Collaborative Research: Robust General Methods for Determination of Polyelectrolyte Molecular Weight and Polydispersity

合作研究：测定聚电解质分子量和多分散性的稳健通用方法

• 批准号: 2203753
• 负责人: Louis Madsen
• 金额: $ 28万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2203753&HistoricalAwards=false
• 关键词: Collaborative; Research; Robust; General; Methods

With the support of the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry, Professors Ralph H. Colby from Pennsylvania State University and Louis A. Madsen from Virginia Polytechnic Institute and State University are developing methods for measuring the molecular weight of polyelectrolytes. Polyelectrolytes are long chain macromolecules whose repeating units contain an electrolyte group. This group dissociates in water, making the polymer charged. Similar to salts, polyelectrolyte solutions are electrically conductive. Many biological and artificial macromolecules are polyelectrolytes and find application in biomedical, technological and industrial science. Some notable examples include implant coatings, controlled drug delivery, water-purification systems, food coatings and cosmetics. While there are many developed techniques used to accurately determine the molecular weight of neutral polymers, methodologies for ionic or charged polymers are comparatively scarce. The principal reason is the lack of adequate theoretical approaches to describe polyelectrolyte properties and very complex behavior in solution. This research aims to provide a basis for molecular weight determination for ionic polymers having a single type of charge (polyanions or polycations), including both natural and synthetic systems. The methods being developed here, if successful, could significantly accelerate the design and synthesis of polyelectrolytes. Additionally, the development and validation of the proposed theoretical and experimental methods is expected to further impact the physical underpinnings of polymer science and enable new understanding of ionic polymers. This work also promises to facilitate the characterization of molecular weight for many biopolymers such as hyaluronic acid, heparin, DNA and RNA. Training opportunities and exposure to polymer chemistry concepts and techniques will be provided to graduate and undergraduate students at both institutions. Research activities will also be utilized to recruit students into macromolecular programs and prepare them for careers in polymer science. Outreach activities at Virginia Tech will include presentations that highlight concepts in ionic polymer gels, macromolecular chain motions and energy storage. This hands-on K-12 outreach program seeks to broaden thinking and encourage elementary and high school students to consider pursuing science and technology careers. The ongoing REU (research experiences for undergraduates) program at Pennsylvania State University will be leveraged to include recruitment of students from underrepresented groups. Polyelectrolytes are increasingly used in alternative energy technologies, engineered human tissues, drug delivery, and a host of other applications. A critical barrier to wider development and application of polyelectrolytes lies in the extreme effort required to characterize their absolute molecular weight. Furthermore, the balance between strong electrostatic repulsions along each chain with the entropic penalty for stretching the chain is delicate and not yet understood in detail, making simple models only work under specific circumstances. This project will focus on a detailed scaling theory for polyelectrolyte behaviors in solution that underlies four distinct methods (using measured terminal modulus, relaxation time, chain diffusion, correlation length, and viscosity) for measuring number-average molecular weight (Mn). These four methods will employ measurements by solution rheology, X-ray scattering, and NMR diffusometry. A strong emphasis will be placed on developing a toolbox that establishes well-defined operating strategies and parameter spaces for practical applications of these methods in the semi-dilute unentangled regime. The scope of measurements will include a wide array of polyelectrolyte chemistries. Furthermore, a technique to reliably quantify polydispersity for polyelectrolytes using the diffusion-based molecular weight determination method by NMR spectroscopy is under development. Lastly, the utility of the methods for analyzing neutral polymers will also be explored. If successful, this research will not only provide a toolbox of experimental techniques that others can use, but also a theoretical framework for scaling relationships to describe data that translate into molecular weight and polydispersity, parameters of critical importance in characterizing charged polymers.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.

在化学系中的大分子，超分子和纳米化学（MSN）计划的支持下，宾夕法尼亚州立大学的拉尔夫·H·科比教授和来自弗吉尼亚州理工学院和州立大学的路易斯·A·麦德森正在开发用于测量多电解质分子体重的方法。 聚电解质是长链大分子，其重复单元包含电解质基。 该组在水中解离，使聚合物充电。 与盐相似，聚电解质溶液是导电性的。 许多生物学和人工大分子是聚电解质，并在生物医学，技术和工业科学中找到应用。 一些值得注意的例子包括植入涂料，受控药物输送，水纯化系统，食物涂料和化妆品。 尽管有许多已发达的技术用于准确确定中性聚合物的分子量，但离子或带电聚合物的方法学相对较少。 主要原因是缺乏描述聚电解质特性和解决方案中非常复杂的行为的足够理论方法。 该研究旨在为具有单一类型的电荷（多仿皮或多阳离子）（包括天然和合成系统）的离子聚合物的分子量测定提供基础。 如果成功的话，这里开发的方法可以显着加速聚电解质的设计和合成。 此外，预期所提出的理论和实验方法的发展和验证将进一步影响聚合物科学的物理基础，并能够对离子聚合物进行新的了解。 这项工作还有望促进许多生物聚合物（例如透明质酸，肝素，DNA和RNA）的分子量表征。 培训机会以及对聚合物化学概念和技术的接触将为这两个机构的研究生和本科生提供。 研究活动还将用于招募学生参加大分子计划，并为聚合物科学的职业做好准备。 弗吉尼亚理工大学的外展活动将包括在离子聚合物凝胶，大分子链运动和能源存储中突出概念的演讲。 这个动手的K-12外展计划旨在扩大思维，并鼓励小学和高中生考虑从事科学和技术职业。 宾夕法尼亚州立大学正在进行的REU（本科生的研究经验）计划将利用以包括代表性不足的群体的学生招募。 聚电解质越来越多地用于替代能源技术，工程人类组织，药物输送和许多其他应用中。多电解质的更广泛发展和应用的关键障碍在于表征其绝对分子量所需的极端努力。此外，沿着每个链的强静电排斥与拉伸链条的熵惩罚之间的平衡是微妙的，尚未详细理解，使简单模型仅在特定情况下起作用。 该项目将重点介绍解决方案中聚电解质行为的详细缩放理论，该理论是四种不同的方法（使用测量的末端模量，松弛时间，链扩散，相关长度和粘度）来测量数字平均分子量（MN）。 这四种方法将通过解决方案流变，X射线散射和NMR扩散法进行测量。 将非常重视开发一个工具箱，该工具箱建立了定义明确的操作策略和参数空间，用于在半脱水的未键入状态中这些方法的实际应用。 测量范围将包括各种各样的聚电解质化学。 此外，通过基于扩散的分子量测定方法确定通过NMR光谱来可靠地量化聚电解质的多分散性的技术正在开发中。 最后，还将探索用于分析中性聚合物的方法的实用性。 如果成功，这项研究不仅将提供其他人可以使用的实验技术工具箱，还将提供一个理论框架来描述将数据转化为分子重量和多分散性的数据，这是表征带电聚合物至关重要的参数。该奖项颁发了NSF的法定任务，并通过评估范围的概念来反映出了对支持者的支持和概念的支持。

项目成果

Determining the Molecular Weight of Polyelectrolytes Using the Rouse Scaling Theory for Salt-Free Semidilute Unentangled Solutions

• DOI: 10.1021/acs.macromol.2c01007
• 发表时间: 2022-08
• 期刊: Macromolecules
• 影响因子: 5.5
• 作者: A. Han;Veera Venkata Shravan Uppala;D. Parisi;C. George;Benjamin J. Dixon;Camila Denise Ayala;Xiuli Li;L. Madsen;R. Colby

Synthesis and Characterization of Multi-Reducing-End Polysaccharides

• DOI: 10.1021/acs.biomac.3c00104
• 发表时间: 2023-06-01
• 期刊: BIOMACROMOLECULES
• 影响因子: 6.2
• 作者: Zhai，Zhenghao;Zhou，Yang;Edgar，Kevin J.
• 通讯作者: Edgar，Kevin J.