46578-UFS
Investigating the Mobility and Thermodynamics of Mixed Ionic Liquid - Water Systems
The scientific goal of the sabbatical research was to obtain combined experimental data on various physico-chemical properties as a function of water-ionic liquid composition, to obtain a comprehensive picture about the dynamics, intermolecular interactions and aggregation propensity present in mixed ionic liquid-water solvents. These data would also help Dr. Stark from the host institution in her on-going work on condensation reactions in ionic liquid media by elucidating the role of the liberated water in these reactions.
Since Dr. Stark's group had already a fair amount of kinetic data using the ionic liquid [bmim][MeSO3] we started our investigations with this ionic liquid, including batch comparison between two different vendors. The melting point of [bmim][MeSO3] is near 80oC. Considerable experimental challenges needed to be overcome mainly to prevent composition changes during the course of measurements on the binary ionic liquid – water systems. Indeed, knowledge on physical chemical data for this particular ionic liquid is nearly absent in the literature. These experimental challenges were overcome, and additional measurements were also carried out on [emim][MeSO3] (mp. 35oC) mixtures with water as a function of composition and temperature.
The PI supervised one Master student,
Mrs. Grit Sauer, from the host institute who focused on the viscosity and
surface tension measurements. The PI himself conducted all of the calorimetric as
well as the electric conductivity measurements. As for the NMR diffusion
measurements, while the host institute had access to NMR instrumentation
through a neighboring institute, the time requirements of the experiments
turned out to be prohibitively long. It was therefore decided that the PI would
shorten the stay in
The combined data will be thoroughly analyzed and disseminated in due course. Several initial findings can be reported at this point. Foremost, we did not observe any profound trend changes near equimolar compositions, as the results from Dr. Stark's kinetic studies suggested. The composition dependency expressed in mass% shows simpler functions with often only slight non-linearities than when expressed in mole fractions. Only the diffusion and somewhat the conductivity data indicated a slope change near equimolar compositions (~9 mass%). Impurities in the ionic liquid had varying effects on the measurements. For example, they resulted in essentially no differences for the conductivity measurements but in substantial changes for the surface tension and calorimetric measurements.
Other positive outcomes of the
sabbatical stay in
Given the opportune availability of a large number of ionic liquids in Dr. Stark's laboratory, the PI also further explored the presence of extremely stable ion pairs for ionic liquids in low dielectric media, as he had previously discovered these for [emim][NTf2] (J. Sol. Chem. 2004, 33, 379-392). This work has lead to a proposal for continued collaborative research which was submitted for funding to the RUI program of the National Science Foundation.
As a beginning of what we hope to become a vibrant exchange of student researchers, a semester long research stay at SUNY Brockport is planned for doctoral student Mr. Martin Sellin. Mr. Sellin has been conducting chemical shift studies as part of his doctoral thesis research and will have the opportunity to conduct more advanced NMR experiments under the guidance of the PI. He will thus receive hands-on training on how to use a modern NMR instrument, an educational experience which is presently not available to chemistry students at FSU Jena. In preparing for Mr. Sellins research stay, the PI finds much internal support for these plans. In particular, the Office of Residential Life at SUNY Brockport is offering free housing. In turn, Mr. Sellin will serve on a new SUNY Brockport residential life program called “Math Science Learning Communities” which intends to improve science student learning outcomes and to promote learning interactions among science students.
The Pi's expertises have also proved to be very helpful for several other ongoing research projects at the host institute during his sabbatical research stay at FSU Jena. As a result, there have been already three co-authored publications. The PI was also invited to write a book chapter on surfactants in green chemistry. Thanks to the sabbatical leave, the PI was able to accept this invitation and has submitted the manuscript in late May 2008.
Overall, the PI had the opportunity to delve deep into the theoretical and practical aspects of calorimetry, viscosity, surface tension, and conductivity and gained a much more profound understanding of these techniques which he now brings back to the classroom and teaching laboratory at SUNY Brockport.
