Polyamide-based thin film composite membranes represent the state-of-the-art materials for seawater desalination. Based on the concept of reverse osmosis (RO), the ultrathin and highly crosslinked aromatic polyamide selective layer facilitates separation of water from solutes via differences in permeability. While interfacial polymerization is the typical method to producing commercial polyamide membranes, this approach yields selective layers that are highly depth-heterogeneous with limited control over film thickness and interfacial roughness, characteristics that limit the ability to optimize permselectivity.In this presentation, we describe molecular layer-by-layer assembly (Figure 1), which is a brick-and-mortar approach that enables the rational design of polyamide selective layers with control over the film thickness, roughness, and chemical composition at the molecular level. We demonstrate that molecular layer-by-layer is capable of producing well-defined ultrathin films of various types of aromatic polyamides. More importantly, we show that these molecular layer-by-layer assembled polyamides function as water desalination membranes with water flux and fouling resistance that is far superior to interfacially polymerized polyamide membranes.

Brick-and-mortar approach to fabricating water desalination membranes

247th National Meeting (2014)

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