CAREER: Mechanistic understanding of the nanoscale interactions of structurally tunable 3D assemblies of MXenes-polyelectrolytes

University Of South Carolina At Columbia, Columbia SC

Investigators

Abstract

Functional materials that predominantly absorb electromagnetic waves are desired for several applications relevant to the security and prosperity of the United States. These materials have a wide range of applications, including but not limited to preventing the interference of aircraft digital instruments, mitigating signal jamming, enhancing the performance of wireless devices, and safeguarding control of electronics for power grid systems. Most of the electromagnetic shields that are widely used at present rely mainly on reflecting the incident waves, which can result in secondary pollution. This Faculty Early Career Development project will combine experimental and computational studies to investigate how the molecular interactions between charge-containing polymers and two-dimensional carbides MXenes can be utilized to create functional materials with tunable electromagnetic wave absorption. This project will develop a science-based connection between the chemistry of charged macromolecules and MXenes and the mechanisms by which they interact, and form intricate, hierarchical nanoscale structures. In addition, this project will provide opportunities for high school, undergraduate, and graduate students, as well as STEM teachers, to engage in hands-on experiments and workshops. The project also involves curriculum development related to the synthesis, characterization, and application of hybrid functional materials based on nanoscale interactions. Regional research symposia on two-dimensional materials will also be organized to facilitate knowledge-sharing among the broader scientific community. The integration of MXenes and charged polymers within three-dimensional hybrid structures presents an enticing prospect for developing hybrid materials with adjustable mechanical and electrochemical properties. Nevertheless, creating such three-dimensional assemblies can prove difficult due to the complex surface chemistry of MXenes, which can result in uncontrolled interactions and, ultimately, aggregation. A key challenge in the field of MXene nanomaterials is gaining a fundamental understanding of these interactions and discovering methods to manipulate them effectively. This CAREER project addresses this challenge by integrating experimental and computational modeling through three interconnected research thrusts. The first thrust focuses on comprehending the nanoscale interactions between MXenes and polyelectrolytes, while the second thrust aims to exploit these interactions to direct the 3D bottom-up assembly. The third thrust involves the bottom-up structural modulation of electromagnetic wave absorption. The dynamics of assembly and the development of morphology and composition will be studied at multiple length scales. The regulation of morphology is accomplished by managing the conformation of the adsorbed polymer chains on MXene nanosheets, which controls the nanostructure of the MXene-polyelectrolyte heterointerface. The impact of various molecular characteristics of polyelectrolytes and MXenes, as well as hydrodynamic forces, on their interactions at heterointerfaces and the assembly of MXenes-polyelectrolyte into hybrid structures will be explored. This project will also demonstrate how controlling the interface nanostructure can lead to the creation of hybrid materials with improved microwave absorption, which arises from tunable electrical conductivity and interfacial polarization. The fundamental knowledge obtained from this research has the potential to inform the development of other MXene-based hybrids for applications in antimicrobial materials and water treatment. This project will integrate research, teaching, and outreach initiatives to advance scientific innovation while educating and inspiring a diverse, inclusive group of future STEM students and researchers. This project is jointly funded by the CBET Nanoscale Interactions Program and the Established Program to Stimulate Competitive Research (EPSCoR). 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.