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

Project: Research project

Project Details


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.

Effective start/end date9/15/192/28/22


  • National Science Foundation: $215,000.00


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