CAREER: Using electrostatic interactions to guide microstructure and mechanical properties in block polyelectrolytes

非技术概述：聚电解质是含有带电化学基团的聚合材料，已在许多重要技术中得到应用。这些包括分离膜（例如，气体或水净化），能量储存和收集装置（例如，锂离子电池，离子交换膜或有机光伏）以及生物医学应用材料。在这些应用中使用的聚合物需要在纳米尺度上组织和组装，这在聚电解质系统中通常难以预测和控制。这种限制通常源于与控制聚电解质合成有关的困难以及文献中出现的聚合物特性的不一致。因此，调查文献排除了对多电解质行为的经验预测。CAREER项目将采用模块化合成策略，可重复控制聚电解质中带电基团的数量和类型，从而实现聚合物特性与特定应用标准之间的相关性，例如纳米级组装特性和机械性能。此外，与聚合物科学有关的教育材料将分发给当地K-12教师，他们也将接受培训，将基于问题的学习纳入他们的课程。此外，该项目将吸引本科生和研究生，并突出聚合物科学对周围公共社区的重要性和影响。技术总结：由于合成平台、分子量分布和报道的绝对分子量的变化，通过文献调查建立聚电解质的经验结构-性能设计规则是不切实际的。最近的理论工作已经确定离子熵、离子溶解度和分子范围内的静电相互作用是协同影响嵌段聚电解质形态的关键参数。因此，本项目将采用活阴离子聚合法制备分子量可调、分子量分布窄的双嵌段四聚体（即两个嵌段，四个单体）前驱体。随后，前驱体将进行正交聚合后功能化，以在不同电荷密度下可控地引入各种电荷类型（例如，磺酸盐、铵离子和三唑离子的组合）。这种方法使电荷类型、电荷密度和主链组成与离子溶剂化、反离子熵和静电内聚以及最终与微相分离和流变性质的实验关联成为可能。因此，这项工作的结果将以经验设计规则的形式展示策略，补充最近的理论结果，以设计基于反离子熵、离子溶剂化和聚电解质材料中的远程库仑相互作用的特定应用性能。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY: Polyelectrolytes are polymeric materials containing electrically charged chemical groups and have been implemented in a number of important technologies. These include separations membranes (e.g., gas or water purification), energy storage and harvesting devices (e.g., Li-ion batteries, ion exchange membranes, or organic photovoltaics), and materials for biomedical applications. The polymers utilized in these applications require organization and assembly at the nanometer scale, which is often difficult to predict and control in polyelectrolyte systems. This limitation often stems from difficulties related to controlling polyelectrolyte synthesis as well as inconsistencies in polymer characteristics that appear in the literature. As a consequence, surveying the literature precludes an empirical prediction of polyelectrolyte behavior. This CAREER project will utilize a modular synthetic strategy to reproducibly control the amount and type of charged groups within the polyelectrolyte, thus enabling correlations between polymer characteristics and application-specific criteria, such as nanoscale assembly features and mechanical properties. Additionally, educational materials related to polymer science will be delivered to local K-12 teachers, who will also be trained in integrating problem-based learning into their curricula. Furthermore, this project will engage undergraduate and graduate students, and highlight the importance and impact of polymer science to the surrounding public community.TECHNICAL SUMMARY:Establishing empirical structure-property design rules for polyelectrolytes through a survey of the literature is impractical due to the variations in synthetic platforms, molecular weight distributions, and absolute molecular weights reported. Recent theoretical work has identified ion entropy, ion solubility, and molecular-range electrostatic interactions as key parameters that synergistically influence the morphology of block polyelectrolytes. Therefore, this project will employ living anionic polymerization to prepare a diblock tetrapolymer (i.e., two blocks, four monomers) precursor with tunable molecular weight and narrow molecular weight distributions. Subsequently, the precursor will undergo orthogonal post-polymerization functionalization to controllably introduce various charge types (e.g., combinations of sulfonate, ammonium, and triazolium ions) at various charge densities. This approach enables experimental correlation of charge type, charge density, and backbone composition to ion solvation, counterion entropy, and electrostatic cohesion and ultimately to microphase separation and rheological properties. Thus, the outcome of this work will demonstrate strategies, in the form of empirical design rules that complement recent theoretical outcomes, to design application-specific performance based on counterion entropy, ion solvation, and long-range Coulombic interactions in polyelectrolyte materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.