EAGER: Intrinsically Ferromagnetic Functional Cellulose Nanocrystals in Confinement

非技术摘要纳米结构的纤维素或“纳米纤维素”很容易通过分解纤维素纤维而产生，而纤维素纤维在我们的环境中无处不在。纳米纤维素的一种形式，即纤维素纳米晶(CNCS)，是高纵横比、高度结晶的材料，其机械性能使其在包括聚合物复合材料和个人护理产品在内的广泛应用中具有吸引力。碳纳米管的高纵横比赋予了它们自组装成液晶(LC)相的能力，这为新的传感器和光学技术的发展提供了机会。该方案探索了一类功能化CNCS的设计和开发，即用富含地球的磁性材料均匀功能化的CNCS，这将导致铁磁替代品的发展。基于可持续生物衍生材料的低成本铁磁材料可以改变我们生活的世界，为可以在磁场存在的情况下操纵的新光学设备创造机会，影响从传感器到光信号和传输的各种技术。拟议的研究为在具有社会意义的技术领域整合研究和教育提供了机会。此外，参与该项目的学生将在化学工程、材料科学、材料化学和材料物理的交叉点接触到多学科体验。学生参与者将接受交叉培训，必要时将通过相关的额外合作进一步扩展他们的知识和经验。技术摘要纤维素纳米晶体(CNCs)组织成液晶结构的倾向为设计全新的可持续材料类别提供了机会，这些材料展示的现象可能使新类别的光学设备成为可能。尤其是功能CNCS，不仅为创造新的光学设备类别提供了机会，而且为创造磁光设备提供了机会。本项目将探索功能化、本征磁性CNCS的设计，其结构可能会受到电场和/或磁场的影响。研究表明，在生物材料表面形成一层薄的金属如镍、铬、铁等共形层将导致胆甾相的生成，这将证明有序流体在没有外加磁场的情况下具有自发磁化作用。这一发现将为技术发展创造全新的研究方向和机遇。为了理解和利用这些机会，我们将创造铁磁性胆甾相液晶，并研究手性向列相的磁矩和指向矢之间的耦合。此外，还将探讨功能碳纳米管在受限几何图形中的自组装，特别是球面和柱面几何图形。这些研究将与对热敏球形微凝胶颗粒中液晶相限制的研究相结合。拟议的调查将提供新的、可持续的先进光学技术。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.