Novel Photoreactive Amphiphilic Polymers: Synthesis, Photophysics, and Theory

拟议的研究项目涉及合成含有共价结合发色团的线形和树枝状聚合物，这些聚合物将用作荧光探针来表征聚合物体系本身或阐明聚合物环境对光化学过程的影响。要研究的聚合物是两亲性的，具有疏水的嵌段或末端和亲水的嵌段或表面。由于这些块的溶解度有很大的差异，这些材料可以自组装成胶束结构或吸附到疏水表面，包括液-液界面。自组装的性质取决于分子结构和溶剂/温度条件。能量转移、随时间变化的荧光去偏振和荧光猝灭等荧光方法的组合将被用来表征下列体系中聚合物链段的环境和空间排列：1)来自双嵌段聚合物的聚合物胶束；2)表面吸附的双嵌段或疏水末端标记的聚合物；3)共价末端接枝到表面的聚合物；4)树枝状聚合物在均相溶液中或共价键合在表面。除了这些合成和光物理实验外，我们还应用计算方法来模拟界面上的聚合物。这些将有助于我们实验的设计和解释，并为可用于测试聚合物在界面上的预测或分析理论的数值方法提供有用的补充。这项光物理研究旨在阐明聚合物如何修饰或影响界面上的反应。潜在的应用包括光反应膜、凝胶、胶束和表面活性剂。

The proposed research project involves the synthesis of linear and dendrimeric polymers that contain covalently-bound chromophores will serve a dual purpose as fluorescent probes to characterize the polymer system itself or to elucidate the effect of the polymer environment on photochemical processes. The polymers to be studied are amphiphilic, with a hydrophobic block or end and a hydrophilic block or surface. Because of the strong differences in the solubility of these blocks the materials can self-assemble into micelle structures or adsorb onto hydrophobic surfaces, including liquid-liquid interfaces. The nature of the self-assembly depends on the molecular architecture and solvent/temperature conditions. A combination of fluorescence methods such as energy transfer, time-dependent fluorescence depolarization, and fluorescence quenching will be used to characterize the environment and spatial arrangement of polymer segments in the following systems: 1) polymer micelles from diblock polymers; 2) surface adsorbed diblock or hydrophobically end-tagged polymers; 3) polymers covalently end- grafted to surfaces; 4) dendrimeric polymers either in homogeneous solution or covalently bonded to a surface. In addition to these synthetic and photophysical experiments, we have undertaken the application of computational methods to simulate polymers at interfaces. These are expected to help in the design and interpretation of our experiments and provide a useful additions to the numerical methods available to test predictions or analytical theory of polymers at interfaces. This photophysical research aims to clarify how polymers can modify or effect reactions at interfaces. Potential applications include photoreactive films, gels, micelles, and surfactants.