Anomalous elasticity and damping in covalently cross-linked graphene aerogels

Abstract

Elasticity in materials is a phenomenon that provides a basis for widespread practical applications in engineering, medicine, and electronics. Most of the conventional materials can withstand only small deformations within the elastic limit, typically below 5% of their original size. Here, we report a graphene aerogel made of covalently cross-linked graphene sheets that exhibits anomalous superelastic behavior up to 92% of compressive and 68% tensile strain. We show that the graphene aerogel has a nonlinear stress-strain characteristic with the compressive and tensile yield strength of 4.5 GPa and 0.6 MPa, respectively. By considering the elastic bending of graphene sheets and buckle folding of pore walls, we develop a quantitative origami model that describes the stress-strain behavior of the aerogel. In addition, we analyze the mechanical oscillations of the graphene aerogel, observing superfast vibration damping within a time scale of 50–250 ns. Our study demonstrates the unusual coexistence of superelasticity and superfast damping within a cellular material with atomically thin pore walls, a phenomenon that does not occur in bulk elastic materials described by Hook’s law.

High-Temperature Fire Resistance and Self-Extinguishing Behavior of Cellular Graphene

“…We prepared the graphene aerogel by a threestep method using hydrothermal synthesis, freeze-drying, and high-temperature annealing, as reported previously. 37 In this method, micrometer-sized graphene oxide flakes were chemically reduced and assembled into a 3D porous aerogel structure, resulting in a mechanically robust yet flexible 3D covalent network of cross-linked graphene. The final hightemperature annealing at 1300 °C removed all oxygen defects from the graphene aerogels, providing a key step for the preparation of high-crystal quality graphene aerogels.…”

“…36 Interestingly, arranging graphene in a three-dimensional (3D) porous structure can combine both the important virtues of 2D graphene and low thermal conductivity in a single material. 3D graphene structures in the form of foams, sponges, and aerogels have demonstrated high mechanical strength, 37 flexibility, 38 electrical conductivity, 39 and oxidation stability between 500 and 705 °C, 40 yet extremely low thermal conductivity. 41 Although there have been a few attempts that involved fire-resistance testing of graphene aerogels, 42−44 little is known about the actual fire-retardant ability and fire resistance of high-quality 3D graphene.…”

Construction and application of carbon aerogels in microwave absorption

“…Some studies reveal that GO aerogel annealed at a graphitization temperature can lead to C–C covalent crosslinking between graphene sheets. 67 It is anticipated that the broken C–O bonds under a high annealing temperature transform to C–C bonds at adjacent graphene layers in the pyrolytic process. Note that the crosslinking molecules can influence the properties of GO aerogels in terms of mechanical strength and thermal conductivity.…”

A review on elastic graphene aerogels: Design, preparation, and applications

“…13 These derivatives have attracted great attention to prepare graphene-based aerogels because they not only inherit the unique properties of graphene but also show easy processability. 14 As one of the most important graphene macroassembly materials, graphene aerogels have many unique properties, such as ultralow density, 15 super-elasticity, 16 high specific surface area, 17 and excellent thermal stability. 18 They have attracted great interest in the past decades and shown great potential in high-performance pressure sensors, 19 energy storage, 20 contaminates absorbents/adsorbents, [21][22][23][24] thermal or acoustic insulators, 25 and electromagnetic wave functional materials.…”