(619c) Controlling Reverse Osmosis and Nanofiltration Membrane Properties Using Electrospray Printing

Polyamide is the most commonly used polymer materials platform that is used for nanofiltration (NF) and reverse osmosis (RO) membranes today. The success of polyamide membranes on desalination market comes from their ease of fabrication using the interfacial polymerization (IP) method. The reaction between a diamine and an acid chloride, a fast reaction that forms a selective thin layer directly onto a porous support. Although IP produced very useful membranes with very high selectivity and relatively high water permeance, the conventional method fell short on controlling the thickness, morphology, or chemistry directly. Electrospray 3D printing is a recently developed method that can overcome these limitations of conventional IP. It employs electrostatic force induced by electrical potential, creating charged solvent droplets carrying the monomers to be used for membrane formation. Thickness can be adjusted by controlling the amount of deposited monomers and the morphology is smoother. Because the process is additive, it also does not require the high amine excesses that are typically used in IP. While this can save in material costs, it may have unforeseen impacts on polyamide structure and quality. In this work, we explore the parameter space of printing polyamide membranes with different monomers, blends of monomers, and different monomer ratios. The resulting membranes demonstrate unique and independent control of permeance and selectivity to provide membranes with customizable properties.