In past research, we demonstrated formation of zeolite-polyamide nanocomposite thin films by interfacial polymerization, which resulted in reverse osmosis (RO) membranes with dramatically improved permeability and interfacial properties when compared to similarly formed pure polyamide thin films. This new concept combines important properties of conventional membrane polymers (flexibility, ease of manufacture, high packing-density modules) with the unique functionality of molecular sieves (tunable hydrophilicity, charge density, pore structure, and antimicrobial capability along with better chemical, thermal, and mechanical stability). Water molecules appear to flow preferentially through super-hydrophilic, molecular-sieve nanoparticle pores, while solute rejection remains comparable to pure polyamide membranes. We believe thin film nanocomposite materials represent a breakthrough in the design of reverse osmosis membranes – introducing new degrees of freedom in membrane design, which could lead to the next generation of high performance reverse osmosis membranes.

More recently we made significant advances in our understanding of why these novel thin film nanocomposite (TFN) membranes seem to out-perform their pure polymer counter-parts. Specifically, we have elucidated several mechanisms during the interfacial polymerization that appear responsible for the improved separation performance and interfacial properties of TFN membranes. A large number of TFN membranes have been hand-cast in the laboratory using an array of molecular sieve nanoparticles synthesized and modified through various means. We have systematically studied a range of parameters that affect membrane performance and interfacial properties, including nanoparticle size, structure, and surface chemistry as well as the chemistry and conditions of the interfacial polymerization process used to form the thin films. We will present results from our rigorous characterization of membrane chemical structure, physical morphology, and membrane interfacial properties through a host of spectroscopic, microscopic and interfacial methods.