Collaborative: The Polyelectrolyte-Ionomer Transition in Polymers

合作：聚合物中的聚电解质-离聚物转变

• 批准号: 0705745
• 负责人: Ralph Colby
• 金额: --
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0705745&HistoricalAwards=false
• 关键词: Collaborative; Polyelectrolyte; Ionomer; Transition; Polymers

Technical SummaryPolymers with charges on their backbones, along with neutralizing small molecule counterions, are termed polyelectrolytes or ionomers. The chief distinguishing factors between these different terms is the state of aggregation of the charges: in the case of polyelectrolytes, a significant fraction of the counterions are dissociated from the chain and can move freely through the system. In contrast, in the case of ionomers, nearly all counterions are strongly condensed onto the chain, and additionally these neutral charge pairs may form neutral aggregates of many ion pairs. While the attractiveness of these materials comes from the fact that they selectively transport cations alone, this is mitigated by the fact that the presence of isolated aggregates can make ion conduction a very slow transport process. The goal is to understand the factors which control the ion pairing to form isolated dipoles, and the further factors which drive these dipoles to self-assemble into aggregates. The dielectric constant of a relatively nonpolar polymer will be changed by adding a high dielectric constant solvent and vary temperature over a wide range. Aggregation will be studied directly through STEM and both SAXS and SANS. Less direct techniques will also be used, such as mechanical rheology and DSC, where self-assembly of ion pairs into aggregates is associated with a signature that is akin to a glass transition and rheology strongly depends on whether the counterions are free, paired or clustered. Recently developed dielectric spectroscopy methods will determine free ion content and mobility in ionomers, directly assessing the extent of ion pair formation. These studies will be complimented by computer simulations, employing Monte Carlo and Molecular Dynamics methods. Non-Technical SummaryThe intellectual merit of this research will be an improved understanding of ion-pairing and ion-pair clustering, culminating in the development of a new model that fully details the transition from polyelectrolyte to ionomer. Such ion-containing polymers are of considerable interest since they have been proposed for use in actuators, fuel cell membrane electrode assemblies and for the cation conduction medium for advanced batteries. Hence, this research should facilitate polymer design for actuators, fuel cells and batteries. Materials development in the energy field is expected to play a very important role in the future of the United States economy and way of life. Graduate students trained in this 'energy materials' arena will be in enormous demand in both US industry and academia. PSU and Columbia have superb undergraduates and research motivates them to attend graduate school (14/23 of our undergraduate researchers have gone on to graduate school in science and engineering over the past 10 years) with many current undergraduates interested in 'energy materials'

技术摘要聚合物的骨架上有电荷，以及中和小分子柜台，称为聚电解质或离子体。这些不同术语之间的主要区别因素是指控的聚合状态：在聚电解质的情况下，相反的很大一部分与链条分离，并且可以通过系统自由移动。相反，就离子体而言，几乎所有的柜台都强烈凝结到链上，此外，这些中性电荷对可能形成许多离子对的中性聚集体。尽管这些材料的吸引力源于它们仅有选择地运输阳离子的事实，但由于孤立的聚集体的存在可以使离子传导成为非常缓慢的运输过程，因此可以减轻这一事实。目的是了解控制离子配对以形成孤立偶极子的因素，以及将这些偶极子自我组装成聚集体的更多因素。 相对非极性聚合物的介电常数将通过在较大范围内添加高介电常数溶剂和变化来改变。聚集将直接通过STEM和SAX和SAN进行研究。 还将使用较少直接的技术，例如机械流变学和DSC，其中离子对自组装成骨料的自组装与类似于玻璃过渡的签名和流变学在很大程度上取决于对立面是免费，配对还是群集。最近开发的介电光谱法将确定离子体中的自由离子含量和迁移率，从而直接评估离子对形成的程度。这些研究将通过使用蒙特卡洛和分子动力学方法的计算机模拟来称赞。 非技术总结这项研究的智力优点将是对离子对和离子对聚类的一种改进的理解，最终是在一个新模型的开发中，详细介绍了从多电解质到电离体的过渡。 这种含离子的聚合物引起了极大的兴趣，因为已提议用于执行器，燃料电池膜电极组件以及高级电池的阳离子传导介质。 因此，这项研究应促进执行器，燃料电池和电池的聚合物设计。 预计能源领域的材料开发将在美国经济和生活方式的未来中发挥非常重要的作用。 接受过“能源材料”领域的培训的研究生将在美国和学术界都有巨大的需求。 PSU和哥伦比亚拥有一流的本科生和研究激励他们上研究生院（过去十年来，我们的本科研究人员中有14/23个继续从事科学和工程学研究生院），许多目前对“能源材料”感兴趣的本科生