Understanding Mechanical Response of Elastomeric Graphene Networks

Abstract

Ultra-light porous networks based on nano-carbon materials (such as graphene or carbon nanotubes) have attracted increasing interest owing to their applications in wide fields from bioengineering to electrochemical devices. However, it is often difficult to translate the properties of nanomaterials to bulk three-dimensional networks with a control of their mechanical properties. In this work, we constructed elastomeric graphene porous networks with well-defined structures by freeze casting and thermal reduction, and investigated systematically the effect of key microstructural features. The porous networks made of large reduced graphene oxide flakes (>20 μm) are superelastic and exhibit high energy absorption, showing much enhanced mechanical properties than those with small flakes (<2 μm). A better restoration of the graphitic nature also has a considerable effect. In comparison, microstructural differences, such as the foam architecture or the cell size have smaller or negligible effect on the mechanical response. The recoverability and energy adsorption depend on density with the latter exhibiting a minimum due to the interplay between wall fracture and friction during deformation. These findings suggest that an improvement in the mechanical properties of porous graphene networks significantly depend on the engineering of the graphene flake that controls the property of the cell walls.

Self‐Healing Graphene‐Based Composites with Sensing Capabilities

“…With our experimental setup, we have observed a linear relationship between the applied pressure and the measured voltage for pressures up to 500 kPa. This data suggests that deformation of the graphene network in the composite is highly reversible, as it has also been observed for the starting graphene scaffolds …”

“…To overcome these limitations, we have confined the self‐healing polymer in rGO networks with microscopic porosity. The networks are prepared through the freeze casting of graphene oxide (GO) suspensions followed by thermal reduction . The technique uses the directional freezing of the suspensions to form networks with a characteristic structure formed by long channels (hundreds of microns) packed in a honeycomb arrangement.…”

Silane bonded graphene aerogels with tunable functionality and reversible compressibility

“…In comparison, the excellent superelasticity and cycling performance of the silane-b-RGO aerogels rules out the fracture of cell walls. The smaller pore size and the thinner cell wall with SCAs bonded and strengthened RGO sheets will improve the interactions among sheets, providing better recovery and producing more energy dissipation due to the friction among sheets [62]. These responsible mechanisms would be maximized due to the corrugated nature of the graphene sheets and their entanglement and tight packing in the cell wall, The maximum stress of these aerogels in Fig.…”

Effect of flake size on the mechanical properties of graphene aerogels prepared by freeze casting

“…Graphene aerogel has aroused increasing attention from interdisciplinary elds for its wide potential applications such as so electronic sensors, energy absorbers, oil-removal materials, and so on. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Its mechanical properties, including strength, robustness, and fatigue resistance are highly crucial for those applications. 1,7,8,[20][21][22][23][24][25] From a mechanical point of view, graphene aerogels are highly porous, lightweight and thus usually fragile.…”

“…Many techniques including chemical vapor deposition (CVD), 26 sol-gel transition, 27 hydrothermal method, [28][29][30] and freeze-casting 1,4,6,31,32 have been developed to improve the mechanical performance of graphene aerogels, usually by controlling their multiscale architecture at both the macro and micro scales. However, it remains difficult to translate the unique intrinsic mechanical properties of single GO ake into a 3-dimensional (3D) macroscopic aerogel.…”