As interest in decentralized water treatment technologies that enable localized water reuse grows, the development of nanofiltration (NF) as a complementary process to reverse osmosis has emerged. However, NF membranes that overcome the tradeoff between selectivity and permeability, that expand the range of molecules that can be selectively separated, and that resist the detrimental effects of fouling must be developed in order to realize the potential of NF-based processes. One approach for overcoming the permeability-selectivity trade-off is through the development of membranes with better controlled pore sizes and pore size distributions. In fact, the performance of NF membranes based on self-assembled materials is already pushing the limits of these size-selective separation mechanisms. Therefore, many researchers are considering approaches that move beyond improved control of size-selective separation mechanisms. In this regard, the functionality lining the pore walls of NF membranes offers another means through which to increase selectivity without sacrificing permeability. Specifically, due to the small pore size of NF membranes, electrostatic interactions and van der Waals forces affect solute permeation dramatically. This feature presents several opportunities for the introduction of functionalities that enable molecular separations based on chemical factors. In regards to fouling, a multitude of antifouling chemistries have been identified, yet introducing these functional chemistries without disrupting the nanostructure of the membranes and in a manner that is consistent with state-of-the-art membrane manufacturing processes remains a challenge. In this talk, we will discuss how inkjet printing and click chemistry can 1) functionalize membrane chemistries in a precise manner on time scales consistent with roll-to-roll manufacturing, 2) enable the chemical-patterning of membranes in order to access emergent transport mechanisms, and 3) generate multifunctional membranes capable of resisting the detrimental effects of fouling while exhibiting high valence selective separations. Through these examples, we will demonstrate that membranes that are functionalized post-assembly using additive manufacturing approaches provide a scalable platform that can be tailored to myriad separations for the purification and conservation of water resources.

Opportunities for expanding membrane functionality through additive manufacturing

2019 Spring National Meeting

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