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

主要吸收电磁波的功能材料对于与美国的安全和繁荣相关的若干应用是期望的。这些材料具有广泛的应用，包括但不限于防止飞机数字仪器的干扰，减轻信号干扰，增强无线设备的性能，以及保护电网系统的电子控制。目前广泛使用的电磁屏蔽大多数主要依靠反射入射波，这会导致二次污染。这个教师早期职业发展项目将联合收割机实验和计算研究相结合，以研究如何含电荷的聚合物和二维碳化物MXenes之间的分子相互作用可以用来创建功能材料与可调电磁波吸收。该项目将在带电大分子和MXene的化学性质与它们相互作用的机制之间建立一种基于科学的联系，并形成复杂的分层纳米级结构。此外，该项目将为高中，本科和研究生以及STEM教师提供参与动手实验和研讨会的机会。该项目还涉及与基于纳米级相互作用的混合功能材料的合成，表征和应用相关的课程开发。此外，还将组织关于二维材料的区域研究研讨会，以促进更广泛的科学界之间的知识共享。MXene和带电聚合物在三维杂化结构中的整合为开发具有可调节机械和电化学性能的杂化材料提供了诱人的前景。然而，由于MXene复杂的表面化学性质，创建这种三维组件可能会被证明是困难的，这可能导致不受控制的相互作用，并最终导致聚集。MXene纳米材料领域的一个关键挑战是对这些相互作用有一个基本的了解，并发现有效操纵它们的方法。这个CAREER项目通过三个相互关联的研究重点整合实验和计算建模来应对这一挑战。第一个重点是理解MXene和聚电解质之间的纳米级相互作用，而第二个重点旨在利用这些相互作用来指导3D自下而上的组装。第三个推力涉及电磁波吸收的自下而上的结构调制。将在多个长度尺度上研究组装的动力学以及形态和组成的发展。形态的调节是通过管理MXene纳米片上吸附的聚合物链的构象来实现的，其控制MXene-纳米片异质界面的纳米结构。将探讨聚电解质和MXenes的各种分子特性以及流体动力学对它们在异质界面的相互作用和MXenes-mxenes组装成混合结构的影响。该项目还将展示如何控制界面纳米结构可以导致创建具有改进的微波吸收的混合材料，这是由可调的电导率和界面极化引起的。从这项研究中获得的基础知识有可能为开发其他基于MXene的混合物用于抗菌材料和水处理提供信息。该项目将整合研究，教学和推广活动，以推动科学创新，同时教育和激励多元化，未来STEM学生和研究人员的包容性团体。该项目由CBET纳米尺度相互作用计划和刺激竞争性研究既定计划（EPSCoR）联合资助该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.