Chemical simulations of stress-activated functional molecules and materials

近年来，人们在开发功能分子和材料系统方面做出了巨大的努力。在许多情况下，这些系统被设计成经历化学反应，该化学反应响应于诸如光、热或电流的外部刺激而执行机械功。例子包括分子梭和马达、行走塑料和微观致动器。另一种较少探索的途径涉及相反的过程，即通过使系统受到外部应力而对系统进行机械功来诱导化学反应。考虑到许多现实世界系统中存在的固有的大应力，应力激活系统的开发可能具有显著的益处。例如，可以开发响应和适应滑动接触中变化的应力以最佳地控制摩擦和磨损的功能性润滑剂、检测基础结构中的损坏的分子应力传感器，以及甚至响应于在特定细胞位点吸附时所经历的应力而被激活的药物递送系统。为了开发应激激活的功能系统，有必要了解施加的应激和化学反应之间的关系。拟议的研究将使用量子化学模拟来实现这一目的，并遵循三个综合途径。首先，将开发新的方法，以允许模拟受到应力和应变的现实模型系统。第二，这些技术将与传统的模拟方法一起沿着用于研究分子系统如何对外部应力作出反应。模拟将侧重于摩擦化学，其中涉及润滑接触中发生的反应，以及机械化学，其中涉及通过拉伸分子系统激活反应。第三，研究结果将用于制定预测模型，将分子水平的行为与宏观性质联系起来，以指导应力激活功能系统的合理开发。这项工作本身借鉴了化学，物理，材料科学，应用数学，计算机科学和工程，这将提供五个研究生和两个博士后研究员宝贵的跨学科经验。

Recent years have witnessed tremendous efforts aimed at developing functional molecular and materials systems. In many cases, these systems are designed to undergo chemical reactions that perform mechanical work in response to external stimuli such as light, heat, or an electrical current. Examples include molecular shuttles and motors, walking plastics, and microscopic actuators. An alternative, less-explored avenue involves the opposite process in which chemical reactions are induced by performing mechanical work on the system by subjecting it to external stresses. The development of stress-activated systems may have significant benefits given the inherently large stresses present in many real-world systems. For example, it may be possible to develop functional lubricants that respond and adapt to the changing stresses in sliding contacts to optimally control friction and wear, molecular stress sensors that detect damage in infrastructure, and even drug delivery systems that are activated in response to the stresses experienced upon adsorption at specific cellular sites. To develop stress-activated functional systems, it is necessary to understand the relationship between applied stress and chemical reactions. The proposed research will use quantum chemical simulations for this purpose and follow three integrated avenues. First, new methods will be developed to permit simulations of realistic model systems subjected to stresses and strains. Second, these techniques will be used along with conventional simulation methods to study how molecular systems respond to external stresses. The simulations will focus on tribochemistry, which involves reactions occurring in lubricating contacts, and mechanochemistry, which involves the activation of reactions by stretching molecular systems. Third, the results will be used to formulate predictive models relating molecular-level behaviour to macroscopic properties to guide the rational development of stress-activated functional systems. The work itself draws on chemistry, physics, materials science, applied mathematics, computer science, and engineering, which will provide five graduate students and two postdoctoral fellows with valuable interdisciplinary experience.