NSF Award
2301838
When materials are stretched in one direction, it is typical that the dimensions in the other directions tend to decrease. However, some advanced materials, known as auxetic materials, exhibit a cross-sectional expansion that is perpendicular to the force applied during stretching. Auxetic materials are currently used in applications such as body armor, packing materials, knee and elbow pads, and sponge mops. Graphene oxide membranes are identified with auxetic behavior, which make them excellent candidate for a wide range of promising separation and filtration applications in the biomedical, automobile, and defense industries, and for clean energy. However, there is still a limited understanding of the underlying mechanism in their auxetic behavior. In this Engineering Research Initiation (ERI) project, a series of experiments will be carried out to gain a deeper understanding of the structure of graphene oxide membranes that causes its auxetic behavior. This project will provide research experiences for undergraduate students at Union College, especially those from traditionally underrepresented backgrounds. These research experiences will prepare students for scientific and technical careers, and/or graduate studies in nanotechnology-based industries. In addition, the research will be integrated into Union’s mechanical engineering curriculum to improve engineering education. <br/><br/>The objectives of this project are two-fold: 1) to achieve a fundamental understanding of the auxetic behavior of graphene oxide membranes by conducting experiments based on two hypotheses - the “wrinkle” and/or the “auxetic framework” are responsible for the behavior, and 2) to investigate how negative Poisson ratio customization affects the mechanical properties, stability, permeability, and potential applications of the membranes. Specifically, this experimental research will explore the relationship between the negative Poisson ratio and the size, orientation, and deformation of wrinkles, as per the "wrinkle" hypothesis. It will also investigate the correlation between the negative Poisson ratio and the oxygen/carbon atomic ratio of the "auxetic framework" hypothesis. By combining experimental studies and dynamic analyses, this project aims to not only identify the structural basis of graphene oxide membrane's auxetic behavior but also devise techniques for customizing this behavior to address a range of engineering challenges. This research project is also expected to lay the groundwork for the PI’s future research endeavors in the short and long term.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
