Effect of Ions on Polymer Properties: Perfluorinated Ionomers, Model Compounds and Ionomer Blends

本研究的目的是研究离子基团对全氟离聚物膜、离聚体溶液和离聚体共混物结构和动力学的影响。计划进行以下实验。首先，他们将研究由极性溶剂膨胀和溶解的膜中聚合物链和反离子的动力学。膜和溶液之间转变的结构变化的可能性将从离聚体浓度的研究中推断出来。实验研究将由链动力学的理论建模来补充。其次，他们将评估基于质子化和氟化表面活性剂的反胶束体系在多大程度上可以用作更复杂的全氟化离聚体的模型化合物。第三，他们建议研究离聚体共混物中的链段动力学和相结构，其中特定的相互作用有望改善共混物组分的相容性。我们建议从聚丙烯酸和无规和嵌段的苯乙烯-丙烯酸共聚物与聚环氧乙烷和聚乙烯吡咯烷酮的共混开始。将研究酸基与各种反离子逐渐中和的效果。第四，我们计划发展电子自旋共振(ESR)成像，作为一种非破坏性的方法，实时研究离聚体和其他复杂聚合物体系的二维和三维扩散过程。我们建议使用ESR(包括多频ESR、双共振和成像)方法来观察顺磁反离子和氚报告分子，用19F核磁共振来观察全氟化链，用2H核磁共振来观察氢化溶剂的动力学，用DSC来将宏观性质与从光谱测量中获得的局部信息关联起来。离聚体是一种两亲性聚合物，含有高达10%的离子基团。在有机聚合物中引入离子基团是改性聚合物性能的重要方法。与不含离子的类似聚合物链相比，这些基团的存在导致聚合物的弹性模量、玻璃化转变温度Tg和各种客体在聚合物中的渗透性发生了显著变化。这些变化大多归因于离聚体中形成相分离的形态，包括电荷集中的离子结构域和主要包括有机主链的非极性结构域。本研究旨在阐明膜的结构。

The objectives of the proposed research is to study the effect of ionic groups on the structure and dynamics of perfluorinated ionomer membranes, ionomer solutions and ionomer blends. The following experiments are planned. FIRST, they will study the dynamics of the polymer chains and counter ions in membranes swollen by, and dissolved in, polar solvents. The possibility of a structural change in the transition between membranes and solutions will be deduced from studies as a function of ionomer concentration. The experimental studies will be complemented by theoretical modeling of the chain dynamics. SECOND, they will assess to what extend reverse micellar systems based on protonated and fluorinated surfactants can be used as model compounds for the more complex perfluorinated ionomers. THIRD, they propose to study segmental dynamics and phase structure in ionomer blends, where specific interactions are expected to improve the miscibility of the blend components. We propose to start with blends of polyacrylic acid and random and block styreneacrylic acid copolymers with poly(ethylene oxide) and with poly(vinyl pyrrolidone). The effect of gradual neutralization of the acid groups with various counter ions will be investigated. FOURTH, we plan to develop electron-spin-resonance (ESR) imaging as a non- destructive method for the study of diffusion processes in real time in ionomers and other complex polymeric systems, in two and three dimensions. We propose to use ESR (including multifrequency ESR, double resonance and imaging) methods for observing the paramagnetic counter ions and deuteriated reporter molecules, 19F NMR to observe the perfluorinated chains, 2H NMR to visualize the dynamics of deuteriated solvents and DSC to correlate the macroscopic properties with the local information obtained from the spectroscopic measurements. Ionomers are amphiphilic polymers that contain up to 10 mole percent of ionic groups. Incorporation of ionic groups in organic polymers is an important method for modifying polymer properties. The presence of these groups causes dramatic changes in the elastic modulus, glass transition temperature Tg and in the permeability of various guests in the polymers, compared to the analogous polymer chains without ions. Most of these changes have been attributed to the formation of a phase-separated morphology in ionomers, consisting of ionic domains where the charges are concentrated, and nonpolar domains that include mainly the organic backbone. This research aims to elucidate the membranes' structure.