Water is critical to the health and security of our nation. And as our population expands and water scarcity becomes a reality, we as a people need to think creatively on how we safeguard access to clean water. The manufacturing of today’s state-of-the-art membranes for water purification is based on 1970’s technology of interfacial polymerization of the selective layer directly a porous support. In this, polymerization occurs at the interface of two immiscible liquids, where one liquid is wicked into the porous support. Over the next 40 years, this membrane technology has slowly evolved through an Edisonian, trial-and-error approach. This process makes extremely thin (100’s nm) selective membranes, but these membranes are difficult to characterize due to high roughness and large-scale heterogeneity. Thus, our fundamental understanding of how these membranes work is insufficient to allow rational design of next-generation membranes.<br/><br/>In 2011, we proposed a paradigm shift in how these types of membranes are fabricated, where the selective layer is created layer-by-layer through a reactive deposition process. In this approach, we employed a solution-based deposition process where we sequentially and repeatedly layered each reactive monomer onto a solid substrate. By doing so, we created membranes that are smooth, tailorable, and exceptionally thin (10’s nm). But there are still many challenges yet to overcome, from membrane support design to membrane characterization. In this talk, I will describe our efforts to meet these challenges through judicious experimental design and materials selection, and I will share how some of our measurements have challenged our thinking in how these materials selectively pass water while rejecting salt.

Advanced membrane characterization enabled by molecular layer-by-layer deposition of polyamides

2019 Spring National Meeting

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