Quantitative Imaging & Microanalysis of Nano-Aggregates in Styrenic Ionomers

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9906829WineyThe overall objective of this research project is to resolve outstanding and disputed questions in ionomer morphology, particularly in regard to the ionic aggregates. During the first three years, the work will focus on model random ionomers in the bulk, specifically ionomers based on polystyrene, and accomplish four major scientific goals. (1) Using bright and/or annular dark field scanning transmission electron microscopy, the PI will quantitatively and completely characterized the ionic aggregates starting with size, shape and size distribution. She will use three-dimensional reconstruction from tilt series in STEM to determine the spatial distribution of the aggregates, including the distance of closest approach. In addition, an ensemble of microanalysis methods within the electron microscope (spatially resolved EELS, EDS, and quantitative ADF STEM) will quantitatively determine the compositions of the ionic aggregates and the matrix. (2) Again using electron microscopy, the PI will measure the spatial distribution of cation over a 10 - 1000 nm length scale to assess the origin of the upturn in scattering intensity at low angles. (3) Using the morphological information obtained from quantitative imaging and microanalysis, she will develop a small angle x-ray scattering model. (4) The dynamics of nano-aggregates will be studied using a heating/cooling stage and a deformation stage in the electron microscope. Throughout this project the PI will evaluate sytrenic ionomers with various materials characteristics (%acid, %neutralization, counterion type, acid type, etc.), to establish their influence on the nano-scale morphology. The integrated and unique set of tools to be used permits a more rigorous correlation between molecular parameters and morphology than previously attempted.This work is in the technologically important area of nanoscience and nanomaterials. The PI will train one graduate student in polymer science and high resolution, chemically specific imaging, a technique, which is currently underutilized by polymer scientists and industrialists. In addition, she will also train industrial and academic scientists in these advanced techniques.