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

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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.