| AVS 62nd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Tuesday Sessions |
| Session NS+SP-TuM |
| Session: | Nanoscale Imaging and Materials Characterization |
| Presenter: | Tobin Filleter, University of Toronto, Canada |
| Authors: | C. Cao, University of Toronto, Canada M. Daly, University of Toronto B. Chen, University of Toronto C.V. Singh, University of Toronto Y. Sun, University of Toronto T. Filleter, University of Toronto, Canada |
| Correspondent: | Click to Email |
Graphene oxide (GO) is a layered material comprised of hierarchical features which possess vastly differing characteristic dimensions. GO has been applied as a good candidate for paper-like materials, robust fibers, and reinforcement elements in composites. The use of GO in these materials has been motivated in large part by the predicted high mechanical properties of individual GO monolayers. Recent experiments performed in our research group have measured the strength of GO monolayers to be ~25 GPa [1], which is in good agreement with previously theoretical predictions [2]. Macroscopic papers and fibers synthesized using GO, however, typically exhibit strengths on the order of 10-100’s of MPa’s. GO nanosheets represent the critical hierarchical structure that bridges the length-scale of these monolayer and bulk material architectures.
In this study, the strength and fracture behavior of GO nanosheets were examined in situ with a micro-tensile device operated inside scanning and transmission electron microscopes (SEM/TEM) [3]. The tensile strength of GO nanosheets was measured to be as high as 12 ± 4 GPa, approaching the intrinsic strength of monolayer GO, and orders of magnitude higher than bulk GO papers. During mechanical failure, the nanosheets were observed to undergo intraplaner brittle fracture in highly localized regions through the cross-section of nanosheets due to interlayer load transmission via a hydrogen bond networks as reveled by complimentary Molecular Dynamics simulations.
GO nanosheets were found to exhibit variations in strength that were strongly correlated with the effective volume. This is consistent with Weibull statistics, such that larger GO nanosheets are more likely to possess larger planar defects and adversely impact strength. Furthermore, the Young’s modulus was inversely correlated to sample thickness, and approached that of monolayer GO (~380 GPa) for thin samples. These trends provide strong evidence of the scaling effects on the mechanical properties of GO materials, and help to bridge the understanding of the mechanical behavior of hierarchical GO materials which will ultimately guide application as GO papers and coatings.
[1] C. Cao et al., "High strength measurement of monolayer graphene oxide", Carbon, vol. 81, pp. 497-504, 2014.
[2] J. T. Paci et al., "Computational studies of the structure, behavior upon heating, and mechanical properties of graphite oxide," Journal of Physical Chemistry C, vol. 111, pp. 18099-18111, 2007.
[3] C. Cao et al., "Strengthening in graphene oxide nanosheets: Bridging the gap between interplanar and intraplanar fracture ", Nano Letters, In Revision, 2015.