Nanoscale Organic Hybrid Materials (NOHMs)

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TECHNICAL SUMMARY:Nanoscale organic hybrid materials (NOHMs) are star-branched organic polymers where the core of the star is an inorganic nanoparticle. By systematically changing the molecular weight, repeat unit chemistry, and grafting density of the star arms (corona) and/or the core particle size, shape, and mass distribution (e.g. hollow cores), the volume fraction of the inorganic component can be facilely adjusted to manipulate overall mechanical properties, conductivity, and structure of the hybrids. On one end of the spectrum are materials with high particle contents, which display properties similar to glasses, stiff waxes, and gels. At the opposite extreme are systems that spontaneously form particle-laden, solvent-free fluids characterized by a well-defined Newtonian flow regime and transport properties similar to simple liquids comprised of molecular building blocks. NOHMs are unique among hybrid nanomaterials because they form homogeneous liquids that are hybrids down to length-scales of the nanometer-sized building blocks. The proposed research uses a combination of experiments and theory to understand how geometric features of the NOHMs core and corona influence their equilibrium structure factor, ion transport properties, rheology, and interfacial behavior. The study also uses NOHMs as model systems for investigating soft glassy rheology, slow dynamics, and jamming in dense colloidal suspensions.NON-TECHNICAL SUMMARY: This project focuses on a recently discovered family of organic/inorganic hybrid materials which integrate - in a single platform - lightweight and low-cost features of plastics with mechanical strength and electrical stability of inorganic nanoparticles. Termed nanoscale organic hybrid materials (NOHMs), these hybrids show promise as electrolytes for next-generation, high-performance lithium batteries and as lightweight, puncture-resistant body armor for military and law-enforcement personnel. To take advantage of NOHMs in either application, it is essential to develop a comprehensive understanding of their structure and physical properties. The research proposed achieves this goal by using a combination of experimental and theoretical tools to establish relationships between properties of the materials and chemistry of their basic building blocks. The investigators propose to use these relationships to guide design of new NOHMs systems with explicit control of properties relevant for applications in lithium batteries and puncture-resistant coatings. They also propose to develop demonstration experiments based on applications of NOHMs in batteries and body armor that will be used to reach-out to high school students to increase interest in STEM careers.