Strengthening in Graphene Oxide Nanosheets: Bridging the Gap between Interplanar and Intraplanar Fracture.
Graphene oxide (GO) is a layered material comprised of hierarchical features which possess vastly differing characteristic dimensions. GO nanosheets represent the critical hierarchical structure which bridges the length-scale of monolayer and bulk material architectures. In this study, the strength and fracture behavior of GO nanosheets were examined. Under uniaxial loading, the tensile strength of the nanosheets was measured to be as high as 12 ± 4 GPa, which approaches the intrinsic strength of monolayer GO and is orders of magnitude higher than that of bulk GO materials. During mechanical failure, brittle fracture was observed in a highly localized region through the cross-section of the nanosheets without interlayer pull-out. This transition in the failure behavior from interplanar fracture, common for bulk GO, to intraplanar fracture, which dominates failure in monolayer GO, is responsible for the high strength measured in the nanosheets. Molecular dynamics simulations indicate that the elastic release from the propagation of intraplanar cracks initiates global fracture due to interlayer load transmission through hydrogen bond networks within the gallery space of the GO nanosheets. Furthermore, the GO nanosheet strength and stiffness were found to be strongly correlated to the effective volume and thickness of the samples, respectively. These findings help to bridge the understanding of the mechanical behavior of hierarchical GO materials and will ultimately guide the application of this intermediate scale material.
Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, Ontario M5S 3G8, Canada.
Changhong
C
Cao
Department of Materials Science and Engineering, University of Toronto , Toronto, Ontario M5S 3E4, Canada.
Matthew
M
Daly
Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, Ontario M5S 3G8, Canada.
Brandon
B
Chen
Department of Materials Science and Engineering, University of Toronto , Toronto, Ontario M5S 3E4, Canada.|Hitachi High-Technologies Canada, Inc., 89 Galaxy Blvd, Suite 14, Toronto, Ontario M9W 6A4, Canada.
Jane Y
JY
Howe
Department of Materials Science and Engineering, University of Toronto , Toronto, Ontario M5S 3E4, Canada.
Chandra Veer
CV
Singh
Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, Ontario M5S 3G8, Canada.
Tobin
T
Filleter
Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, Ontario M5S 3G8, Canada.
Yu
Y
Sun
Graphene oxide; fracture; mechanical properties; molecular dynamics; nanomechanical testing