title: Multifunctionality and control of the crumpling and unfolding of large-area graphene.
abstract: Crumpled graphene films are widely used, for instance in electronics, energy storage, composites and biomedicine. Although it is known that the degree of crumpling affects graphene's properties and the performance of graphene-based devices and materials, the controlled folding and unfolding of crumpled graphene films has not been demonstrated. Here we report an approach to reversibly control the crumpling and unfolding of large-area graphene sheets. We show with experiments, atomistic simulations and theory that, by harnessing the mechanical instabilities of graphene adhered on a biaxially pre-stretched polymer substrate and by controlling the relaxation of the pre-strains in a particular order, graphene films can be crumpled into tailored self-organized hierarchical structures that mimic superhydrophobic leaves. The approach enables us to fabricate large-area conductive coatings and electrodes showing superhydrophobicity, high transparency, and tunable wettability and transmittance. We also demonstrate that crumpled graphene-polymer laminates can be used as artificial-muscle actuators.
authors: Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA.
authors: Jianfeng
authors: J
authors: Zang
authors: Seunghwa
authors: S
authors: Ryu
authors: Nicola
authors: N
authors: Pugno
authors: Qiming
authors: Q
authors: Wang
authors: Qing
authors: Q
authors: Tu
authors: Markus J
authors: MJ
authors: Buehler
authors: Xuanhe
authors: X
authors: Zhao
mesh_terms: D006108:Graphite / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology; D010316:Particle Size; D013499:Surface Properties
chemical_list: D006108:Graphite