SNM: Low-Cost, Large-Scale Nanomanufacturing of Superinsulating Aerogels and Lightweight, Mechanically-Strong Aerogels

SNM：低成本、大规模纳米制造超绝缘气凝胶和轻质、机械强度高的气凝胶

• 批准号: 1530603
• 负责人: Marc Hodes
• 金额: $ 149.93万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1530603&HistoricalAwards=false
• 关键词: SNM; Low; Cost; Large; Scale

Heating and cooling of buildings in the United States accounts for 15 percent of energy use and 32 percent of carbon dioxide emissions. Aerogels are low-density, superinsulating nanomaterials that can dramatically reduce these numbers but are expensive to manufacture. While the insulation market is about $40 billion, aerogels account for less than 1 percent of it. Fossil-fuel-based transportation accounts for another 27 percent of emissions. Mechanically-robust aerogels can be used as lighter weight replacements for plastics to reduce the weight of vehicles, improving fuel efficiency by 10 percent. During aerogel manufacturing, supercritical carbon dioxide-based extraction is commonly utilized to remove liquid from a gel while preserving the solid nanostructure of the gel skeleton. This process accounts for as much as 50 percent of manufacturing costs, requires copious amounts of carbon dioxide and energy and stifles throughput. This research award will provide a scientific foundation to enable development and piloting of fast, efficient drying processes that preserve the skeleton of aerogels. It will enable lower costs, scaling of quantities and dimensions and diversification of materials. Porous three-dimensional nanomaterials other than aerogels are pervasive across many fields; for example, artificial tissue scaffolds. Results generated from this research will be relevant to the manufacture of such other nano-scale materials and structures. The work plan includes development of a pre-college STEM curriculum and distribution of public-friendly content about nanotechnology through an online outreach portal.The enabling technical output is a model of mass transfer in supercritical carbon dioxide under aerogel drying conditions that captures the effects of fluid composition, compressibility and properties and, additionally, material microstructure and strain. This model will enable the determination of modulation of flow rates, temperatures and pressures, select solvents, order pore-fluid exchanges and formulate gels to develop and pilot inexpensive, fast drying processes that minimize macroscopic and nanoscopic damage to aerogels. The technical approach consists of five Tasks. (1) Measure drying kinetics as a function of process parameters to aid in model development and iteratively refine pilot-scale nanomanufacturing; (2) Measure densities of supercritical carbon dioxide-solvent systems and develop metrology to monitor drying; (3) Measure diffusion coefficients; (4) Measure volumetric strain states inside gels in situ as they are dried; and (5) Use small-angle X-ray scattering to elucidate effects of drying on and correlate stresses with morphostructural changes and identify materials for pilot testing. The fundamental nanomanufacturing principles will be applicable to a range of inorganic, polymeric and composite aerogels.

在美国，建筑物供暖和制冷消耗的能源占 15%，二氧化碳排放量占 32%。气凝胶是低密度、超绝缘纳米材料，可以大大减少这些数字，但制造成本昂贵。虽然绝热材料市场规模约为 400 亿美元，但气凝胶仅占其中不到 1%。另外 27% 的排放量来自化石燃料交通。机械强度高的气凝胶可用作重量更轻的塑料替代品，以减轻车辆的重量，从而将燃油效率提高 10%。在气凝胶制造过程中，通常采用超临界二氧化碳萃取来去除凝胶中的液体，同时保留凝胶骨架的固体纳米结构。这一过程占制造成本的 50% 之多，需要大量的二氧化碳和能源，并且抑制了生产量。该研究奖将为开发和试点快速、高效的干燥工艺提供科学基础，以保护气凝胶的骨架。它将实现更低的成本、数量和尺寸的扩展以及材料的多样化。除气凝胶外，多孔三维纳米材料广泛应用于许多领域。例如，人造组织支架。这项研究产生的结果将与其他纳米级材料和结构的制造相关。该工作计划包括开发大学预科 STEM 课程以及通过在线外展门户分发有关纳米技术的公众友好内容。支持的技术输出是气凝胶干燥条件下超临界二氧化碳中的传质模型，该模型捕捉了纳米技术的影响流体成分、压缩性和特性，以及材料微观结构和应变。该模型将能够确定流量、温度和压力的调节、选择溶剂、命令孔隙流体交换和配制凝胶，以开发和试验廉价、快速的干燥过程，从而最大限度地减少对气凝胶的宏观和纳米级损伤。该技术方法由五个任务组成。 (1) 测量干燥动力学作为工艺参数的函数，以帮助模型开发并迭代完善中试规模纳米制造； (2) 测量超临界二氧化碳-溶剂系统的密度并开发监测干燥的计量学； (3) 测量扩散系数； (4) 干燥时原位测量凝胶内部的体积应变状态； (5) 使用小角度 X 射线散射来阐明干燥对形态结构变化的影响并将应力与形态结构变化相关联，并确定用于中试测试的材料。基本的纳米制造原理将适用于一系列无机、聚合物和复合气凝胶。