Overview
Our group focuses on developing an improved understanding of the molecular interactions that govern thermodynamics and transport across complex polymer-solution interfaces. These physics are the foundation of polymer-based technologies that offer exciting opportunities to address humanity’s pressing need for clean water and sustainable energy by performing advanced separations (e.g., membrane processes). Despite industrialization of membrane processes, relatively few polymer chemistries are currently deployed, with these materials being ill-equipped to address next-generation separations due, in part, to a lack of solute specific selectivity.
To guide the rational design of new polymeric materials and separation processes, our group combines characterization with elements of modeling and materials synthesis in order to develop mechanistic frameworks that can predict molecular transport rates as a function of fundamental polymer and solution properties:
We develop and perform experiments that measure fundamental properties quantifying membrane performance (e.g., solubility, diffusivity, permeability, conductivity, selectivity, etc.). We apply this data to i) improve theories and models describing transport across polymers and ii) design new polymeric materials for advanced separations and transport processes.
Our current research areas are briefly highlighted below. We are broadly interested in polymer science, membrane separations, transport phenomena, and thermodynamics, and are always open to building collaborations and exploring new applications!
The Role of Polymer Chemistry and Electrostatics on Aqueous Ion Separations
Critical strides in the 20th century optimized membranes to desalinate seawater with remarkable energy-efficiency. Looking forward, membranes will serve a central role in emerging aqueous separations (e.g., critical mineral recovery and wastewater treatment). These applications operate on a distinct paradigm than desalination, often requiring precise separation of ions from varying feed solutions that contain complex mixtures of solutes at wide-ranging ionic strengths. The inability of state-of-the-art membranes to distinguish between ions with similar physiochemical properties (e.g., valence, size, and hydration) necessitates new membrane materials with ion specific separation properties tailored to a given process. To develop basic knowledge connecting ion-ion selectivity with polymer chemistry and electrostatic interactions, we are conducting studies of hydrated polymers challenged by ions relevant to water treatment, resource recovery, and electronic waste recycling (e.g., Li+, Na+, Mg2+, Co2+, Ni2+, Cl–, SO42-).
Some particular interests include: i) sorption and diffusion of ion pairing electrolytes, ii) cation specific separations using polymers containing cation-coordinating ligands, and iii) high-throughput methods to measure sorption and diffusion of single and multi-component solutions.
Engineering Ion-Exchange Membranes for Emerging Electrolysis Systems
Reducing our carbon footprint while meeting growing demands for energy is critical to sustaining humanity. Electrochemical production of valuable chemicals and fuel via electrolysis processes (e.g., CO2 reduction cells) offers one strategy towards this goal. Beyond efficient redox reactions, electrolysis relies on an ion-conducting membrane that permeates a specific redox active ion, while largely rejecting other ionic species and product molecules. Conventional membranes used today do not exhibit this intricate combination of transport properties, which can limit device utility. To define structure-property relationships that will enable the development of next-generation electrolysis membranes with desirable properties, we are studying transport across polymeric interfaces that model the conditions that ion-exchange membranes (IEMs) are exposed to during electrolytic operation.
Some particular interests include: i) multi-component sorption and diffusion of alcohol-water-ion mixtures, ii) effects of ion speciation and polymer hydration on ion selectivity, and iii) resolving organic liquid transport mechanisms in IEMs via in-operando measurements.