Thin-film composite polyamide membranes, are the basis for modern commercial reverse osmosis (RO) membranes. These membranes are created through interfacial polymerization (IP) involving a trifunctional acid chloride (e.g., trimesoyl chloride, TMC, dissolved in an organic solvent) and a difunctional amine (e.g., m-phenylenediamine, MPD, dissolved in water). While these membranes excel in water permeability and salt rejection, their high surface roughness and uneven distribution of polar groups contribute to scaling/fouling of the membrane and makes structure-property relationships difficult to achieve.
GW Researches have developed a novel rinse-free molecular layer-by-layer (mLbL) deposition technique that enables the fabrication of polyamide-based reverse osmosis membranes with low surface roughness and tunable membrane thickness. The polymer deposition on the surface is controlled effectively by decreasing the solution concentration and volume, minimizing the presence of unreacted monomer after each cycle. These polyamide-based membranes display water flux and salt rejection comparable to a commercial brackish water membrane. Our research highlights the potential for tailoring the mLbL process towards large scale manufacturing of RO membranes with tunable thickness and low surface roughness.
Figure. Schematic representation of the modified layer-by-layer (mLbL) process and film thickness measurement.
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