| NSF Org: |
CHE Division Of Chemistry |
| Recipient: |
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| Initial Amendment Date: | July 6, 2020 |
| Latest Amendment Date: | December 23, 2021 |
| Award Number: | 1954373 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Colby Foss
cfoss@nsf.gov (703)292-5327 CHE Division Of Chemistry MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | August 1, 2020 |
| End Date: | October 31, 2024 (Estimated) |
| Total Intended Award Amount: | $450,000.00 |
| Total Awarded Amount to Date: | $450,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3 RUTGERS PLZ NEW BRUNSWICK NJ US 08901-8559 (848)932-0150 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
610 Taylor Rd Piscataway NJ US 08854-3925 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | CSD-Chem Strcture and Dynamics |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
The overarching goal of the joint project by Professors Margulis (U. of Iowa) and Castner (Rutgers), funded by the NSF Chemical Structure and Dynamics Mechanisms (CSDM-A) program, is to understand how the molecular structure of a special class of liquids determines their viscosity. Viscosity is a measure of how well a liquid flows (for example, pure honey is more viscous than water). Professors Margulis and Castner are specifically interested in Ionic Liquids (ILs). ILs are unique materials; like table salt they are solely composed of positive (cationic) and negative (anionic) species, but unlike table salt, which is a solid at ambient conditions, they are liquids at room temperature. The reason why understanding and controlling the viscosity of ILs is important relates to their many possible applications as lubricants, as solvents for industrial processes or in advanced battery materials. On a microscopic length scale these liquids are complex, with networks of positive and negative charges separated by uncharged domains. The research team is using a battery of techniques including computer simulations, nuclear magnetic resonance, as well as X-ray and neutron scattering to attack these challenging questions. Researchers in this study range from undergraduate level students to graduate students to postdoctoral fellows, each contributing and gaining unique experiences on experimental and theoretical tools.
One of the most pressing questions about ionic liquids is how to control their viscosity for specific applications. These liquids are structurally and dynamically heterogeneous with networks of charge being the stiffer component, and it is the relaxation with time of the charge alternation pattern within these that is directly linked to viscosity. The research team is seeking to understand how this process of ?charge-blurring? occurs. For this, they are using theoretical calculations and molecular dynamics simulations as well as X-ray scattering, neutron scattering techniques that allow for temporal resolution of the dynamics of the different liquid structural motifs, and NMR techniques. The ultimate goal is to derive a predictive and pictorial view of what causes the viscosity for specific ILs. The broader impacts of the study are manifold; they include supplying the community of researchers working on ILs with an understanding of how viscosity might be controlled for different scientific and technological applications. In addition to providing formal training for graduate students and post-doctoral fellows, the project is providing research experience for undergraduate students, including some from Queensborough Community College.
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.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
During this grant period our collaborative team focused on the relation between structure and structural dynamics, as well as the viscoelastic relaxation of selected room-temperature ionic liquids. Ionic liquids are particularly interesting because, just like rock salt or table salt, they are composed solely of ions, but as opposed to rock salt they have relatively low melting points and are candidates for several technologies. Structure in our studies is often studied using molecular dynamics simulations from a computational perspective, and synchrotron scattering or NMR from an experimental perspective. In the relevant intermolecular region, scattering of ionic liquids often shows three peaks or features associated with (i) correlations of ions or parts of them that are adjacent, (ii) correlations of positive and negative charges, and (iii) the correlations at intermediate range that are related to polar-apolar separation across ions. We often found in our studies that of these three motifs, it is charge alternation that is the most closely related to the viscoelastic relaxation. On a more technical aspect, we find that the charge alternation subcomponent of the dynamic structure function S(q,t) provides the most clear approach to study this, and that the viscoelastic relaxation falls between that of the fastest and slowest structural motifs described earlier. We also introduced NMR relaxation analysis as a method to study the dynamics of these motifs. The articles published during this period help advance our overall understanding of how ions move in ionic liquids and how this motion correlates with different structural motifs that naturally occur in these fascinating systems.
Last Modified: 05/02/2025
Modified by: Andrew J Nieuwkoop
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