EAGER: Intrinsically Ferromagnetic Functional Cellulose Nanocrystals in Confinement

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Non-Technical AbstractNano-structured cellulose or "nanocellulose" is readily produced through the breakdown of cellulose fibers, which are ubiquitous in our surroundings. One form of nanocellulose, namely, cellulose nanocrystals (CNCs), are high aspect ratio, highly crystalline materials, whose mechanical properties have made them attractive candidates for a wide range of applications including polymer composites and personal care products. The high aspect ratio of CNCs imparts them with the ability to self-assemble into liquid crystalline (LC) phases which provide opportunities for the development of new sensors and optical technologies. This proposal explores the design and development of a class of functionalized CNCs, namely CNCs uniformly functionalized with earth abundant magnetic materials which will lead to the development of ferromagnetic alternatives. Low-cost, ferromagnetic materials based upon sustainable bio-derived materials could transform the world in which we live, creating opportunities for new optical devices that could be manipulated in the presence of magnetic fields, impacting technologies ranging from sensors to optical signaling and transmission. The proposed research provides opportunities for the integration of research and education in technologies of societal significance. In addition, students engaged in the program will be exposed to a multidisciplinary experience at the intersection of chemical engineering, materials science, materials chemistry and materials physics. The student participants will be cross-trained and where necessary will further expand their knowledge and experience through relevant additional collaborations.Technical AbstractThe propensity of cellulose nanocrystals (CNCs) to organize into liquid crystalline structures offers opportunities for the design of entirely new classes of sustainable materials that exhibit phenomena that may enable new classes of optical devices. Functional CNCs, in particular, offer opportunities for creating not only new classes of optical devices, but also magneto-optical devices. This project will explore the design of functionalized, intrinsically magnetic CNCs whose structure could be influenced by the presence of electrical and/or magnetic fields. It is proposed that a thin conformal layer of metals such as Ni, Cr, and Fe on the surface of the biomaterial will lead to creation of a cholesteric phase, which will provide a demonstration of an ordered fluid possessing spontaneous magnetization in the absence of an external magnetic field. Such a discovery will create entirely new research directions and opportunities for technology development. In an effort to understand and exploit the range of opportunities, ferromagnetic cholesteric liquid crystals will be created and the coupling between the magnetic moment and director of the chiral nematic phase will be investigated. In addition, the self-assembly of the functional CNCs in confined geometries, specifically spherical and cylindrical geometries will be interrogated. These studies will be combined with investigations into confinement of the liquid crystalline phase in thermoresponsive, spherical microgel particles. The proposed investigation will afford new, sustainable advanced optical technologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.