TOWARDS SELF-ASSEMBLYING ACTIVE MICRO-STRUCTURES

非技术总结材料研究部和化学部为该奖项提供资金。它支持专注于将活性纳米颗粒自组装成功能结构的理论研究和教育。活性物质是软凝聚态物质和材料科学中一个令人兴奋的领域，在过去的十年里已经崭露头角。能够以每秒几十微米的速度在溶液中自推进的胶体粒子的合成在这一领域的出现中发挥了重要作用。推进机制是通过将化学能量或更广泛地说是环境能量转化为粒子的定向运动而获得的。在这些系统中，主动和热力之间的相互作用导致了一种非凡的集体行为，这让人想起在生命系统中观察到的现象，如鱼群成群、鸟类成群或细菌成群。这些纳米粒子最吸引人的特点之一是，与生物实体不同，它们可以被合成成任意复杂的形状，并具有广泛的颗粒间相互作用。此外，它们的主动行为可以通过外部光源来触发和调节。该项目的目标是使用理论和计算机模拟相结合的方法来理解如何利用这些推进力来增强粒子自发形成有组织结构的过程，这一过程被称为自组装。PI的目标是找到方法来极大地加快这一原本漫长的过程，并发现新的策略来设计不仅具有目标静态性能，而且可以在微观尺度上执行工作的材料。该项目旨在通过提出新的结构形成途径，显著推动纳米粒子自组装和材料工程领域的发展，并将其应用于刺激响应材料的制造和纳米药物的制造。该项目还有一个强大的教育部分，包括对研究生和本科生的培训，与致力于提高妇女和科学界代表性不足的少数群体的校园组织合作，以及为移动平台开发教育软件。技术总结材料研究司和化学司为该奖项提供资金。它支持理论研究和教育，目的是了解和控制活性纳米颗粒的自组装。使活性系统非常令人兴奋的是，它们在单个粒子水平上本质上是不平衡的，因此产生了比平衡系统中可能的更复杂的集体行为。研究小组计划使用理论和数值模拟来开发合理的设计策略，以设计活性粒子的功能聚集体。这将通过研究颗粒各向异性、流体动力相互作用和波动激活场在活性纳米颗粒自组装动力学中所起的关键作用来实现。了解粒子的几何形状、相互作用的方向性以及如何利用作用力的强度来优化自组装结构并赋予其功能是该领域最重要的挑战之一。该团队还将分析活性纳米颗粒及其形成的材料如何对随时间和空间波动的推动力做出反应。活性物质的这一领域具有潜在的应用前景，范围从可切换材料到微型致动器的开发。这项研究的最终目的是了解如何操纵所有这些参数来直接干预和动态影响结构形成的路径。这项研究可能会对材料科学和工程产生重要影响，因为它可能导致开发出更好的策略，以自下而上的方法进行主动结构设计。该项目涉及的基本问题也将对依赖类似物理机制的生物系统以及纳米医学产生重要影响。该奖项有助于本科生和研究生的教育。研究小组将参加由致力于提高妇女和科学界代表性不足的少数群体的校园组织赞助的外联活动，并将为手持设备开发教育软件，以突出研究成果。

NONTECHNICAL SUMMARYThe Division of Materials Research and the Division of Chemistry contribute funds to this award. It supports theoretical research and education focused on self-assembly of active nanoparticles into functional structures. Active matter is an exciting field in soft condensed matter and materials science that has come into prominence over the last decade. The synthesis of colloidal particles that can self-propel in solution at speeds of tens of microns per second played an important role in the emergence of this field. The propulsion mechanism is obtained by conversion of chemical or, more generally, environmental energy, into directed motion of the particles. The interplay between active and thermal forces in these systems gives rise to a remarkable collective behavior that is reminiscent of phenomena observed in living systems such as in schooling of fish, flocking of birds, or swarming of bacteria. One of the most appealing features of these nanoparticles is that, unlike biological entities, they can be synthesized into arbitrarily complex shapes and with a wide range of inter-particle interactions. Furthermore, their active behavior can be triggered and tuned with an external light source. The goal of this project is to use a combination of theory and computer simulations to understand how these propelling forces can be used to enhance the spontaneous formation of particles into organized structures, a process known as self-assembly. The PI aims to find ways to greatly speed up this otherwise lengthy process, and to uncover new strategies to design materials that not only have targeted static properties, but that can also perform work at the micro-scale. This project is aimed to significantly advance the field of nanoparticle self-assembly and materials engineering by suggesting new pathways of structure formation, with applications in manufacturing of stimuli-responsive materials and nano-medicine. The project has also a strong educational component, which includes training of graduate and undergraduate students, collaboration with on-campus organizations dedicated to the advancement of women and underrepresented minorities in science, and development of educational software for mobile platforms.TECHNICAL SUMMARYThe Division of Materials Research and the Division of Chemistry contribute funds to this award. It supports theoretical research and education with the aim of understanding and controlling self-assembly of active nanoparticles. What makes active systems very exciting is that they are intrinsically out of equilibrium at the single particle level, thus generating a much more complex collective behavior than is possible in equilibrium systems. The research team plans to use theory and numerical simulations to develop rational design strategies to engineer functional aggregates of active particles. This will be achieved by studying the key role played by particle anisotropy, hydrodynamic interactions, and fluctuating activating fields in the self-assembly dynamics of active nanoparticles. Understanding how the geometry of the particles, the directionality of their interactions, and how the strength of the active forces can be exploited to optimize and impart functionality to self-assembled structures is one of the most important challenges in the field. The team will also analyze how active nanoparticles and the materials they form respond to propelling forces that can fluctuate over space and time. This field in active matter holds promise for potential applications that range from switchable materials to the development of microscopic actuators. The ultimate goal of this research is to be able to understand how to manipulate all these parameters to directly intervene in and dynamically affect the pathway of structure formation.This research may have an important impact in materials science and engineering as it could lead to the development of better strategies for a bottom-up approach to active structure design. The fundamental questions addressed in this project will also have important implications for biological systems that rely on similar physical mechanisms, and in nano-medicine. This award contributes to the education of undergraduate and graduate students. The research group will participate in outreach activities sponsored by on-campus organizations dedicated to the advancement of women and underrepresented minorities in science, and will develop educational software for hand-held devices to highlight the results of the research.