Soler-Crespo Rafael A, Gao Wei, Xiao Penghao, Wei Xiaoding, Paci Jeffrey T, Henkelman Graeme, Espinosa Horacio D
Theoretical and Applied Mechanics Program, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Department of Mechanical Engineering, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
J Phys Chem Lett. 2016 Jul 21;7(14):2702-7. doi: 10.1021/acs.jpclett.6b01027. Epub 2016 Jul 1.
The mechanical properties of graphene oxide (GO) are of great importance for applications in materials engineering. Previous mechanochemical studies of GO typically focused on the influence of the degree of oxidation on the mechanical behavior. In this study, using density functional-based tight binding simulations, validated using density functional theory simulations, we reveal that the deformation and failure of GO are strongly dependent on the relative concentrations of epoxide (-O-) and hydroxyl (-OH) functional groups. Hydroxyl groups cause GO to behave as a brittle material; by contrast, epoxide groups enhance material ductility through a mechanically driven epoxide-to-ether functional group transformation. Moreover, with increasing epoxide group concentration, the strain to failure and toughness of GO significantly increases without sacrificing material strength and stiffness. These findings demonstrate that GO should be treated as a versatile, tunable material that may be engineered by controlling chemical composition, rather than as a single, archetypical material.
氧化石墨烯（GO）的力学性能对于材料工程应用至关重要。以往对GO的机械化学研究通常集中在氧化程度对力学行为的影响上。在本研究中，我们使用基于密度泛函的紧束缚模拟，并通过密度泛函理论模拟进行验证，揭示了GO的变形和失效强烈依赖于环氧基（-O-）和羟基（-OH）官能团的相对浓度。羟基使GO表现为脆性材料；相比之下，环氧基通过机械驱动的环氧基到醚基官能团转变增强了材料的延展性。此外，随着环氧基浓度的增加，GO的断裂应变和韧性显著增加，而不牺牲材料的强度和刚度。这些发现表明，GO应被视为一种通用的、可调节的材料，可以通过控制化学成分来进行设计，而不是作为一种单一的、典型的材料。
