Topologically Frustrated Dynamics and Memory in Polyelectrolyte Systems

非技术性高分子由带电荷的单体组成的大分子在所有生物中普遍存在，并继续催化现代水基材料的配方。要从根本上理解这种分散在电解质水溶液中的带电大分子的行为仍然是一个挑战。挑战的根源在于这样一个事实，即这些分子并不是作为单独的分子本身发挥作用，而是在整个集体系统中非常远的距离内相互关联。因此，带电大分子的性质充满了挑战，没有足够的概念框架来理解其丰富的现象学。事实上，形成对这种强相关大分子的基本理解仍然是物理和生物科学中最困难的课题之一。然而，除了使几十年来积累的丰富现象学合理化外，这种基本的理解对于成功设计用于分离科学、高吸水性产品、药物输送、水基导体和记忆器件的新材料至关重要。PI建议建立一个基本的理解，即带电的大分子如何在电解液溶液中或凝胶中移动，或如何通过拥挤引起的中间势垒从一个区域移动到另一个区域，以及如何在水基系统中赋予大分子记忆效应。除了推动带电大分子领域的发展，拟议的活动还包括大力支持多样性和培训新一代学者，使他们能够参与到未来价值数十亿美元的水基材料工业中。技术总结PI建议通过结合光散射、中子散射、阻抗谱、流变学、单分子电泳、统计力学、场论和几种模拟技术来研究聚电解质动力学、聚电解质凝胶动力学、拓扑受阻非扩散动态、凝聚凝胶复合材料和水凝胶中的大分子记忆的实验和理论发展。具体地说，该建议涉及(A)拓扑受挫的非扩散聚合物动力学状态及其与势垒和旋转机制的边界，(B)凝聚凝胶复合材料中的相图、结构和分级动力学，(C)凝胶复合材料的导电性，以及(D)水凝胶中的记忆。这一建议旨在了解严重非平衡条件下的带电水凝胶复合材料，并发现新的概念模型，以研究聚电解质在带电聚合物体系中的传输和记忆。对这类重要材料行为的基本了解将有助于设计具有更大社会效益的新型水基聚合物材料。在这一具有挑战性的研究领域对研究生和博士后的培训也是拟议活动的重要组成部分。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYMacromolecules made of monomers carrying electrical charges are ubiquitous in all living organisms and continue to catalyze formulations of modern water-based materials. A fundamental understanding of the behavior of such charged macromolecules dispersed in aqueous electrolyte solutions continues to be a challenge. The origin of the challenge lies on the fact that these molecules do not behave on their own as individual molecules, but they are correlated over very large distances spanning the whole collective system. As a result, the properties of charged macromolecules are full of challenges without adequate conceptual framework to understand their rich phenomenology. In fact, formulation of a fundamental understanding of such strongly correlated macromolecules remains one of the most difficult subjects in physical and biological sciences. Yet, such a fundamental understanding is crucial to successfully design new materials for separation science, highly water-absorbent goods, drug delivery, water-based electrical conductors, and memory devices, in addition to rationalizing the rich phenomenology already accumulated over many decades. The PI proposes to formulate a fundamental understanding of how electrically charged macromolecules move around in an electrolyte solution, or inside a gel, or from one region to another through intervening barriers due to crowding, and how to endow macromolecular memory effects in water-based systems. In addition to advancing the field of charged macromolecules, the proposed activities include strong support of diversity and training a new generation of scholars to enable their future participation in the multi-billion dollar industry of water-based materials.TECHNICAL SUMMARYThe PI proposes experiments and theoretical developments to investigate polyelectrolyte dynamics, polyelectrolyte gel dynamics, topologically frustrated non-diffusive dynamical state, coacervate gel composites, and macromolecular memory in hydrogels, by combining light scattering, neutron scattering, impedance spectroscopy, rheology, single molecule electrophoresis, statistical mechanics, field theory, and several simulation techniques. Specifically, the proposal addresses (a) topologically frustrated non-diffusive polymer dynamical state and its boundaries with the entropic barrier and reptation regimes, (b) phase diagrams, structure and hierarchical dynamics in coacervate gel composites, (c) electrical conductivity of gel composites, and (d) memory in hydrogels. This proposal is aimed at understanding charged hydrogel composites under severe non-equilibrium conditions, and discovering new conceptual models for polyelectrolyte transport and memory in aqueous charged polymer systems. A fundamental understanding of the behavior of this important class of materials will help to design novel water-based polymeric materials with enhanced benefits to society. Training of graduate students and postdocs in this challenging research area is also an important component of the proposed activity.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.