Quantitative Imaging & Microanalysis of Nano-Aggregates in Styrenic Ionomers

9906829 Winey本研究项目的总体目标是解决离聚物形态学中突出和有争议的问题，特别是关于离子聚集体。 在前三年，这项工作将集中在模型随机离聚物的散装，特别是基于聚苯乙烯的离聚物，并完成四个主要的科学目标。 (1)使用亮场和/或环形暗场扫描透射电子显微镜，PI将从尺寸、形状和尺寸分布开始定量和完整地表征离子聚集体。 她将使用STEM中倾斜序列的三维重建来确定聚集体的空间分布，包括最近接近的距离。 此外，在电子显微镜（空间分辨EELS，EDS和定量ADF STEM）内的微量分析方法的集合将定量确定离子聚集体和基质的组成。 (2)再次使用电子显微镜，PI将测量10 - 1000 nm长度尺度上阳离子的空间分布，以评估低角度散射强度上升的起源。 (3)利用从定量成像和微观分析中获得的形态信息，她将开发一个小角度X射线散射模型。 (4)纳米聚集体的动力学将使用电子显微镜中的加热/冷却阶段和变形阶段进行研究。 在整个项目中，PI将评估具有各种材料特性（%酸、%中和、反离子类型、酸类型等）的苯乙烯离聚物，以确定它们对纳米级形态的影响。 集成和独特的一套工具，可以使用比以前尝试的分子参数和形态之间的关系更严格。这项工作是在纳米科学和纳米材料的技术重要领域。 PI将培养一名聚合物科学和高分辨率、化学特异性成像的研究生，这是一种目前聚合物科学家和工业家未充分利用的技术。 此外，她还将培训这些先进技术的工业和学术科学家。

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.