Controlling Ionomer Morphologies

这项拟议的研究将使用模型材料和各种分析电子显微镜(AEM)方法来研究含离子聚合物，特别是离聚体的形态。离聚体是含有大部分非极性单体单元和少量(~5-10摩尔%)极性单体单元的无规共聚物，通常是酸，如-COOH。酸性基团可以与阳离子中和，以生成离子物种，如-COO-Na+，在Na中和的羧酸的情况下。由于这些离子物种比周围的基质具有更强的极性，因此有驱动力使这些离子物种微相分离并形成离子聚集体，尽管由此产生的离子聚集体的形态还不是很清楚。控制离聚体的形态是拟议研究的主要目标，也是开发这些材料的预测性理论模型和对其结构-性能关系的可靠理解的第一步。这些离子聚集体充当物理交联剂，以增韧聚合物，并导致当前的工业应用(耐化学腐蚀的热塑性塑料、坚韧的涂料、燃料电池的渗透选择膜和食品包装材料)和各种潜在的技术应用(例如，防止化学战)。这些复杂的聚合物材料激发了科学兴趣，因为(1)这些两亲性材料具有模拟生物大分子的离子相互作用，(2)离聚体容易获得，包括非晶态和半结晶聚合物以及一系列阳离子，以及(3)现在可以使用高分辨率分析工具来研究化学、加工、形态和性能的相互依赖关系。WINEY自1998年以来对离聚体的扫描透射电子显微镜(STEM)研究为拟议的研究提供了有价值的基础，在该研究中，WINEY努力确定对离聚体形态有最重大影响的材料参数和工艺条件。这项拟议的工作旨在揭示离聚体形态的可靠趋势，以便提供对这些复杂材料的基本理解。当Winey确定各种材料和工艺参数如何影响离聚体形态时，他们将能够控制离聚体形态。拟议实验计划的两个特点是(1)使用模型材料，即为解决特定科学问题而设计的材料，(2)使用多种表征工具，包括SAXS、FT-IR，特别是一系列分析电子显微镜(AEM)方法。工业、学术和军事科学家对拟议的含离子聚合物的研究和聚合物的AEM表征工具的开发都有科学兴趣。WINEY将与利哈伊显微镜学院合作，确保电子显微镜工作者充分利用拟议工作中使用的AEM方法来研究复杂的、化学上不均匀的聚合物材料。此外，维尼将继续担任宾夕法尼亚大学校园女性工程师协会的教职联合顾问，并每年举行一次关于工程学研究生学习和学术生涯机会的小组讨论。

The proposed research will investigate the morphology of ion-containing polymers, in particular ionomers, using model materials and a variety of analytical electron microscopy (AEM) methods. Ionomers are random copolymers with a majority of non-polar monomeric units and a minority (~5-10 mol%) of polar monomeric units, typically acids such as -COOH. The acid groups can be neutralized with cations to create ionic species such as -COO-Na+ in the case of a Na-neutralized carboxylic acid. Because these ionic species are considerably more polar that the surrounding matrix, there is a driving force for the ionic species to microphase separate and form ionic aggregates although the resulting morphologies of ionic aggregates are not well understood. Controlling the morphologies of ionomers is the primary goal of the proposed research and the first step to developing both a predictive theoretical model of these materials and a robust understanding of their structure-property relationships. These ionic aggregates act as physical crosslinks to toughen the polymer and lead to both current industrial applications (chemically resistant thermoplastics, tough coatings, permselective membranes for fuel cells, and food packaging materials) and a variety of potential technological applications (e.g. protection against chemical warfare). These complex polymeric materials spur scientific interest, because (1) these amphiphilic materials have ionic interactions that mimic biological macromolecules, (2) ionomers are readily available with a wealth of chemistries that includes amorphous and semicrystalline polymers and a range of cations, and (3) high-resolution analytical tools are now available to investigate the interdependencies of chemistry, processing, morphology and properties. Winey's scanning transmission electron microscopy (STEM) studies of ionomers since 1998 provide a valuable foundation to the proposed research in which Winey endeavors to identify the materials parameters and processing conditions that have the most substantial influence on the ionomer morphologies. The proposed work seeks to uncover reliable trends in the ionomer morphology in order to provide fundamental understanding of these complex materials. As Winey determines how the various materials and processing parameters influence the ionomer morphology they will be able to control the ionomer morphology. Two hallmarks of the proposed experimental plan are (1) the use of model materials, that is materials designed to address specific scientific questions, and (2) the use of multiple characterization tools including SAXS, FT-IR, and, in particular, a range of analytical electron microscopy (AEM) methods. Industrial, academic and military scientists have scientific interest in both the proposed research about ion-containing polymers and the development of AEM characterization tools for polymers. Winey will collaborate with the Lehigh Microscopy School to ensure that electron microscopists take full advantage of the AEM methods that are used within the proposed work to investigate complex, chemically heterogeneous polymeric materials. In addition, Winey will continue to both serve as a faculty co-advisor to the Society of Women Engineers on Penn's campus and hold an annual panel about opportunities for graduate studies and academic careers in engineering.