Investigation of In Situ Interfacial Polymer Structure by Surface Sum-Frequency Generation

这项研究计划补助金是由分析和表面化学计划支持的。梅斯默教授和她在利哈伊大学的学生将研究聚合物界面的结构，目的是了解聚合物链的结构如何影响这些表面的摩擦学性能。这项工作将把表面化学键的取向及其构象与相变和摩擦特性等性质联系起来。原位和频产生光谱将被用来确定这些聚合物表面的键级和结构的程度，因为这种二阶光学方法只对界面区域敏感，而对通常在表面光谱中主导信号的本体性质不敏感。这项工作将从聚烯烃和聚氧化乙烯薄膜在熔融二氧化硅表面组成的模型二嵌段聚合物开始，以便C-H拉伸、C-C弯曲和摇摆模式可以作为组成和环境变量的函数来量化。这项工作的结果将确定强烈影响这些界面摩擦特性的表面属性。这项工作旨在为利用一种表面敏感的光谱方法--原位和频谱来预测聚合物材料的表面摩擦性能奠定基础。将对模型二嵌段聚合物进行初步研究。通过对这些聚合物表面的组成和结构的灵敏测量，将建立起极大地控制表面摩擦的小特征。本工作在润滑、抗絮凝剂、防护涂料等重要技术领域有着广泛的应用。

This Research Planning Grant is supported by the Analytical and Surface Chemistry Program. Professor Messmer and her students at Lehigh University will study the structure of polymeric interfaces with the aim to understand how the structure of polymeric chains affects the tribological properties of these surfaces. This work will correlate the orientation of surface chemical bonds and their conformation with properties such as phase transitions and frictional characteristics. In situ sum-frequency generation spectrometry will be used to determine the degree of bond order and structure for these polymeric surfaces because this second order optical method is sensitive only to interfacial regions and not to bulk properties that often dominate signals in surface spectroscopy. The work will begin with model diblock polymers composed of polyolefins and polyethylene oxide films on fused silica surfaces so that C-H stretching, and C-C bending and rocking modes can be quantified as a function of compositional and environmental variables. Results from this work will identify surface properties that strongly influence the frictional character of these interfaces. This work aims to develop a foundation for predicting the surface frictional properties of polymeric materials through the use of a surface sensitive spectroscopic method, in situ sum-frequency spectrometry. Model diblock polymers will be studied initially. Through sensitive measurements of the composition and structure of these polymeric surfaces, small features that greatly control surface friction will be established. This work has broad application in many important technological areas such as lubrication, anti-flocculating agents, and protective coatings.