Unifying Principles for the Design and Manufacture of Chemically-Patterned Polymeric Membranes

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Due to their ability to control molecular transport, membranes are essential components of modern separations (e.g., water treatment) and sensing (e.g., glucose monitoring) processes. As their application has advanced, a need for more selective membranes has emerged. In this regard, engineered systems that take inspiration from biological membranes provide one route toward realizing more selective membranes. To bring this new paradigm to fruition, processes for patterning the surface chemistry of membranes in a manner that is consistent with proven manufacturing methods are needed. This award leverages recent advances in the fields of nanostructured polymers, membrane manufacturing, and ink-jet printing to address fundamental scientific issues related to the production of charge-patterned mosaic membranes. The fundamental knowledge to be gained has broad implications for manufacturing of multifunctional membranes that address critical challenges needed to ensure the well-being and prosperity of the American people. For example, by changing the formulation of the reactive inks, unique functions are possible leading to the development of therapeutic medicine or chemical and biological threat detectors. This project is multidisciplinary and involves polymer chemistry, transport phenomena, and nanostructured materials. It helps revolutionize the manufacturing landscape of the U.S. by training the next generation of interdisciplinary scientists and engineers.Charge-patterned mosaic membranes consist of discrete positively-charged and negatively-charged domains that traverse the membrane thickness. They are used to initiate this line of inquiry because their ability to transport salts selectively emerges directly from their patterned chemistry. Despite their potential utility in separations and sensing applications, the selective transport mechanisms of these membranes are poorly understood. This critical knowledge gap is a direct result of challenges related to manufacturing chemically-patterned membranes. In particular, morphological changes induced during the harsh chemical treatments required to introduce charged functionality have hampered prior efforts to generate this class of membranes. Here, this engineering opportunity is met by integrating nanostructured copolymer substrates that are amenable to functionalization using 'click' reactions with ink-jet printer-mediated deposition of reactive inks. This research enables the systematic design and manufacture of charge-patterned membranes. It studies the fabrication of self-assembled copolymer membrane substrates that are molecularly-engineered to enable chemical-patterning using ink-jet printing. It evaluates the performance of charge-patterned membranes in model chemical separations to correlate membrane performance with pattern design and composition. The project advances the use of additive manufacturing within the field of membrane science and delivers a versatile membrane technology that offers improved selectivity in traditional and emerging applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.