Quantitative Imaging & Microanalysis of Nano-Aggregates in Styrenic Ionomers

[906829]本研究项目的总体目标是解决离子聚体形态学方面的突出和有争议的问题，特别是关于离子聚集体的问题。在前三年，工作将集中在大量的模型随机离聚体，特别是基于聚苯乙烯的离聚体，并完成四个主要的科学目标。(1)利用明暗场扫描电镜和环形暗场扫描电镜，PI将从大小、形状和大小分布等方面对离子聚集体进行定量和完整的表征。她将在STEM中使用倾斜序列的三维重建来确定聚集体的空间分布，包括最接近的距离。此外，电子显微镜内的微分析方法（空间分辨EELS， EDS和定量ADF STEM）将定量确定离子聚集体和基质的组成。(2)同样使用电子显微镜，PI将测量10 - 1000 nm长度范围内阳离子的空间分布，以评估低角度散射强度上升的来源。(3)利用定量成像和显微分析获得的形态学信息，建立小角度x射线散射模型。(4)采用电子显微镜下的加热/冷却阶段和变形阶段对纳米聚集体的动力学进行研究。在整个项目中，PI将评估具有不同材料特性（%酸、%中和、反离子类型、酸类型等）的共离聚体，以确定它们对纳米级形貌的影响。所使用的综合和独特的一套工具允许分子参数和形态之间比以前尝试的更严格的相关性。这项工作是纳米科学和纳米材料技术的重要领域。该项目将培养一名高分子科学和高分辨率化学特异性成像方面的研究生，这是目前高分子科学家和实业家未充分利用的一项技术。此外，她还将为工业界和学术界的科学家提供这些先进技术的培训。

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.