Understanding the Auxetic Structure of Graphene Oxide

Graphene Oxide (GO) is a very unique material. Unlike conventional materials, GO has a Negative Poisson Ratio (NPR), which makes it an auxetic material. When an auxetic material is stretched under tension, it becomes thicker in the perpendicular direction to the applied force. This occurs due to the particular internal structure of auxetic materials and the way they deform when uniaxially loaded. GO’s internal structure is made up of microscopic sheets, assembled together to form Graphene Oxide membrane. The specific behavior of the GO membrane is dependent on the shape, size and connection of the GO sheets. Previous experimental studies have shown that GO has a Negative Poisson Ratio, but very few publications have examined the structure of the GO sheets to explain why it has a NPR. Graphene Oxide is a relatively accessible auxetic material that could have the potential to improve the performance, comfort, and safety of a wide range of products and technologies, especially in protection application. This project will add to the understanding of GO by observing the two dimensional structure of GO sheets. Plasma treated thermal oxide wafer samples were prepared with a droplet of GO solution. These samples were examined using an optic-microscope, which allowed for the ability to capture high quality images of the GO sheets. Once a large enough catalog of images is created, machine learning will be used to identify the basic geometry structure that most closely represents the structure of a “typical” GO sheet. That basic geometry will be used to assemble a 2 dimensional SOLIDWORKS model to understand the behavior and movement of GO. This isn’t a well established project due to limited literature available, but it is a first step into understanding the microscopic structure of GO. The project can only be successful if the image database of GO sheets are high quality and large enough to help build an accurate model. Thermal oxide wafers are used as the surface for the GO solution, allowing us to get high quality images of nanometer thick GO sheets underneath the optical microscope. With all these boxes checked off, the project will help grow the understanding of GO at the microscopic level and potentially help innovate future products and a wide range of applications.