Structure and Chemical Interactions at Model Polymer Interfaces

9801739阿拉拉这个项目的目标是增加对有机材料界面基本行为的基本理解。虽然人们普遍认识到，底物结构和化学的细节在决定界面性质方面起着关键作用，但目前对聚合物界面的主流研究只在总的努力中投入了一小部分。这项拟议的工作旨在通过研究以受控方式限制在定义明确的表面上的链来填补这一重要空白。根据主要调查者过去工作结果的新发展，提出了三个平行的分推力：1)聚亚甲基(PM)纳米团簇对过渡金属表面约束的形态效应；表面接枝链组件润湿过程中的界面重构效应；被吸附的柔性链的结构和动力学受受控制的建筑表面位置和/或次级吸附物种的限制。在第一区中，我们将深入探讨各种金属晶面上的限制效应对PM的结构和相变的影响。此外，聚合物将随着侧链的夹杂而发生变化，并将进行有限的延伸以制备新型的聚合物纳米复合材料。在区域2中，将进行相关的实验和理论研究，以便更广泛地理解表面约束链系统中的润湿诱导重建。在区域3中，吸附聚合物的链结构密度分布将与主要通过分子自组装形成的“调谐”衬底钉扎位模式和地形相关联。此外，还将通过化学诱导的界面扰动和化学吸附分子陷阱(“钉书钉”)对脱附动力学的影响来研究链重组和脱附动力学。总体而言，这些研究跨越了柔性链结构S，从固体纳米晶到无序的链组装，限制在化学和地形控制的表面。%拟议工作的结果预计将在从聚合物粘合到微电子到生物相容性的各个领域产生影响。它们可以提高对复杂有机界面的性质建立定量模型的能力，从而增强设计材料结构的能力，这些材料结构的性能关键取决于这些类型的界面的性质。***

9801739 Allara The goal of this project is to provide an increased fundamental understanding of the underlying behavior of the interfaces of organic materials. While it is generally well appreciated that the details of substrate structure and chemistry play a critical role in determining the interface properties, the current mainstream research in polymer interfaces has placed only a small fraction of total effort here. The proposed work is intended to fill this important gap through studies of chains confined at well-defined surfaces in controlled ways. Based on new developments in the past results from the principal investigator's work, three parallel sub-thrusts are proposed: 1.) morphological effects of surface confinement of polymethylene (PM) nano-clusters on transition metal surfaces; 2.) interface reconstruction effects in wetting of surface-grafted chain assemblies; and 3.) structure and dynamics of adsorbed flexible chains constrained at controlled architecture surface sites and/or by secondary adsorbate species. In area 1 the work will probe deeply into confinement effects on structure and phase transitions of PM on varied metal crystal faces. Further, the polymer will be varied by inclusions of side chains and limited extensions will be made to prepare novel types of polymer nano- composites. In area 2 connected experimental and theoretical studies will be made to develop a broader understanding of wetting-induced reconstruction in surface-constrained chain systems. In area 3 the chain structure density distribution for adsorbed polymers will be correlated with "tuned" substrate pinning site patterns and topography, primarily made via molecular self-assembly. In addition, chain reorganization and desorption dynamics will be studied via chemically-induced interface perturbations and effects of chain confinement imposed by chemisorbed molecular traps ("staples") on desorption kinetics studied. Overall these studies span flexible chain structure s, ranging from solid nanocrystallites to disordered chain assemblies, confined at chemically and topographically controlled surfaces. %%% The results of the proposed work are expected to have impact in areas ranging from polymer adhesion to microelectronics to biocompatability. They may provide an increased ability to make quantitative models of the properties of complex organic interfaces and thereby to enhance the ability to engineer materials structures whose performance depends critically upon the nature of these types of interfaces. ***