LEAPS-MPS: Harnessing materials from nature: from biomaterials to metal oxides

第一部分：人们普遍认为，自从第一批植物和动物出现在地球上以来，自然界一直在完善其材料。因此，大自然给了我们一些最好和最独特的材料的灵感，如壁虎脚，鲨鱼皮和荷叶。仿生材料试图通过模仿天然材料的结构来利用这数亿年的进化。不幸的是，天然材料通常很难或不可能在我们的实验室中复制，因为每种新的生物材料通常都需要一种新的、量身定制的策略来将其复制为人造材料。这种策略，如果存在的话，往往是相当复杂的，限制了可能的材料组成，使他们难以扩大规模。“碳复制”天然材料的过程将是一个完美的解决方案。该项目将研究利用化学将天然材料矿化成金属氧化物的过程。然后，这种矿化过程可以通过将天然材料的样品转化为具有相同结构但不同组成的金属氧化物样品来用于仿生材料的快速原型制作。它还可用于将农业和林业的生物质和生物废物原料转化为新的增值材料，用于催化，能量储存和转换，吸附，传感和光学应用。该项目还整合了一个全面的计划，以增加STEM中代表性不足的群体的参与，以及工业界和学术界代表性不足的群体的领导者和榜样的数量。该计划将高中和社区推广活动与高中，本科生和研究生的培训和指导相结合。第2部分：技术总结非水解溶胶-凝胶（NHSG）矿化展示了天然纤维素材料转化为金属氧化物的结构保留。然而，我们目前缺乏对固体材料如何完成这一过程的了解，以及它是否可以应用于其他天然材料。本研究提案的总体目标是了解NHSG矿化纤维素的机制及其与其他天然材料的相容性。核心假设是NHSG矿化与其他多糖和富氧聚合物相容，如果它们可以被溶剂溶胀并具有适当类型和量的氧基团。强调拟议研究的基本原理是，所产生的理解将解锁将天然材料转化为具有定制成分的金属氧化物的一般策略。PI计划通过追求以下具体目标来实现总体目标：（1）阐明纤维素材料的NHSG矿化机制和（2）阐明NHSG矿化与其他聚合物材料的相容性。为了完成具体目标#1，PI将使用精心设计的纤维素材料，通过能量色散X射线光谱法结合横截面扫描电子显微镜和元素图谱来研究转化过程。具体目标#2将通过测试NHSG矿化中具有广泛化学和结构特性的常见天然聚合物来完成，以了解聚合物材料实现有效转化的要求。该项目还将支持对研究生、本科生和高中生的培训。高中生将参加为期8周的暑期研究项目，在那里他们将进行研究并接受指导，使他们能够继续接受STEM教育。总体而言，该项目将支持至少一名妇女，一名代表性不足的少数民族学生和两名弱势学生参与STEM。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYIt is widely appreciated that nature has been perfecting its materials since the first plants and animals appeared on Earth. Thus, nature gives us inspiration for some of the best and most unique materials, such as gecko feet, shark skin, and lotus leaves. Biomimetic materials try to capitalize on these hundreds of millions of years of evolution by mimicking the structures of natural materials. Unfortunately, natural materials are often difficult or impossible to reproduce in our laboratories since each new biomaterial generally requires a new, tailored strategy to reproduce it as a man-made material. Such strategies, if exist, are often quite intricate, limiting the possible material compositions and making them difficult to scale up. A process for "carbon copying" natural materials would be a perfect solution. This project will study a process of mineralization of natural materials into metal oxides using chemistry. Such mineralization process can then be used for quick prototyping of biomimetic materials by converting samples of natural materials into metal oxide samples with the same structure but varied compositions. It can also be used to convert feedstock of biomass and biowaste from agricultural and forestry industries into new, value-added, materials for catalysis, energy storage and conversion, adsorption, sensing, and optical applications. The project also integrates a comprehensive plan for increasing participation of underrepresented groups in STEM and the numbers of leaders and role models from underrepresented groups in industry and academia. This plan combines high-school and community outreach activities with training and mentoring of high school, undergraduate, and graduate students.PART 2: TECHNICAL SUMMARYNon-hydrolytic sol-gel (NHSG) mineralization demonstrated conversion of natural cellulosic materials into metal oxides with structure retention. However, we currently lack the understanding of how this process is completed for solid materials and if it can be applied to other natural materials. The overall objective of this research proposal is to understand the mechanism of NHSG mineralization of cellulose and its compatibility with other natural materials. The central hypothesis is that NHSG mineralization is compatible with other polysaccharides and oxygen-rich polymers if they can be swelled by the solvent and have an appropriate type and amount of oxygen groups. The rationale that underlines the proposed research is that the generated understanding will unlock a general strategy for converting natural materials into metal oxides with tailored composition. PI plans to achieve the overall objective by pursuing the following specific objectives: (1) elucidate mechanism of NHSG mineralization for cellulosic materials and (2) elucidate compatibility of NHSG mineralization with other polymeric materials. To complete Specific Objective #1, PI will use carefully designed cellulose materials to study the conversion process with cross-sectional scanning electron microscopy coupled with elemental mapping via energy-dispersive X-ray spectroscopy. Specific Objective #2 will be completed by testing common natural polymers with broad range of chemical and structural properties in NHSG mineralization to understand requirements for polymeric materials to achieve effective conversion. The project will also support training of graduate, undergraduate, and high school students. High school students will be hosted for an 8-week summer research project where they will conduct research and receive mentoring to empower them to continue into STEM education. Overall, the project will support participation of at least one woman, one underrepresented minority student, and two disadvantaged students in STEM.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.