Novel Photoreactive Amphiphilic Polymers: Synthesis, Photophysics, and Theory

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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.