Membranes are useful in a wide variety of separations, including water purification and desalination, removal of greenhouse gases from industrial emissions, and prevention of product crossover in electrochemical cells.  Dr. Miller is interested in the structure/property relationships that govern the transport of small solutes—including gases, ions, and small-molecule organics—through polymeric membranes.  These relationships become particularly complex in the presence of solute mixtures, where solute-solute interactions and/or solute-membrane interactions can affect transport, such as in the case of membrane plasticization.  Furthermore, understanding interfacial phenomena affecting membrane transport, such as ion sorption/exclusion and foulant deposition, is of interest.

Dr. Miller’s research in JCAP focuses on the characterization of polymeric membranes for use in electrochemical CO2 reduction cells.  These membranes are responsible for permitting charge carrier transport from electrode to electrode while minimizing product crossover that reduces device efficiency.  Measurement of ion and CO2 reduction product transport through various membranes forms the cornerstone of Dr. Miller’s research program.  Commercial and newly-synthesized experimental membranes are characterized.  Polymer characteristics—such as charge density, crystallinity, and morphology—are tuned to develop an understanding of how transport is affected.  Dr. Miller is also developing new measurement techniques for accurate analysis of transport in solute mixtures.