After selecting a material for a particular application, a detailed higher order structure appropriate for the application typically must be created. Fibers are popular in our group for both membrane and sorbent applications. For barriers, flat sheet and other shapes are also studied to understand how basic transport properties are altered by addition of small molecules or by specialized processing of the starting material. In the membrane and barrier cases, spinning an asymmetric hollow fiber with a skin on the outside or on the lumen layer is often a key goal. The intervening wall of such fibers also can be quite different for a membrane versus a sorbent application; nevertheless, in all cases, the control of nanoscopic morphology is a feature to which we pay great attention.
Beside successfully creating a functional structure with ability to serve as a membrane, sorbent or barrier, our group considers how to generate these structure at rates that can be scaled up to a practical level. This practical processing aspect is a special focus of our group. Without reliable means of characterizing local morphologies at the scale significant to a penetrant, it is difficult to engineer the morphology. This need has increasingly drawn our attention toward improving characterization methods for asymmetric media as we push the existing state of the art of membrane and sorbent formation technology. Indeed, many times, we use diffusion and sorption to probe the properties of the morphology or device in a way that would not be feasible even using advanced spectroscopy or imaging.