Water, Salt, and Temperature Effects in Polyelectrolyte Complexes and Multilayers

第一部分： 本研究涉及含有电荷的聚合物的超薄膜，其被称为“聚电解质”。 它们可以形成多层膜和分子复合物，并且在从生物医学到温度响应材料的应用中具有重要意义。 这样的聚电解质经历不寻常的“玻璃熔融”或软化转变，其性质和时间依赖性还没有很好地理解。 在这里，PI建议使用实验技术来评估这种转变的直接起源，这些技术将在分子水平上对其进行探测。这将提供一个坚定的观点，如何过渡和其动力学相互关系方面的温度，水和电荷所产生的不同的盐。该项目特别强调盐的类型，其中检查了具有不同大小，电荷和水相互作用的各种盐。一个可能的结果是温度、水和盐之间的统一关系，因为它控制着转变。这将是非常重要的，因为这些新知识将允许微调与这些材料相关的转变温度和物理性质，最终导致可能的新的先进应用。拟议研究的一个主要内容是教育，指导和培训未来一代掌握科学技能的多样化工人，并在本地和在线向公众提供科学推广。第二部分： 提出实验来研究在水合的双金属络合物和多层中观察到的热转变的性质。如果成功，这个项目将揭示水在热转变中的作用。可能的结果包括实验验证的作用，聚阴离子-水的相互作用中的热转变，水和盐的热转变的关系，和时间-温度-盐-水叠加的证据。所提出的方法集中在石英晶体微天平与耗散，差示扫描量热法，电化学阻抗谱，温度控制的傅里叶变换红外光谱和动态力学分析。拟议的项目包括四项活动：（1）研究水-聚（苯乙烯磺酸盐）的相互作用，作为温度的函数，（2）探索和确定水和其他溶剂的作用，（3）检查和理解盐的作用，以及（4）确定可能的水-盐的连接和对与过渡相关的动力学的影响。 拟议工作的教育部分包括对研究生和本科生的培训和指导，以及在当地和通过NAE EngineerGirl网站进行外联。

PART 1: NON-TECHNICAL SUMMARY This research concerns ultra-thin films of polymers containing electrical charges, which are known as "polyelectrolytes". They can be formed in multilayers and molecular complexes and are of interest in applications ranging from biomedical to temperature-responsive materials. Such polyelectrolytes undergo an unusual "glass-melt" or softening transition whose nature and time-dependence are not well understood. Here the PI proposes to evaluate the direct origin of this transition using experimental techniques that will probe it on a molecular level. This will provide a firm view of how the transition and its dynamics interrelate with regard to temperature, water, and charges arising from different salts. This project places a unique emphasis on salt type, where a broad range of salts with varying size, charge, and water interactions are examined. One possible outcome is a unified relationship among temperature, water, and salt as it governs the transition. This will be of significant importance because this new knowledge will allow fine-tuning of the transition temperature and the physical properties associated with these materials, ultimately leading to possible new advanced applications. A major element of the proposed research is to educate, mentor, and train a future generation of diverse workers skilled in science as well as to offer science outreach to the general public both locally and online. PART 2: TECHNICAL SUMMARY Experiments are proposed to investigate the nature of the thermal transition observed in hydrated polyelectrolyte complexes and multilayers. If successful, this project will shed new light on water's role in the thermal transition. Possible outcomes include the experimental verification of the role of polyanion-water interactions in the thermal transition, water and salt relationships with the thermal transition, and evidence of time-temperature-salt-water superpositioning. The proposed approach centers on quartz crystal microbalance with dissipation, differential scanning calorimetry, and electrochemical impedance spectroscopy, temperature-controlled Fourier transform infrared spectroscopy and dynamic mechanical analysis. The proposed project is comprised of four activities: (1) investigate water-poly(styrene sulfonate) interactions within polyelectrolyte multilayers as a function of temperature, (2) explore and determine the role of water and other solvents, (3) examine and understand the role of salt on the transition, and (4) determine possible water-salt connections and effects on dynamics associated with the transition. Educational components of the proposed work include training and mentoring of graduate and undergraduate students, as well as outreach locally and through the NAE EngineerGirl website.