Nanoparticle Monolayer Membranes

非技术总结：纳米颗粒为设计先进的下一代材料提供了特殊的机会。 该项目研究了这种基于纳米颗粒的材料的极限，当它们的厚度减少到只有一个颗粒时。 在这个极限下，单层（单层）紧密堆积的纳米颗粒联合收割机结合了极高的柔韧性和显著的强度。 该研究利用这些理想的机械性能来开发纳米颗粒膜，用于覆盖波纹或多孔表面和新型涂层。高度一致的可渗透膜的可用性有可能开辟广泛的新应用，包括纳滤。该项目为将研究与培训和外联结合起来提供了一个自然平台。它将培训一名博士后和一名研究生掌握重要的纳米科学知识，并在夏季向本科生介绍前沿科学。该项目将与一家大型科学博物馆合作，开发和原型化小规模的实践活动，用于向公众展示和演示。技术概要：该项目的重点是一类新的超薄膜，由单层紧密堆积的金属纳米颗粒制成，每个颗粒周围都有一层薄薄的短有机分子（配体），作为颗粒间的间隔物。 这些膜在一个单一的处理步骤中从溶液自组装到固体基底上，并且可以将自己覆盖在数百到数千个纳米颗粒宽的开孔上。由此产生的独立膜可以通过离子束和电子束切割和操纵，并且它们可以卷成管状结构。单层膜使得研究纳米级构建块的大型组件的材料特性而不受衬底的干扰成为可能，并且同时允许通过一系列探针（例如电子或扫描探针显微镜）直接实验访问单个构建块本身。该研究包括三个密切相关的实验工作，调查膜的机械行为的不同方面。第一个调查的弹性响应的中空管状结构形成的卷起的膜。其目标是确定大弯曲刚度的来源，该刚度超过基于标准连续弹性的预测高达两个数量级。第二个研究的机械响应的制度超越弹性变形和调查的细节，当地的颗粒分子的安排如何影响发病的屈服和断裂的平膜以及管状结构。第三个探讨了纳米粒子膜在新的应用中的使用，例如等离子体放大的表面特征的“收缩包装”和纳米过滤的多孔基底的涂层。

NON-TECHNICAL SUMMARY:Nanoparticles offer special opportunities for the design of advanced, next-generation materials. This project investigates the ultimate limit of such nanoparticle-based materials, when their thickness is reduced to that of just one particle. In this limit, single layers (monolayers) of closely packed nanoparticles combine extreme flexibility with remarkable strength. The research exploits these desirable mechanical properties to develop nanoparticle membranes for covering corrugated or porous surfaces and for novel coatings. The availability of highly conforming, ultrathin membranes has the potential to open up a wide range of new applications, including in nanofiltration. The project provides a natural platform for integrating research with training and outreach. It will train one postdoc and one graduate student in vital nanoscience know-how, and during the summer months introduce undergraduates to forefront science. In collaboration with a major science museum, the project will develop and prototype small-scale, hands-on activities for exhibits and demonstrations to the general public.TECHNICAL SUMMARY:This project focuses on a new class of ultra-thin membranes, fabricated from single layers of close-packed metallic nanoparticles, each particle surrounded by a thin coat of short organic molecules (ligands) that act as inter-particle spacers. The membranes are self-assembled in a single processing step from solution onto a solid substrate and can drape themselves over open holes that are hundreds to thousands of nanoparticles wide. The resulting freestanding membranes can be cut and manipulated by ion and electron beams, and they can be rolled up into tubular structures. Monolayer membranes make it possible to investigate the material properties of large assemblies of nanoscale building blocks without interference from a substrate, and at the same time allow for direct experimental access, via a range of probes such as electron or scanning probe microscopies, to the individual building blocks themselves. The research consists of three closely related experimental efforts that investigate different aspects of the mechanical behavior of the membranes. The first investigates the elastic response of hollow tubular structures formed from rolled-up membranes. Its goal is to identify the origin of the large bending stiffness that exceeds predictions based on standard continuum elasticity by up to two orders of magnitude. The second studies the mechanical response in the regime beyond elastic deformation and investigates how details of the local particle-molecule arrangements affect the onset of yielding and fracture in flat membranes as well as tubular structures. The third explores the use of nanoparticle membranes in new applications such as "shrink-wrapping" of surface features for plasmonic amplification and coating of porous substrates for nanofiltration.