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

UNS：通过协同组装复合材料的微波处理快速合成有序介孔材料

• 批准号: 1510612
• 负责人: Yu Zhu
• 金额: $ 30万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1510612&HistoricalAwards=false
• 关键词: UNS; Rapid; synthesis; ordered; mesoporous

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.

1510612-Vogt 介孔（2-50 nm 孔径）材料广泛用于从催化到药物输送再到能量存储和发电的众多应用。在大多数情况下，这些孔隙的连通性和大小对其性能至关重要。模板化合成方法提供了一种控制这两种特性的途径。这些材料的典型直接合成方案涉及将嵌段共聚物或表面活性剂与功能性前体（例如溶胶凝胶纳米粒子（NP）或结晶纳米粒子）组装。在许多情况下，这些材料的高效制造仍然具有挑战性，特别是对于复杂的过渡金属氧化物。即使是合成常见的硅酸盐 SBA-15，标准工艺也需要 48 小时的水热合成和 550 °C 下的煅烧 5 小时（另外 3 小时用于加热和冷却）。这些冗长的制造过程和能源密集型煅烧过程严重限制了材料多样性和商业创新。使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。随着控制功率输出的微波技术的进步，有序介孔二氧化硅的完全合成，包括模板降解，可以在几个小时而不是几天内一步完成。但关于如何合理选择用于微波反应的前体和模板，从而能够一步直接制造高功能有序介孔材料，信息有限。在这里，PI 的目的是研究微波方法在合成各种介孔材料（包括金属碳酸盐和氧化物）中的实用性。智力价值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能够形成使用传统方法不可能实现的混合金属氧化物纳米颗粒。 PI 假设 (1) 嵌段共聚物模板的热稳定性对于介孔材料的最终结构至关重要，(2) 高通量筛选将能够识别无法获得有序介孔结构的组合物，(3) 微波处理将能够合成传统途径无法获得的组合物，(4) 卷对卷加工提供了一条连续途径，可快速、准确地获得有序介孔结构。 这些材料的可扩展制造。为了测试这些假设，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（铁、钴、镍和锰）化学作为金属氧化物的前体。金属硝酸盐向金属氧化物的转化以及聚合物模板的降解将使用傅里叶变换红外光谱（FTIR）和椭圆光度法进行检查。反应动力学将作为微波功率的函数进行检查，并与传统的热方法进行对比。化学转变将与通过小角度 X 射线散射、原子力显微镜和 X 射线衍射阐明的结构相关联，以提供有关原子晶体结构和自组装纳米结构的信息。最后，将检查这些材料的电化学特性，以了解其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。通过控制形态、孔隙率和界面改性，可以显着增强能量产生（太阳能电池）和存储（电池和超级电容器）性能。通过该项目获得的理解可以为改善这些应用中使用的材料的性能提供指导，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参与研究并向广大 K-12 学生传播，参与研究的高中生将通过参加 Science Fair 竞赛向其他 K-12 学生和家长传播研究成果。外展工作将包括研究生，因此他们将有机会以提高整体科学素养所需的较低技术水平进行演讲。