Controlling Ionomer Morphologies

该研究将使用模型材料和各种分析电子显微镜（AEM）方法研究含离子聚合物的形态，特别是离子聚合物。离聚体是随机共聚物，大多数是非极性单体单元和少数极性单体单元（~5-10摩尔%），通常是酸，如-COOH。酸基团可以与阳离子中和以产生离子种类，例如在na中和羧酸的情况下-COO-Na+。由于这些离子种类比周围的基质极性大得多，因此存在离子种类微相分离并形成离子聚集体的驱动力，尽管所产生的离子聚集体的形态尚不清楚。控制离聚体的形态是提出的研究的主要目标，也是发展这些材料的预测理论模型和对其结构-性质关系的强大理解的第一步。这些离子聚集体充当物理交联，使聚合物变韧，并导致当前的工业应用（耐化学热塑性塑料，坚韧涂层，燃料电池的过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的兴趣，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)离聚体很容易与丰富的化学物质结合，包括非晶和半晶聚合物以及一系列阳离子，(3)高分辨率的分析工具现在可以用来研究化学，加工，形态和性质的相互依赖性。自1998年以来，Winey对离聚体的扫描透射电子显微镜（STEM）研究为提出的研究提供了有价值的基础，其中Winey努力确定对离聚体形态影响最大的材料参数和加工条件。提出的工作旨在揭示离子形态的可靠趋势，以提供对这些复杂材料的基本理解。当Winey确定各种材料和加工参数如何影响离聚体形态时，他们将能够控制离聚体形态。提出的实验计划的两个特点是：(1)使用模型材料，即设计用于解决特定科学问题的材料，以及(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含离子聚合物的拟议研究和聚合物AEM表征工具的开发都有科学兴趣。Winey将与利哈伊显微学院合作，确保电子显微镜学家充分利用AEM方法，这些方法在拟议的工作中用于研究复杂的、化学上不均匀的聚合物材料。此外，威尼将继续担任宾夕法尼亚大学校园女性工程师协会的教师联合顾问，并每年举行一次关于工程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.