Real-Time Characterization of Polymer Membrane Formation and Performance for Energy and Water Applications

Polymer membranes offer promising, energy-efficient solutions for selective transport of species and span applications from wastewater treatment to electrochemical energy storage and conversion. In order to design novel membranes with tailored properties and high selectivity, we need improved fundamental understanding of how membranes interact with ions or other solutes and how membrane morphology impacts their transport. Moreover, translating new membrane materials from the laboratory to manufacturing-relevant processes remains a challenge. This presentation will show how advanced characterization, including synchrotron x-ray probes, can reveal molecular-level insight into membrane-solute interactions, nanoscale membrane morphology, and real-time monitoring of membrane formation and performance. First, this talk will show how spectroscopic and imaging probes can help reveal hydration properties of ions near membrane surfaces. This work provides insight into polymer chemistry to design selective functional groups at the surface to enhance interactions with desired solutes, creating favorable pathways for selective transport across the polymer. Moreover, we will show how chemically-sensitive resonant x-ray scattering can reveal the multi-scale morphology of ion-conducting (ionomer) membranes used in electrochemical energy applications and inform transport properties. Finally, we will demonstrate how in situ x-ray scattering measurements can track membrane formation in real-time during solvent evaporation after casting, which is relevant to industrial membrane manufacturing. These in situ measurements inform how conditions like dispersion composition, drying time, and additives need to be tuned to control the final membrane morphology and performance. Membrane performance, specifically membrane fouling, can be tracked using operando x-ray scattering and diffraction to understand how foulants precipitate during operation or dissolve during cleaning. In general, these studies demonstrate the potential of unique tools, including energy-resolved x-rays and in situ characterization, to probe membrane morphology and interfaces with chemical sensitivity and also unravel manufacturing-relevant dynamic processes.