CAREER:Asymmetric Functionalization of 2-D Nanomaterials for Tailored Assemblies

在自然界和合成世界中，纳米级的颗粒材料在满足广泛的社会需求方面发挥着重要作用，从收集太阳能到使药物更有效，再到防止船舶底部的藤壶生长。因此，控制纳米颗粒如何组织成更大的结构可能会导致这些领域的重大进展。这个CAREER项目的研究重点是开发一种全新的定制纳米材料，并将它们组装成明确的几何形状。具体来说，只有几个原子厚的纳米片（氧化石墨烯）将在每面与具有不同性质（如正电荷和负电荷）的聚合物功能化。这些被称为Janus纳米片的独特结构，将具有即使是目前最先进的技术也无法达到的性能，并有可能改善涂料、药品、电池、润滑剂等的性能。此外，这项工作将帮助许多领域的研究人员了解纳米粒子的组织如何影响和决定它们的性质，从而改进它们。该项目将为下一代科学家和工程师提供跨学科培训，并通过动手演示让小学生参与科学。PI将指导高中、本科、研究生阶段的研究人员，为小学生开发亲水性和疏水性的课外互动课程，并通过为科学家提供的专业发展课程，为大学生的学术生涯做好准备。本研究的目标是开发和评估一类新型材料，用于控制纳米颗粒在组装中的空间和时间组织，作为合理设计和优化形式，功能和应用的途径。为此，将利用不同聚合物对氧化石墨烯的两个面进行不对称功能化，合成Janus氧化石墨烯纳米片。这些Janus GO纳米片的功能可以定制，以提供独特且定义良好的混合和响应组件。将利用三种特定的系统来展示这些新材料的性能：1)Janus氧化石墨烯纳米片与相分离聚合物功能化，在聚合物宿主体内以确定的方向组织，以制备具有定向导电性，机械强度和气体阻隔性能的复合薄膜；2)聚合物功能化的Janus氧化石墨烯纳米片可以与纳米颗粒结合，组装成明确的、高阶的、与无机纳米颗粒混合的组装体，以改善电荷传输、催化和能量储存；3) Janus氧化石墨烯纳米片与刺激响应聚合物功能化，以响应的方式可逆地滚动和皱化血小板，以动态控制气体吸附和电导率。这项工作的关键成果将提供控制纳米颗粒组件结构-性能关系的基本原理，从而实现技术应用的转型进步。这项工作还将提供一个框架，在此框架内对高中、本科和研究生阶段的未来科学家进行技术培训，并通过实践课程吸引小学生对科学的兴趣。此外，通过凯斯西储大学的CAREER项目，将为大四本科生和早期研究生开发专业发展课程，帮助学生获得在学术之外取得成功所需的职业技能。

PART 1: NON-TECHNICAL SUMMARYIn both nature and the synthetic world, particulate materials on the nanoscale play an important role in meeting a wide range of societal needs, from harvesting solar energy to making medicine more efficient to preventing barnacle growth on the underside of ships. As such, controlling how nanoparticles organize into larger structures could lead to major advances in these areas. The research focus of this CAREER project is to develop an entirely new class of tailored nanomaterials and to assemble them into well defined geometries. Specifically, nanosheets that are only a few atoms thick (graphene oxide) will be functionalized on each face with polymers that have different properties (such as positive and negative charges). These unique structures, called Janus nanosheets, will have properties that are not currently accessible with even current state-of-the art technology and have potential to improve the properties of coatings, medicines, batteries, lubricants, etc. Moreover, this work will help researchers across many fields understand how nanoparticle organization influences and dictates properties so they can be improved. This project will afford interdisciplinary training for the next generation of scientists and engineers, as well as engage elementary school students in science through hands-on demonstrations. The PI will mentor researchers at the high school, undergraduate, and graduate levels of their education, develop an after-school interactive class on hydrophilicity and hydrophobicity for elementary school students, and prepare college students for careers beyond academia through a professional development course for scientists. PART 2: TECHNICAL SUMMARYThe goal of this research is to develop and evaluate a new class of materials for the controlled spatial and temporal organization of nanoparticles in assemblies, as a route to rationally design and optimize form, function, and application. To this end, Janus graphene oxide (GO) nanosheets will be synthesized by the asymmetric functionalization of the two faces of GO with different polymers. The functionality of these Janus GO nanosheets can be tailored to give unique and well-defined hybrid and responsive assemblies. Three specific systems will be exploited to show the properties of these novel materials: 1) Janus GO nanosheets functionalized with phase separating polymers for organization in a defined direction within a polymer host to prepare composite films with directional conductivity, mechanical strength, and gas barrier properties; 2) Janus GO nanosheets functionalized with polymers that can bind to nanoparticles for assembly into well-defined, higher order, and hybrid assemblies with inorganic nanoparticles to improve charge transport, catalysis, and energy storage; and 3) Janus GO nanosheets functionalized with stimuli responsive polymers to reversibly scroll and wrinkle platelets in a responsive manner for dynamic control of gas adsorption and conductivity. The key outcomes of this work will provide the fundamental principles governing structure-property relationships of nanoparticle assemblies such that transformational advances in technological applications can be realized. This work will also provide a framework within which to technically train future scientists at the high school, undergraduate, and graduate levels, as well as engage the interest of elementary students in science through hands-on lessons. Moreover, through this CAREER project at Case Western Reserve University, a professional development course for senior undergraduate and early graduate students will be developed, helping students attain career skills needed for success beyond academia.