FRG: X-Ray Scattering Studies of Structure and Dynamics of Polymer Interfaces

这是加州大学圣地亚哥分校、北伊利诺伊大学和耶鲁大学之间的焦点研究小组奖。其目的是利用国家同步辐射和中子散射设施的X射线和中子散射的非侵入性证据，对聚合物薄膜进行详细的结构和动力学研究，以便在微观水平上更好地科学地了解大分子在固/液界面以及在液体状态和玻璃化转变周围的自由(液体/蒸汽)表面的静态和动态行为。这种科学的理解是必要的，因为目前关于聚合物表面起伏和聚合物薄膜中玻璃化转变的性质的实验结果和理论观点有相当大的分歧。需要更详细地阐明限制的作用(例如，当薄膜厚度与聚合物链的回转半径相当时)和聚合物-基质相互作用的作用，以实现这样的理解。解决这些问题的技术包括X射线和中子反射率、漫反射X射线散射、小角中子散射和X射线光子相关光谱。推动这一项目的科学兴趣源于我们目前对聚合物分子的构象和迁移率如何受到薄膜限制和与衬底相互作用的影响以及这些材料如何转变为玻璃态的有限知识。它的技术重要性与聚合物薄膜在工业和技术中所发挥的重要作用有关，这些薄膜形式包括涂料、粘合剂、用于化学分离的过滤器、包装材料、用于微电子设备的光刻掩模等。此外，它将为三个不同教育机构的学生和博士后研究人员提供机会，使他们有机会接受这一重要材料科学领域的培训，并利用国家一流的使用同步加速器X射线和中子束的研究设施来使用先进的研究方法。

This is a Focused Research Group award between the University of California in San Diego, Northern Illinois University, and Yale University. Its aim is to carry out detailed structural and dynamical studies of polymer films, using the non-invasive proves of x-ray and neutron scattering at national synchrotron radiation and neutron scattering facilities, in order to achieve a better scientific understanding at the microscopic level of the static and dynamic behavior of macromolecules at solid/liquid interfaces and at free (liquid/vapor) surfaces in the fluid state and around the glass transition. This scientific understanding is needed because at present there is a considerable divergence of results from experiments and also of theoretical views regarding the nature of the fluctuations at polymeric surfaces and of the glass transition in thin polymer films. The roles of confinement (e.g. when the film thickness is comparable to the radius of gyration of the polymer chains) and of the polymer-substrate interactions need to be elucidated in more detail to achieve such an understanding. The techniques to be brought to bear on these problems include x-ray and neutron reflectivity, diffuse x-ray scattering, small-angle neutron scattering and x-ray photon correlation spectroscopy.The scientific interest driving this project stems from our present limited knowledge of how the conformation and mobility of polymer molecules are affected by confinement to a thin film and by interactions with the substrate and how these materials transform into the glassy state. It's technological importance is related to the important role played by polymer films in industry and technology in the form of coatings, adhesives, filters for chemical separations, packaging materials, lithographic masks for microelectronic devices, etc. Further, it will provide an opportunity for students and postdoctoral researchers at three different educational institutions to be trained in this important area of materials science and in the use of advanced research methods utilizing the nation's premier national facilities for research using synchrotron x-ray and neutron beams.