Collaborative Research: Fundamental Basis for General Molecular Weight Determination for Ionic Polymers

通过这一奖项，由化学部化学测量和成像计划部分共同资助的高分子、超分子和纳米化学计划将资助宾夕法尼亚州立大学的Ralph H.Colby博士和弗吉尼亚理工学院和州立大学的Louis A.Madsen博士。该团队正在开发新的方法来测量带有附着离子的聚合物的分子量。聚合物是由许多重复单元组成的长链分子，这些单元通过碳-碳键连接在一起。虽然有许多可靠的技术用于准确测定非离子(不带电荷)聚合物的分子量，但将这种方法应用于离子聚合物通常是困难的。离子聚合物是工业上用作水性涂料和水净化技术的增稠剂的一类非常重要的聚合物。一大部分生物分子，包括DNA、RNA、许多多肽和多糖也是重要的离子聚合物的例子。该项目开发了一套新的可靠的技术，可以确定天然和合成离子聚合物的分子量。这些新方法的发展加速了离子导电能源材料和可生物降解材料的发展，使社会受益。这样的研究活动培养了高分子科学方面的学生，为未来在聚合物(塑料)行业就业做准备。材料和劳动力的发展是保持美国工业全球竞争力的核心。这项研究集中在开发四种方法，利用易于测量的离子聚合物半稀溶液的动态性质来获得数平均分子量。每种方法都依赖于校准测量的特定组合，因此每种方法都可以直接确定溶液中的链数密度，从而确定该溶液中聚合物的数均分子量。这四种方法各自的优点是它们对盐浓度不敏感(因为盐可能具有挑战性，甚至不可能被去除)，并且具有变革的潜力，能够在使用非常少的样品的情况下对离子聚合物进行常规的相对分子质量测定。预计这些方法将迅速被采用，从而使聚电解质和离聚体的开发迅速增长，以适应无数的应用。该项目中理论和实验方法的发展和验证进一步影响了聚合物科学的物理基础，并使人们能够对离子聚合物的性质有新的理解。虽然这项研究主要是使用合成聚合物进行测试和开发，但也承诺能够对透明质酸、肝素、DNA和RNA等生物聚合物的分子量进行常规表征。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。

With this award, the Macromolecular, Supramolecular and Nanochemistry Program with partial co-funding from the Chemical Measurement and Imaging Program in the Division of Chemistry is funding Dr. Ralph H. Colby from Pennsylvania State University and Dr. Louis A. Madsen from Virginia Polytechnic Institute and State University. The team is developing new methods for measuring the molecular weight of polymers that have attached ions. Polymers are long-chain molecules consisting of many repeating units that are linked together through carbon-carbon bonds. While there are many firmly established techniques used to accurately determine the molecular weight of nonionic (uncharged) polymers, applying such methods to ionic polymers is usually difficult. Ionic polymers are a very important class of polymers used by industry as thickeners in water-based paints and coatings and in water purification technologies. A large fraction of biological molecules, including DNA, RNA, many polypeptides and polysaccharides are also examples of important ionic polymers. This project develops a novel set of robust techniques that determine molecular weights for both natural and synthetic ionic polymers. Development of these new methodologies benefits society by accelerating the development of ion-conducting energy materials and biodegradable materials. Such research activities train students in macromolecular sciences for future employment in polymer (plastics) industries. The development of both materials and workforce are central to keeping US industries globally competitive.This research is focused on developing four methods that utilize easily measured dynamic properties of semidilute unentangled solutions of ionic polymers to obtain the number-average molecular weight. Each method relies on specific combinations of calibrated measurements so that each one directly determines the number density of chains in solution and thus the number-average molecular weight of the polymers in that solution. These four methods each have the advantage that they are insensitive to salt concentration (since salt can be challenging or even impossible to remove) and have the transformative potential to enable routine molecular weight determinations for ionic polymers, while using very little sample. Quick adoption of these methods is anticipated, allowing rapid growth of the development of polyelectrolytes and ionomers to suit a myriad of applications. Development and validation of the theory and experimental methods in this project further impact the physical underpinnings of polymer science and enable new understanding of ionic polymer properties. While mainly being tested and developed using synthetic polymers, this research also promises to enable routine characterization of molecular weight for biopolymers such as hyaluronic acid, heparin, DNA and RNA.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.