Adhesive and Mechanical Behavior of Short Molecules

分子自组装单层（SAMs）是一种高度组织化的表面薄膜，厚度为1分子（2-3纳米），由短有机分子组成，像麦田里的麦秆一样组装在一起。它们支配着薄膜的结构、机械和粘合行为。从粘合剂到微机械润滑剂，再到纳米光刻和纳米结构器件和材料，sam对各种工程系统都很重要。在所有情况下，为了设计使用地对空导弹的系统，必须了解其粘接、摩擦和机械行为。然而，人们对这些行为知之甚少，特别是在组合载荷下。本研究的假设是，sam的力学行为可以从相对简单的应力状态的分子分析中获得，并用于纳米压痕实验和越来越多的sam基材料系统和结构中出现的更复杂的应力状态的连续分析。这一假设将在几种不同的SAMs和表面上进行检验，使用更广泛的简单表征应力状态和时间尺度的分子分析，以及使用界面力显微镜探针进行切向加载的正常压痕实验。该项目将提供受过广泛训练的学生，他们将在大学或工业的跨学科环境中富有成效地工作。一名本科生也将参与该项目。德克萨斯州的人口统计数据表明，德州大学奥斯汀分校的本科生中有相当多的西班牙裔代表（约占ASE系的20%），我们成功地鼓励他们参加我们的本科生拓展计划。

Molecular self-assembled monolayers (SAMs) are highly organized surface films, one molecule (2-3 nm) thick, composed of short organic molecules which assemble like stalks of wheat on a wheat field. They govern the structure and mechanical and adhesive behavior of the films. SAMs are important for a wide range of engineered systems, from adhesives to micromachine lubricants to nanolithography and nanostructured devices and materials. In all cases, the adhesive, frictional and mechanical behavior must be understood for the design of systems that make use of SAMs However, very little is known about this behavior, particularly under combined loadings.The hypothesis for this study is that the mechanical behavior of SAMs may be obtained from molecular analyses of relatively simple stress states and used in continuum analyses of more complex stress states that arise in nanoindentation experiments and in the growing array of SAM-based materials systems and structures. This hypothesis will be examined for several different SAMs and surfaces using molecular analyses of a broader range of simple characterizing stress states and time scales, and normal indentation experiments coupled with tangential loading using interfacial force microscope probes.The project will provide broadly trained students who will be productive working in interdisciplinary environments at universities or in industry. One undergraduate student will also be incorporated in the project. Texas demographics are such that the undergraduate body at UT-Austin has a significant Hispanic representation (~20% in the ASE Department), who we successfully encourage to participate in our undergraduate outreach programs.