ChE Seminar Series: Relationship between Structural Properties and Microscopic Diffusion of Molecules in Membranes and Porous Solids by High Field NMR

Sergey Vasenkov, Ph.D.

Date(s) - 10/31/2023
9:00 am - 10:00 am

HPNP 1404


Sergey Vasenkov, Ph.D.
Department of Chemical Engineering
University of Florida

Title: Relationship between Structural Properties and Microscopic Diffusion of Molecules in Membranes and Porous Solids by High Field NMR

Abstract: Molecular diffusion plays a key role in a larger range of chemical engineering applications, including separations, catalysis, as well as development of sensors and supports intended for controlled release or capture of liquid or gas molecules. Many systems of practical relevance have heterogeneous structure resulting in different rates of diffusion in different local environments of these systems. In addition to knowledge of diffusion of single component gases or liquids in these systems, also understanding of diffusion of mixtures of gas and liquid molecules is of practical importance. In this seminar I will present some recent examples of our diffusion studies in such systems using pulsed field gradient (PFG) NMR at high magnetic fields up to 17.6 T. The high field allows acquiring sufficiently large signal-to-noise ratios from guest molecules even when a low-sensitivity C-13 resonance or small sample sizes required for magic angle spinning (MAS) measurements are used. The examples will include diffusion in metal organic frameworks (MOFs), MOF/polymer hybrid membranes, ionomers (viz. synthetic polymers with ionic properties), and mesoporous silicas. The uniqueness of studies with mesoporous silicas is related to an ability of independent measurements of the diffusion of gas and liquid molecules inside the pores where one component was liquid (hexane or hexadecane), and the second was gas (methane or ethane) dissolved in the first liquid component.

Bio: Dr. Sergey Vasenkov is a professor at the Department of Chemical Engineering, University of Florida. His research mostly focuses on detailed understanding and optimization of mass diffusion on microscopic length scales of displacements in a variety of materials, including microporous membranes, porous catalysts and ionic liquids. He completed his Ph.D. in physics and mathematics at the Institute of Chemical Kinetics and Combustion (Novosibirsk, Russia) in 1994. Dr. Vasenkov was a postdoctoral fellow at Lawrence Berkeley National Laboratory, Berkeley from 1995 to 1998 and was a member of the teaching and research staff of the Department of Physics and Earth Sciences at the Leipzig University, Germany from 1998-2006. He was awarded the Habilitation degree (i.e. advanced Doctorate degree, which includes a lecturing qualification) by Leipzig University in 2003. Dr. Vasenkov joined the University of Florida in 2006 as an assistant professor. Since joining the UF he has received a number of awards including NSF CAREER award, the 2009-2010 UF College of Engineering Teacher of the Year Award, the 2017-2018 UF Herbert Wertheim College of Engineering Teacher of the Year Award, and German Science Foundation (DFG) Mercator Fellowship in 2018.