Study On Interlayer Mechanical Behaviors Of Graphene Oxide

As an ideal pearl-like layer structure assembly material,Graphene Oxide(GO)is highly sensitive to environmental humidity,which will significantly affect the interlayer shear performance of GO.In addition,one of the main methods to synthesize ultra-thin two-dimensional nano-metal materials is to grow them between GO thin films.It has been observed that the interlayer interaction of GO has great influence on its shear properties and metal growth.In view of the limitations of current experimental research in micro-nano scale,it is difficult to measure the quantitative relationship between some important parameters,and it is even more difficult to reveal the interaction mechanism of these factors.In this paper,the method of continuous mechanics theory and molecular dynamics(MD)simulation are adopted to study the influence of interlayer interaction of GO on its interlayer shear properties,and the influence of water content is further revealed and compared with the experimental results.Furthermore,the growth behavior of metal under GO interlayer confinement is discussed.The main research contents are as follows:(1)The influence of oxidation concentration on interlayer shear properties of rigid GO was studied by combining continuous mechanics theory with MD,the dependence of interlayer shear performance of GO on interlayer adhesion energy was explained.The results show that the increase of oxidation concentration will enhance the interlayer adhesion energy of GO,thus improving the interlayer shear strength.An optimal functional group concentration can be obtained for a GO with limited size,where the shear enhancement of GO will reach saturation.Good agreement can be achieved for the interlayer energy in theoretical models and MD simulations.The research put forward a simple numerical method for calculating the interlayer adhesion energy of GO,which verified with MD results and ensured the accuracy of the conclusion.Finally,based on this theory,MD simulation of interlayer shear performance of flexible GO was carried out.(2)MD simulation is used to analyze the influence of interlayer water content of GO on its shear behavior.The effects of oxidation concentration and functional group ratio on the interlayer shear strength of GO were comprehensively studied under different humidity environments.The results show that the interlayer shear performance of GO increases with the water content,and decreases with the further increase of water content after the optimum value is reached.And when the water content between GO layers is constant,the higher the oxidation concentration,the stronger the interlayer shear performance.In addition,hydroxyl groups are more conducive to the formation of hydrogen bonds between GO layers.Then,the accuracy of simulation results is further verified by frictional-wear experimental analysis.The experimental results show that reasonable control of environmental humidity can effectively increase the shear capacity between GO layers.(3)MD simulation is used to discuss the growth of Cu in the two-dimensional confined environment between GO layers.The effects of temperature,oxidation concentration on GO surface and spacing between GO layers on its growth rate were analyzed in detail.The results show that in order to speed up the simulation process,prefabricated nucleation factors can promote metal growth,and its growth rate first increases and then decreases with the increase of temperature.In addition,the nano-confinement environment affected the growth process of Cu grains,and the functional groups on the surface of GO caused a significant decrease in the growth process speed and final grain size of Cu grains.Furthermore,the higher the surface oxidation concentration and the smaller the spacing between GO layers,the more obvious the inhibition effect is.A new numerical calculation method for interlayer adhesion energy of GO is provided in this paper.The interlayer shear performance of GO is analyzed by MD simulation,and the microscopic mechanism of the influence of water content on its shear behavior is further analyzed.In addition,the growth of Cu in nano-confined environment between GO layers is also studied.The research results have certain reference significance for guiding the optimization design of the properties of GO-based composite structures and the preparation of nano-thick metal sheets.