RUI: Solvation in Bulk and Confined Polyethylene Glycol

Suny College At Brockport, Brockport NY

Investigators

Abstract

Water (H2O) dissolves substances like table salt and sugar because the water molecules bind to the salt ions (sodium cations (Na+) and chloride anions (Cl-)) or sugar molecules and therefore break up the solid lattice of these compounds. Other liquids (alcohols, liquid ammonia and liquid carbon dioxide, and many others) can also dissolve chemical substances. An interesting liquid whose solvation properties have not been well-studied is polyethylene glycol (PEG). PEG is different from other common liquids because it is composed of long chains of carbon, hydrogen and oxygen atoms. PEGs are nontoxic and have been successfully used as environmentally benign solvents in chemical synthesis, but we still do not know very much about their solvation properties. In this project supported by the Chemical Structure, Dynamics and Mechanisms-A Program in the Division of Chemistry, Professor Markus Hoffmann, his undergraduate students at the State University of New York, College at Brockport, and international collaborators in Germany are generating new knowledge about PEG as a solvent. Professor Hoffmann’s research program utilizes nuclear magnetic resonance (NMR) spectroscopy, a technique related to the magnetic resonance imaging (MRI) tool used in medicine. NMR spectroscopy provides information about the structure and motions of molecules, as well as interactions between molecules. The Hoffmann laboratory also employs computer simulations of liquid systems. Advanced NMR spectroscopy and computational studies are being done in collaboration with Professors Gerd Buntkowsky and Michael Vogel at the University of Darmstadt in Germany. Professor Hoffmann’s SUNY-Brockport students visit Darmstadt and conduct research there during the summer. The Brockport students are therefore gaining valuable experience not only in the specific subject of the project, but also in international research collaboration. The goal of the project is to develop an understanding of solvation in polyethylene glycol (PEG). To achieve the project goal, the thermophysical properties density, viscosity and self-diffusion coefficient of PEG solutions are being measured to verify force fields used in molecular dynamics (MD) simulations of the same solutions in bulk. Verified force fields are then used for MD simulations of PEG solutions in confinement in mesoporous silica pores with and without surface modification to develop an understanding of confinement effects on solvation and to explore the influence of pore surface modification. The research team will interpret experimental data from several NMR spectroscopic techniques that probe dynamics and molecular interactions of PEG within the pore confinement. The NMR experiments include dynamic nuclear polarization (DNP) enhanced NMR spectroscopy; Solutes of interest include polarizing agents. The findings from the research have the potential to also impact many other research fields because PEGs and “PEGylated” compounds are widely used in pharmaceutical technologies to increase the lifetime of a drug in the circulatory system. Additional broader impacts of the project include the training of undergraduate students, improving the infrastructure of research and research training at SUNY Brockport, and the addition of a meaningful international research experience for the students. 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.