The Dynamics of Organic Films on Different Time Scales

非技术摘要本项目的重点是烷烃[化学式CnH 2n +2]薄膜，柔性链状分子，在材料科学中作为用于涂料，粘合剂和电子设备的更复杂聚合物的原型受到普遍关注。 烷烃也是商业润滑剂的主要成分。 对烷烃膜的结构和动力学性质的微观理解可能会导致技术进步，从更耐用的聚合物涂层到减少汽车发动机和计算机硬盘等纳米级设备磨损的润滑剂。 该项目将利用高分辨率中子散射和计算机模拟作为主要技术，以确定柔性烷烃分子改变其形状的速率以及这些构象变化如何影响分子粘附在固体表面的能力。 实验将在国家标准和技术研究所中子研究中心和橡树岭国家实验室新建的Spiritual中子源的最先进的中子谱仪上进行。 该项目包括利用原子力显微镜、阿贡国家实验室的同步加速器X射线散射和密苏里州大学研究反应堆的中子衍射进行结构研究。 这项研究将为本科生和研究生提供聚合物科学基础方面的培训，为他们在工业界和学术界以及在我们不断扩大的国家中子和X射线散射设施中的职业生涯做好准备。DMR-0705974提案标题：有机薄膜在不同时间尺度上的动力学PI/PD：Haskell Taub该项目侧重于烷烃[CnH 2n +2]薄膜，柔性链状分子，在材料科学中作为用于涂料，粘合剂和电子设备的更复杂聚合物的原型。 烷烃也是商业润滑剂的主要成分。 一个基本的问题与膜的中间长度的烷烃分子（15 n 50）的影响，在分子的形状（构象）的变化引起的加热可能有结合的分子到一个固体表面，并在宏观水平上，润湿的流体膜的表面。 这些构象的变化是重要的，了解这样的技术上的重要现象，如薄的润滑膜从磁存储磁盘的表面上的蒸发，烷烃从催化表面的解吸，和烷烃膜的润滑特性。 该项目将利用准弹性中子散射和分子动力学模拟作为主要技术，研究吸附在固体表面上的烷烃膜在一系列时间尺度（皮秒至纳秒）内发生的分子构象变化。 实验将在国家标准和技术研究所中子研究中心和橡树岭国家实验室新建的Spectron中子源的最先进的中子谱仪上进行。 由于动态实验的解释需要薄膜结构的知识，该项目包括利用原子力显微镜，同步加速器X射线散射在阿贡国家实验室，和中子衍射在密苏里州大学研究反应堆的结构研究。 这项研究将为本科生和研究生提供聚合物科学基础方面的培训，为他们在工业和学术界以及我们不断扩大的中子和X射线散射国家设施中的职业生涯做好准备。

Non-technical AbstractThis project focuses on films of alkanes [chemical formula CnH2n+2], flexible chain-like molecules that are of general interest in materials science as prototypes of more complex polymers used in coatings, adhesives, and electronic devices. Alkanes are also the principal constituents of commercial lubricants. A microscopic understanding of the structural and dynamical properties of alkane films could potentially lead to technological advances ranging from more durable polymer coatings to lubricants that reduce wear in automobile engines and in nanoscale devices such as computer hard drives. This project will utilize high-resolution scattering of neutrons and computer simulations as the principal techniques to determine the rates at which flexible alkane molecules change their shape and how these conformational changes affect the molecules' ability to stick to a solid surface. Experiments will be conducted on state-of-the-art neutron spectrometers at the Center for Neutron Research at the National Institute of Standards and Technology and at the newly constructed Spallation Neutron Source at Oak Ridge National Laboratory. The project includes structural studies utilizing Atomic Force Microscopy, synchrotron x-ray scattering at Argonne National Laboratory, and neutron diffraction at the University of Missouri Research Reactor. This research will provide training of undergraduate and graduate students in fundamental aspects of polymer science, preparing them for careers in industry and academia as well as at our expanding national facilities for neutron and x-ray scattering.Technical AbstractProposal No.: DMR- 0705974Proposal Title: The Dynamics of Organic Films on Different Time ScalesPI/PD: Haskell TaubThis project focuses on films of alkanes [CnH2n+2], flexible chain-like molecules that are of general interest in materials science as prototypes of more complex polymers used in coatings, adhesives, and electronic devices. Alkanes are also the principal constituents of commercial lubricants. A fundamental issue concerned with films of intermediate-length alkane molecules (15 n 50) is the effect that changes in molecular shape (conformation) induced by heating may have on binding of molecules to a solid surface and, at a macroscopic level, the wetting of the fluid film to a surface. These conformational changes are important for understanding such technologically important phenomena as the evaporation of thin lubricant films from the surfaces of magnetic storage disks, the desorption of alkanes from catalytic surfaces, and the lubricating characteristics of alkane films. This project will utilize quasielastic neutron scattering and molecular dynamics simulations as the principal techniques to investigate the molecular conformational changes that occur over a range of time scales (picoseconds to nanoseconds) in alkane films adsorbed on solid surfaces. Experiments will be conducted on state-of-the-art neutron spectrometers at the Center for Neutron Research at the National Institute of Standards and Technology and at the newly constructed Spallation Neutron Source at Oak Ridge National Laboratory. Since interpretation of the dynamical experiments requires knowledge of the film structure, the project includes structural studies utilizing Atomic Force Microscopy, synchrotron x-ray scattering at Argonne National Laboratory, and neutron diffraction at the University of Missouri Research Reactor. This research will provide training of undergraduate and graduate students in fundamental aspects of polymer science, preparing them for careers in industry and academia as well as at our expanding national facilities for neutron and x-ray scattering.