Extremes of Macromolecular Charge Pairing Motif in Polyelectrolyte Complex Coacervates

Part 1: Non-Technical Summary Nature has used biopolymers, such as DNA, proteins and polysaccharides, to make materials with extraordinarily sophisticated properties and functions. In many of these materials, opposite charges associate to join various biopolymers together into larger structures. Inspired by Nature, this project will investigate how charge associations in synthetic polymers may be used to create new materials for use in adhesion, biomedicine, health, and materials science. To advance the science as broadly as possible, three subtopics closely connecting synthetic- and bio-polymers will demonstrate that the placement of charge influences a host of essential materials properties, such as strength, toughness and potential use in biomedical science. The project will develop the workforce at both the undergraduate level, with paid internships at a new company developing lithium batteries, and the graduate level, with intensive mentoring in state-of-the-art technology and use of National facilities, such as Oak Ridge National Lab. Student creativity in materials design and synthesis will be supplemented by a series of Tech Startup seminars to accelerate the translation of discoveries into the market. The work carried out under this award will benefit biotechnology. Part 2: Technical Summary Polymers carrying a multitude of charges, termed polyelectrolytes, may be positive or negative, and are found widely in the synthetic (for example, in personal care products) and natural (for example, DNA) worlds. The crosslink is a central concept in macromolecular science. Crosslinks between molecules control the properties of both synthetic and living soft materials. These crosslinks may be permanent, to maintain long-term structure, or dynamic, to allow changes in morphology. Physical crosslinks, such as electrostatic charge pairs between oppositely-charged building blocks, are reversible. Polyelectrolyte complexes, PECs, form spontaneously when oppositely-charged polyelectrolytes are mixed. While the dependence of PEC properties on the number and type of charge have been extensively studied, the placement of charge relative to the backbone has not. Charges in polyelectrolytes are usually located on pendant groups dangling from the polymer backbone. In the proposed work, the properties of new PECs from polyelectrolytes bearing charge integral to, versus far from, the polymer backbone will be contrasted. An important class of naturally-occurring polyelectrolyte, polyphosphate, will be used to gain further understanding of how charge pair crosslinks and backbone dynamics are interrelated. By using these extreme contrasts in the arrangement of charge, the proposed work will provide important insight on how charge placement and charge density offer transformative structural parameters in designing new synthetic PECs and will deepen the understanding of the liquid-like coacervates that abound in living systems. 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. NSF Award ID: 2610481 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Joseph Schlenoff | Institution: Florida State University, TALLAHASSEE, FL | Award Amount: $560,862 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2610481 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2610481.html