substrate and the surrounding liquid phase. We found that although uniform microstructures form at the liquid–liquid interface of the droplets, the contact between the droplet and the substrate can give rise to a variety of different morphologies near the base of the droplet. In particular, pinning effects at the boundary of the dissolving droplet on the substrate lead to non-spherical GO assemblies. The results in this work demonstrate the possibility that tailored three-dimensional architectures of nanosheets assembled in a dissolving droplet may be achieved through control of the wetting properties of the droplet on the supporting substrate.