UNS: Rapid synthesis of ordered mesoporous materials through microwave processing of cooperatively assembled composites

介孔材料（2- 50nm孔径）广泛应用于催化、药物输送、能量储存和发电等众多领域。在大多数情况下，这些孔的连通性和大小对它们的性能至关重要。模板化的合成方法提供了一种方法来控制这两个属性。这些材料的典型直接合成方案包括嵌段共聚物或表面活性剂与功能前体（如溶胶凝胶纳米颗粒（NPs）或晶体NPs）的组装。在许多情况下，这些材料的高效制造仍然具有挑战性，特别是在复杂的过渡金属氧化物方面。即使是普通硅酸盐SBA-15的合成，标准过程也包括48小时的水热合成和550℃下5小时的煅烧（外加3小时的加热和冷却）。这些漫长的制造过程和能源密集型的煅烧过程是材料多样性和商业创新的重大限制。利用微波反应器可以将介孔硅酸盐的合成时间从几天缩短到几小时。随着微波技术在控制功率输出方面的进步，有序介孔二氧化硅的完整合成，包括模板降解，可以在几个小时内完成，而不是几天。但是，关于如何合理地选择前体和模板用于微波反应，从而能够在单一步骤中直接制造高功能有序介孔材料的信息有限。在这里，PI的目的是研究微波方法合成各种介孔材料的效用，包括金属碳酸盐和氧化物。该项目将阐明自组装有序介孔材料的形态如何受到模板和前体选择的影响，并展示微波处理如何使传统方法无法实现的混合金属氧化物纳米颗粒的形成。PI假设：(1)嵌段共聚物模板的热稳定性对介孔材料的最终结构至关重要，(2)高通量筛选将使鉴定可以（不）获得有序介孔结构的组合物，(3)微波处理将使合成无法通过传统途径获得的组合物，(4)卷对卷加工为快速和可扩展地制造这些材料提供了连续的途径。为了验证这些假设，PI将利用一系列系统的嵌段共聚物和金属硝酸盐-柠檬酸盐（Fe, Co， Ni和Mn）化学作为金属氧化物的前体。利用傅里叶变换红外光谱（FTIR）和椭偏仪检测金属硝酸盐转化为金属氧化物和聚合物模板的降解。反应动力学将作为微波功率的函数进行检验，并与传统的热方法进行对比。通过小角度x射线散射、原子力显微镜和x射线衍射，化学转变将与结构相关，以提供原子晶体结构和自组装纳米结构的信息。最后，将研究这些材料的电化学性能，以了解结构如何影响基于这些自组装材料的电池和超级电容器的性能。更广泛的影响可持续、廉价的能源是一个重大挑战。通过控制材料的形态、孔隙度和界面修饰，可以显著提高材料的发电（太阳能电池）和存储（电池和超级电容器）性能。通过这个项目获得的理解可以为改善这些材料的性能提供指导，这些材料可以用于这些应用，这可以帮助美国实现能源独立。更广泛的教育影响将涉及代表性不足的本科生的参与。与阿克伦全球聚合物学院和圣文森特圣玛丽高中的合作伙伴关系将包括教师和高中生进行研究并向广泛的K-12学生传播，其中参与研究的高中生将通过参加科学博览会竞赛向其他K-12学生和家长传播。拓展工作将包括研究生，因此他们将有机会在提高整体科学素养所需的较低技术水平上进行演讲。

1510612-VogtMesoporous (2-50 nm pore size) materials are widely used in numerous applications from catalysis to drug delivery to energy storage and generation. In most of these cases, the connectivity and size of these pores are critical to their performance. Templated synthetic methods provide one route to control both of these properties. The typical direct synthesis scheme for these materials involves the assembly of block copolymers or surfactants with functional precursors such as sol gel nanoparticles (NPs) or crystalline NPs. The efficient fabrication of these materials remains challenging in many cases, especially with regards to complex transition metal oxides. Even for the synthesis of a common silicate, SBA-15, the standard process involves 48 hours of hydrothermal synthesis and calcination at 550 °C for 5 hours (with an additional 3 hours for heating and cooling). These lengthy fabrication processes and energy intensive calcination processes are significant limitations to material diversity and commercial innovations. Using microwave reactors can reduce the synthesis time for mesoporous silicates from days to hours. With the advances in microwave technology for controlling power output, the full synthesis of ordered mesoporous silicas, including template degradation, can be performed in a single step in a few hours instead of days. But there is limited information on how to rationally select precursors and templates for use in microwave reactions that enable the direct fabrication of highly functional ordered mesoporous materials in a single step. Here the PI aims to investigate the utility of microwave methods for the synthesis of a diverse class of mesoporous materials including metal carbonates and oxides.Intellectual MeritThis project will elucidate how the morphology of self-assembled ordered mesoporous materials is impacted by the template and precursor selection and show how microwave processing enables the formation of mixed metal oxide nanoparticles that are not possible using conventional methods. The PI hypothesizes that (1) the thermal stability of the block copolymer template is critical to the final structure of the mesoporous material, (2) high throughput screening will enable identification of compositions where ordered mesoporous structure can(not) be obtained, (3) microwave processing will enable synthesis of compositions not accessible by conventional paths, and (4) roll-to-roll processing provides a continuous route to the rapid and scalable fabrication of these materials. To test these hypotheses, the PI will utilize a systematic series of block copolymers and metal nitrate-citrate (Fe, Co, Ni, and Mn) chemistry for precursors to the metal oxides. The conversion of the metal nitrate to metal oxide and the degradation of the polymer template will be examined using Fourier transform infrared spectroscopy (FTIR) and ellipsometry. The reaction kinetics will be examined as a function of microwave power and contrasted against conventional thermal methods. The chemical transformations will be correlated with the structure as elucidated by small angle x-ray scattering, atomic force microscopy, and x-ray diffraction to provide information on both the atomic crystal structure and the self-assembled nanostructure. Finally the electrochemical properties of these materials will be examined to understand how the structure impacts performance for batteries and supercapacitors based on these self-assembled materials.Broader ImpactSustainable, cheap energy is a significant challenge. Energy generation (solar cells) and storage (batteries and supercapacitors) properties can be significantly enhanced by exercising control over morphology, porosity, and interfacial modifications. The understanding garnered through this project could provide guidelines for improving the properties of these materials that could be utilized in these applications, which could help the US toward energy independence. The broader educational impact will involve participation of underrepresented undergraduate students. Partnerships with the Akron Global Polymer Academy and St. Vincent St. Mary's high school will include teachers and high school students in both research and dissemination to a broad audience of K-12 students, whereby high school students involved in the research will disseminate to other K-12 students and parents through participation in Science Fair competitions. The outreach efforts will include graduate students who will thus have an opportunity to present at less technical levels necessary for improving overall science literacy.