IDR: Emergent Assembly & Patterning of Dynamic Catalytic Motor Systems

催化马达是一类将化学能转化为机械能的新型纳米和微尺度粒子和组件。宾夕法尼亚州立大学化学工程和化学系的pi Darrell Velegol和Ayusman Sen之间的现有合作，在催化马达领域的初步实验的基础上提出了这项工作。这些催化马达是多相纳米颗粒，催化反应导致它们在溶液中运动。这些运动可以受到化学梯度和光的影响。单独的马达以几十微米/秒的速度在随机方向上运动，研究小组已经研究并建立了传输物理模型。总的来说，马达的复杂行为类似于趋化性、趋光性，甚至是通常只在生物系统中看到的捕食者-猎物现象。这显然是第一次在生命系统之外观察到这种现象。由于催化反应的持续能量输入，这些驱动系统的运行远离平衡。因此，可以在粒子集合内形成分层或动态模式。pi已经做了足够的前期工作来证明他们确实观察到了非常有趣的粒子集体运动。这些运动有多种不同的类型，在构建静态和动态纳米结构方面都有潜在的用途。提出的工作利用新的纳米粒子合成和粒子运动的测量，结合运动的动力学建模，以预测行为。pi表示，总体目标是建立在纳米和微米尺度上操纵能量和信息的原则，以创造材料的模式，从而引领技术的发展，其能力甚至可能与生物的能力相媲美。这使得pi可以提出这样的问题：我们可以设计出复杂模式产生的粒子系统吗？我们可以使用模式来快速评估单个催化剂的质量/可变性吗？我们能否对随时间动态变化的材料进行设计？Velegol和Sen在将他们的观察结果与微生物系统中观察到的运动和集体行为类型联系起来方面做得很好，这增加了该项目的吸引力。由于这项工作具有很高的视觉冲击力和重要的基础内容，该主题提供了强大的扩展机会，包括研究生教育，本科生参与，以及参与宾夕法尼亚州立大学的向上数学和科学项目，该项目扩展到城市学区。本科生似乎有非常积极的研究经历，这导致他们中的一些人参加了全国最好的研究生课程。pi表现出了出色的合作能力，并鼓励他们的研究小组合作。这项工作将在主要的材料、化学和物理期刊上广泛发表，并在主要的科学会议上发表。跨学科研究。该项目结合了尖端胶体化学（包括合成、制造、功能化和催化）和尖端胶体物理学（包括自动电动现象和模拟）。这项研究也影响到研究生和本科生，因为它需要高度多学科的工作。学生将学习化学、化学工程和纳米制造领域的尖端技术，以及动态系统的建模策略。Velegol和Sen提出了一个项目，该项目体现了现代先进基础科学项目的跨学科性质。

1014673VelegolCatalytic motors are a novel class of nano- and microscale particles and assemblies that convert chemical energy to mechanical energy. The proposed work builds on the initial experimentation in the area of catalytic motors an existing collaboration between the PIs Darrell Velegol and Ayusman Sen in the Departments of Chemical Engineering and Chemistry at The Pennsylvania State University. These catalytic motors are multiphase nanoparticles that catalyze reactions resulting in their motion through solution. These motions can be influenced by chemical gradients and by light. Individually the motors move in a random direction at speeds of tens of microns/sec, and the transport physics has been studied and modeled by the research groups. Collectively, the motors give complex behaviors similar to the chemotaxis, phototaxis, or even predator-prey phenomena normally seen only in biological systems. This is apparently the first observation of this phenomenon outside living systems. Because of the continuous input of energy due to the catalytic reaction, these are driven systems that operate far from equilibrium. Thus, hierarchical or dynamic pattern formation can result within the collection of particles. The PIs have done sufficient prior work to demonstrate that they do observe very interesting collective motion of the particles. These motions are of a variety of different types and are of potential use in building both static and dynamic nanostructures. The proposed work makes use of novel nanoparticle syntheses and measurements of particle motion, combined with electrokinetics modeling of the motion, in order to predict behavior.The PIs state the overarching goal is to establish principles for manipulating energy and information on the nano- and micron scales to create patterns of materials, leading toward technologies with capabilities perhaps even rivaling those of living things. This allows the PIs to pose questions such as: Can we design particle systems from which complex patterns emerge? Can we use patterns to quickly assess the quality/variability of individual catalysts? Can we pattern materials that change dynamically in time? Velegol and Sen have done a very nice job of relating their observations to types of motions and collective behaviors observed in microbial systems, which adds to the attractiveness of the project.Since the work has high visual impact as well as significant fundamental content, the subject provides powerful outreach opportunities including graduate student education, undergraduate participation, and involvement with the Upward Bound Math and Science program at Penn State, which does outreach to urban school districts. The undergraduates seem to have a very positive research experience and this has resulted in a number of them attending some of the best graduate programs in the country. The PIs have demonstrated excellent ability to work together and to encourage their research groups to work together. The work will gain broad exposure in premier materials, chemistry, and physics journals, and through presentations at major scientific conferences. Interdisciplinary research. This project combines cutting edge colloidal chemistry - including the synthesis,fabrication,functionalization and catalysis - with cutting edge colloidal physics - including auto-electrokinetic phenomena and simulations. This research also impacts both graduate and undergraduate students by requiring highly multidisciplinary work. Students will learn cutting-edge techniques employed in chemistry, chemical engineering, and nanofabrication, as well as modeling strategies for dynamic systems. Velegol and Sen propose a project which exemplifies the interdisciplinary nature of modern advanced fundamental science programs.