Nanostructured Material Synthesis in a Self-Assembled Surfactant Mesophase

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ABSTRACTCTS-9909912John, Vijay/Tulane U.We propose a collaborative project to develop new nanostructured materials by exploiting the potentially templating environment of a self-assembled surfactant gel phase. The novelty of the gel is the fact that it contains equal volumes of water and an oil phase, thus opening up several possibilities of synthesis in dual hydrophobic and hydropbilic microenvironments. Our hypothesis is that the spatial immobilization of the hydrophobic and the hydrophilic regions will allow the formation of extended structures that are organized over multiple length scales. Our research thus seeks to systematically understand the gel phase and to exploit its features for materials synthesis.The gel mesophase is formed by adding lecithin (phosphatidylcholine) to AOT-in-isooctane reverse micelles and increasing the water content of the system. The gel is formed when the volume fractions of water and isooctane become approximately equal, and continues to be stable upon further increase of the water content. The gel is optically clear and rigid. Our objective therefore is to synthesize materials in the hydrocarbon and aqueous microphases, or to exploit the properties of an oil-water interface that is immobilized over large length scales, for interfacial synthesis, We propose the synthesis of (a) polymer and inorganic materials with extended nanostructures, (b) polymer-inorganic nanocomposites where the polymer is synthesized in the oil phase or at the oil-water interface, and the inorganic component is synthesized in the aqueous phase, and (c) polymer-polymer structured nanocomposites using hydrophobic and hydrophilic monomers. Four different examples of materials synthesis are chosen. If these can be successfully demonstrated, the conceptual framework for generating an array of other important materials will have been developed.Together with materials synthesis, we will concurrently carry out extensive studies to understand the microstructure of the gel phase and to correlate the gel microstructure with the morphology of the materials synthesized in the gel. The proposed work will use the AOT reverse micellar system as a reference point and seek to understand the transition to the gel phase. The synthesis of nanoparticles in AOT reverse micelles has been well-studied and it will be of interest to follow morphology evolution as the system follows the composition trajectory to the gel phase. Thus the research will seek to provide an understanding of how materials morphology can be systematically changed by the microstructure evolution of the templating medium.The research is a collaboration between researchers at Tulane University and the University of Rhode Island. It is anticipated that such collaboration will expose the students involved, to a broad range of scientific experimental techniques and expertise. The PIs will seek to integrate their research with education both at the graduate and at the undergraduate level.