Functional Block Copolymers as Guides for NanoparticleAssembly: Preparation of Cobalt Nanoparticles from Alkyne-Functional Polymers

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TECHNICAL SUMMARY:Controlling the organization of metallic nanoparticles in three-dimensional space is an important goal for the development of nanometer-scale materials for applications including energy storage, light harvesting, catalysis, and memory storage. One potential route to this goal involves the exploitation of the tendency for block copolymers to undergo micro-phase separation in which each polymer block occupies well-defined spatial regions in the bulk material. Development of such hybrid materials requires an understanding of the synthesis and behavior of specific functional block copolymers. Ongoing efforts to control ordering and structure of cobalt nanoparticles through controlled synthesis of alkyne-functional polymers will be continued through this grant. The fundamental questions to be addressed by this research relate to understanding how control over structure of alkyne-functional block copolymers can provide control over size and shape of cobalt (and other) nanoparticles. Understanding these relationships will guide subsequent efforts to prepare polymer-inorganic hybrids containing multiple types of nanoparticles.These issues will be approached through the construction of libraries of selected alkyne-functional block copolymers followed by an examination of their phase behavior as a function of polymer size, composition, and cobalt loading. The effects of these variables on the magnetic properties of the resulting materials and on the nature of the polymer-cobalt interface will subsequently be examined. The physical crosslinks that the alkyne-functional polymers in these systems form under mild conditions will be exploited to control the degree of nanoparticle surface functionalization. This research will further the understanding of how metallic nanoparticles can be incorporated into larger assemblies with the aid of multi-block copolymers and will facilitate future application of these materials. NON-TECHNICAL SUMMARY:This project aims to increase the understanding of how specifically-designed organic polymer molecules can be used to control how nanometer-sized metal particles come together to form larger materials that show useful magnetic, electronic, and optical properties. Such designed materials have great potential in a range of applications including solar cells, batteries, catalysts, and memory storage devices. Researchers at the undergraduate, graduate, and post-doctoral levels will be involved in this research and will participate in the communication of their research to the general public at scientific meetings at the local, regional, and national levels, including the New England Polymer Chemistry Workshop, an informal series of regional meetings designed to give graduate students the opportunity to present their research. The PI will also work through the Summer Enrichment at Dartmouth (SEAD) program to inform students from under-resourced urban and rural high schools about opportunities in scientific research at the college and graduate levels.