Supergravity and In-Situ Evaporation Induced Well-Aligned and Self-Crosslinked 2D Material-Based Thin Films

Assembling two-dimensional (2D) nanoflakes into freestanding ultrathin films while maintaining their superior mechanical and functional properties can enable a wide range of applications. In this work, a versatile method is presented, based on supergravity drop casting combined with in-situ evaporation to fabricate 2D thin films with excellent alignment, self-crosslinking capability, and high compactness. Using this approach, free-standing graphene oxide (GO) films with a thickness as low as 250 nm, an orientation factor of 0.92, and a record-high tensile strength of 540 MPa are achieved. The supergravity field confines the 2D flakes within an ultrathin liquid layer and generates strong all-directional shear forces that induce superalignment. Simultaneously, in-situ evaporation accelerates dehydration and promotes ester bond formation between adjacent flakes, enabling self-directed crosslinking. This method is further demonstrated to be applicable for creating patterned films and assembling other 2D materials such as MXene, graphene, and their heterostructures. The process, therefore, provides a universal and scalable platform for constructing high-performance 2D building blocks for flexible electronics, membranes, and heterostructured devices.