Local Atomic-level Thermodynamic Probe for Nanoscience of 2D Membranes: Synthesis, NMR and Nanocalorimetry Study

用于二维膜纳米科学的局域原子级热力学探针：合成、核磁共振和纳米量热研究

• 批准号: 1809573
• 负责人: Leslie Allen
• 金额: $ 42.8万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1809573&HistoricalAwards=false
• 关键词: Local; Atomic; level; Thermodynamic; Probe

1. NON-TECHNICAL SUMMARYThrough this award, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, the PI develops a new characterization method for the nanoscience community. This new method is especially useful for research in ultra-thin membrane material and therefore might serve national interests in terms of health (understanding biological membranes) as well as by its usefulness for the nanoelectronics industry, which uses material (e.g. silicon and graphene) at extremely small nanometer size in both conventional as well as advanced devices. Currently, these devices are used in both national defense components as well as commercial devices such as next generation cell phones. The new technique is called "Local Atomic-Level Thermodynamic Probe" and it uses nuclear magnetic resonance, a technique which is similar in nature to the popular MRI medical instrument often used in hospitals to diagnose features within the human body, and combines it with nanocalorimetry, a rather novel technique that can measure materials properties such as melting temperatures of membrane layers that are only a few atoms thick. Most prominent among the Broader Impacts activities of this project is the aim to increase the Native American participation in education and research within the scientific community. To achieve this, outreach efforts focus on offering two-day sessions of a Summer Science Camp at the local community college in Browning, MT, the home of the Native American Blackfeet tribe. The theme of the camp uses hands-on experiments focusing on energy related projects. Activities will include (1) the use of voltmeter for electrical measurements; (2) assembly of Wind Turbine for LED lighting; (3) assembling kits that utilize solar energy; (4) hands-on calorimetry/solar/meter setup for heating water from solar energy. The camp will educate 60 high/middle school students. Another Broader Impact of this project is the enhancement of National Instrumentation Infrastructure with the invention of the nanocalorimetry technique which helps sustain the country's leadership role in the field of nanoscale thermal analysis by addressing a current gap in the breadth of advanced analytical techniques in the field of nanotechnology. 2. TECHNICAL SUMMARYThrough this award, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, the PI develops a new characterization method for the Nanoscience Community. This tool is a local atomic-level thermodynamic probe and consists of combining NMR and nanocalorimetry with new modeling methods (phenomenological thermodynamic models, DFT, MD and Monte Carlo). The project requires the synthesis of a special set of AgSCn-X 2D membranes, which act as the base material system for the development of the new technique. Two-dimensional (2D) membrane materials exhibit extraordinary properties that are universal in nature. They occur in living cells as well as in nanoelectronics. For example, graphene has remarkably high electron mobility and zero band gap while biological membranes form the outer layer structures of all living cells. Extraordinary changes in physical properties occur as the thickness of the membrane approaches the critical nanometer size range, e.g. size has a huge effect on the melting of lipid membranes in biological cell systems. Even changes of few degrees in temperature are critical in human body where the survival temperatures span over a very narrow range. Measuring the thermodynamic melting properties of single-layer membranes (~2 nm) and obtaining values for their melting point and enthalpy were only recently accomplished with the use of new nanocalorimetry technology. The latest discovery focuses on ultra-thin membranes with less than 7 carbons in the alkyl chains. Here the Gibbs-Thompson size-dependent model breaks down at a critical chain length at the transition between bulk and discrete sizes. In this small size regime, the shortcomings of nanocalorimetry and thermoanalysis become apparent when the thickness of membranes approaches their ultimate limit. At this small chain length, the melting point soars by 50 K and the melting enthalpy increases by ~400%. Nanocalorimetry has no depth perception; it only yields average thermodynamic values. NMR, on the other hand, can distinguish one atom from another. NMR has the unique capability to measure the local chemical environment of individual (type) atoms by monitoring the chemical shift. Combining these two techniques produces a powerful tool for Nanoscience investigations.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.

1. 通过这项由美国国家科学基金会材料研究部固态与材料化学项目资助的奖项，PI为纳米科学界开发了一种新的表征方法。这种新方法对超薄膜材料的研究特别有用，因此可能在健康（了解生物膜）方面符合国家利益，并对纳米电子工业有用，纳米电子工业在传统和先进设备中使用极小纳米尺寸的材料（例如硅和石墨烯）。目前，这些设备既用于国防部件，也用于下一代手机等商用设备。这项新技术被称为“局部原子级热力学探针”，它使用核磁共振技术，这种技术在性质上与医院常用的用于诊断人体特征的流行MRI医疗仪器相似，并将其与纳米量热法相结合，纳米量热法是一种相当新颖的技术，可以测量材料的特性，例如只有几个原子厚的膜层的熔化温度。在本项目的“更广泛影响”活动中，最突出的目标是增加美洲原住民参与科学界的教育和研究。为了实现这一目标，拓展工作的重点是在MT布朗宁当地社区大学提供为期两天的暑期科学营，这里是美国原住民黑脚部落的家园。夏令营的主题是以能源相关项目为重点的动手实验。活动将包括(1)使用电压表进行电气测量；(2)用于LED照明的风力发电机组装；（三）利用太阳能的组件组装；(4)手动量热仪/太阳能/仪表设置，用于太阳能加热水。该夏令营将教育60名中学生。该项目的另一个更广泛的影响是，纳米热测量技术的发明增强了国家仪器基础设施，通过解决当前纳米技术领域先进分析技术广度的差距，有助于维持该国在纳米级热分析领域的领导地位。2. 技术总结：通过这项由美国国家科学基金会材料研究部固态和材料化学项目资助的奖项，PI为纳米科学界开发了一种新的表征方法。该工具是局部原子级热力学探针，由核磁共振和纳米热测量与新的建模方法（现象学热力学模型，DFT， MD和蒙特卡罗）相结合组成。该项目需要合成一套特殊的AgSCn-X 2D膜，作为新技术开发的基础材料系统。二维（2D）膜材料表现出自然界普遍存在的非凡特性。它们既存在于活细胞中也存在于纳米电子学中。例如，石墨烯具有非常高的电子迁移率和零带隙，而生物膜形成了所有活细胞的外层结构。当膜的厚度接近临界纳米尺寸范围时，物理性质会发生非凡的变化，例如，在生物细胞系统中，尺寸对脂质膜的熔化有巨大的影响。对于生存温度范围很窄的人体来说，即使几度的温度变化也是至关重要的。测量单层膜（~2 nm）的热力学熔化性能，并获得其熔点和焓值是最近才使用新的纳米热测量技术完成的。最新的发现集中在烷基链中少于7个碳的超薄膜上。在这里，吉布斯-汤普森尺寸依赖模型在整体尺寸和离散尺寸之间过渡的临界链长处失效。在这种小尺寸体系中，当膜的厚度接近其极限时，纳米热分析法和热分析法的缺点就变得明显了。在这种小链长下，熔点提高了50 K，熔点焓提高了400%。纳米量热法没有深度感知；它只产生平均热力学值。另一方面，核磁共振可以区分不同的原子。核磁共振具有独特的能力，通过监测化学位移来测量单个（类型）原子的局部化学环境。这两种技术的结合为纳米科学研究提供了一个强大的工具。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。