Physical Chemistry Seminar: Professor Paul Cremer, Pennsylvania State University

Physical Chemistry Seminar: Professor Paul Cremer, Pennsylvania State University (Host: Steven Boxer)

**This seminar is available for in-person attendance.**

"Exploring the Binding of Ions to Polymers in Aqueous Salt Solutions"

About the Seminar

Hofmeister series chemistry has been a focus of both fundamental and industrial interest since it was first discovered over 130 years ago. It can be shown that a wide variety of physical phenomena follow a recurring rank ordering for both cations and anions when water, organic molecules and salts are mixed. Examples include the hydrophobic collapse and aggregation of macromolecules, the turnover rate of enzymes, the pickling of cucumbers, and even the transfer of charge between ice particles in a lightning storm. Using a combination of spectroscopic techniques, thermodynamic measurements as well as simulations, it is now possible to elucidate key molecular level details of Hofmeister series behavior. In this presentation, the solubility of thermoresponsive polymers in the presence of salts will be discussed. The results show that weakly hydrated anions bind along polymer chains in locations where the hydrogen bonding is most greatly disrupted. Curiously, this makes shorter oligomers less soluble compared to longer polymers possessing the same chemical constituents in NaSCN, NaI, or NaClO4 solutions. Moreover, weakly hydrated anions interact more strongly than cations with uncharged polymer chains. In fact, metal cations rarely come to the polymer/water interface without being accompanied by counter anions.

About the Speaker

Paul S. Cremer is the J. Lloyd Huck Chair in Natural Sciences at the Pennsylvania State University where he holds appointments in both the Department of Chemistry and the Department of Biochemistry and Molecular Biology. Prof. Cremer received his undergraduate degree from the University of Wisconsin – Madison (1990) and his Ph.D. from the University of California - Berkeley (1996) working with Prof. Gabor A. Somorjai as his thesis advisor.  He spent two years as the Irving S. Sigal Postdoctoral Fellow at Stanford University in the laboratory of Steven G. Boxer before starting his independent research career at Texas A&M University in 1998. He stayed at A&M for over 14 years, where he was named Distinguished Professor in 2012. The following year his laboratory moved to Penn State. He is a fellow of the American Association for the Advancement of Science as well as of the American Chemical Society. In 2017, he was named a Langmuir Lecturer by the ACS.  His group works at the cross-roads of physical chemistry, biological chemistry, materials science, and analytical chemistry.

Image Courtesy of Penn State Chemistry Department