BRIGE - Liquid-phase nanotechnology: Dispersion, rheology, and applications of pristine graphene

1032330绿色单层石墨，又称石墨烯，近年来因其优异的力学、热学和电学性能，包括几种不寻常的量子效应的能力，成为一种革命性的新型纳米材料而备受关注。石墨烯作为新型多功能材料的基础显示出巨大的前景，包括场效应晶体管、柔性电子设备、透明薄膜、纳米复合填料和结构碳纤维。这些材料和设备中的许多都需要可扩展的液态加工。然而，这类材料的开发一直受到与每个加工步骤相关的基本科学挑战的阻碍：(1)由于石墨烯片材剥落和快速团聚而导致的难以分散，(2)填料与基质之间的界面粘附性差，(3)对批量加工，特别是关于石墨烯的流变性和微观结构的了解不足。以前的研究已经使用了化学修饰的石墨烯，其性能远远低于原始石墨烯。该计划的目标是克服原始石墨烯材料的这些加工挑战。我们通过在石墨烯表面进行局部聚合，成功地进行了初步的原理验证实验，生成了包裹在聚合物纳米涂层中的原始石墨烯薄片。这项技术能够稳定地防止聚集，并将通过有效地结合到聚合物纳米复合材料中来展示。我们还在石墨烯流变学的新领域进行了创新研究，以实现可控的石墨烯加工。我们将实验流变学结果与盘状溶液的微观结构-流变学模型的模拟结果进行了比较。初步模拟结果显示，在建立对齐动力学模型方面，前景看好。智力优势：这一变革性的工程计划满足了石墨烯领域的三个关键科学挑战。产生了新的界面聚合技术，用于(1)生产以前从未获得的可再分散的原始石墨烯。此外，聚合物涂层允许(2)在纳米复合材料中对石墨烯和聚合物基质之间的界面进行精确的工程设计，以提高界面强度。这种方法具有开创性，因为它避免了与常用的氧化石墨工艺路线相关的性能退化。该计划还开创了石墨烯流变学的新领域，并通过实验和计算相结合的研究将流变性与石墨烯的排列和分散质量相关联。广泛的影响：尽管该计划侧重于石墨烯分散、界面化学和流变学的基础知识，但这些发现立即适用于需要进行大批量液相加工的基于石墨烯的材料和设备，包括电子设备、复合材料和薄膜。因此，这一跨学科项目将基础科学研究与实际工程应用相结合。这些发现将通过演讲和出版物在广泛范围内传播，并通过PI的功能材料课程在当地范围内传播。广泛参与：该计划寻求通过聘请本科生研究人员和一名高中教师来整合研究和教育，他们在工作的模拟方面的问题设计和可视化方面发挥核心作用。在这些研究工作的配合下，PI和高中教师将与TTU T-STEM中心合作，创建、评估、现场测试和传播纳米技术课程，用于9-12年级的STEM教育。该课程利用纳米技术中的科学和伦理挑战作为学生主导的研究项目和辩论的平台。本课程将强调学生的探究和主动学习，以便提供更深入的调查和学习，并在代表性不足的群体中提高对STEM领域的兴趣。这门课程通过强调纳米技术在环境责任和社会正义(例如，发展中国家的漏油清理、水净化)方面的潜力，在STEM领域创造了新的动机和热情；这些主题在STEM教育中往往被忽视，并将吸引更广泛的学生背景。

1032330GreenSingle-layer graphite, known as graphene, has taken center-stage as a revolutionary new nanomaterial in recent years due to its excellent mechanical, thermal, and electrical properties, including the capability for several unusual quantum effects. Graphene shows great promise as the basis for novel multifunctional materials, including field effect transistors, flexible electronics, transparent thin films, nanocomposite fillers, and structural carbon fiber. Many of these materials and devices require scalable, liquid-phase processing. However, development of such materials has been hampered by fundamental scientific challenges associated with each processing step (1) Difficult dispersion due to poor exfoliation and rapid re-aggregation of graphene sheets, (2) poor interfacial adhesion between filler and matrix, (3) poor understanding of bulk processing, particularly in regard to graphene rheology and microstructure. Prior studies have utilized chemically modified graphene with properties far inferior to pristine graphene. The goal of this program is to overcome these processing challenges for pristine graphene-based materials. We generate pristine graphene sheets encapsulated in a polymer nano-coating through localized polymerization on the graphene surface, as demonstrated through successful preliminary proof-of-principle experiments. This technique results in stabilization against aggregation and will be demonstrated by effective incorporation into polymer nanocomposites. We also create innovative studies in the novel field of graphene rheology in order to enable controlled graphene processing. We compare experimental rheometric results against simulations of the microstructure-rheology model for discotic solutions. Preliminary simulation results show promising results for modeling alignment dynamics.Intellectual merit: This transformative engineering plan meets three critical scientific challenges in the graphene community. Novel interfacial polymerization techniques are generated for (1) the production of re-dispersible, pristine graphene, which has never been attained before. Furthermore, polymer coating allows (2) the precise engineering of the interface between graphene and the polymer matrix in nanocomposites to increase interfacial strength. This approach is groundbreaking because it avoids the degraded properties associated with the commonly-used graphite oxide processing route. This program also pioneers the novel field of (3) graphene rheology and correlates rheological properties with graphene alignment and dispersion quality through a combination of experimental and computational studies.Broader impacts: Although this program focuses on the fundamentals of graphene dispersion, interfacial chemistry, and rheology, these findings have immediate application to the wide range of graphene-based materials and devices in need of bulk liquid-phase processing, including electronic devices, composites, and films. Thus, this interdisciplinary program combines fundamental scientific research with practical engineering applications. The findings will be disseminated on the broad scale through presentations and publications and on the local scale through the PI's functional materials course.Broadening Participation: The program seeks to integrate research and education by engaging undergraduate researchers and a high-school teacher with a central role in problem design and visualization for the simulation aspects of the work. In concert with these research efforts, the PI and the high school teacher will partner with the TTU T-STEM Center to create, evaluate, field-test, and disseminate nanotechnology curriculum for use in STEM education for grades 9-12. The curriculum uses both scientific and ethical challenges in nanotechnology as a platform for student-driven research projects and debates. This curriculum will emphasize student inquiry and active learning in order to provide deeper investigation and learning and generate increased interest in STEM fields among underrepresented groups. This curriculum creates new motivation and enthusiasm in STEM fields by emphasizing the potential for nanotechnology to be used for environmental responsibility and social justice (e.g., oil spill clean-up, water purification in developing countries); such topics are often neglected in STEM education and will engage a broader spectrum of student backgrounds.