title: Tailored Crumpling and Unfolding of Spray-Dried Pristine Graphene and Graphene Oxide Sheets.
abstract: For the first time, pristine graphene can be controllably crumpled and unfolded. The mechanism for graphene is radically different than that observed for graphene oxide; a multifaced crumpled, dimpled particle morphology is seen for pristine graphene in contrast to the wrinkled, compressed surface of graphene oxide particles, showing that surface chemistry dictates nanosheet interactions during the crumpling process. The process demonstrated here utilizes a spray-drying technique to produce droplets of aqueous graphene dispersions and induce crumpling through rapid droplet evaporation. For the first time, the gradual dimensional transition of 2D graphene nanosheets to a 3D crumpled morphology in droplets is directly observed; this is imaged by a novel sample collection device inside the spray dryer itself. The degree of folding can be tailored by altering the capillary forces on the dispersed sheets during evaporation. It is also shown that the morphology of redispersed crumpled graphene powder can be controlled by solvent selection. This process is scalable, with the ability to rapidly process graphene dispersions into powders suitable for a variety of engineering applications.
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, 79409, USA.|Department of Chemical Engineering, Texas A&M University, College Station, TX, 77843, USA.
authors: Dorsa
authors: D
authors: Parviz
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, 79409, USA.
authors: Shane D
authors: SD
authors: Metzler
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, 79409, USA.
authors: Sriya
authors: S
authors: Das
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, 79409, USA.
authors: Fahmida
authors: F
authors: Irin
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, 79409, USA.|Department of Chemical Engineering, Texas A&M University, College Station, TX, 77843, USA.
authors: Micah J
authors: MJ
authors: Green
keywords: crumpling; graphene; graphene oxide; spray drying