Synthesis and characterization of interfacially polymerized polyamide thin films

A homologous series of thin film composite (TFC) membranes was made by interfacial polymerization (IP) of trimesoyl chloride (TMC) and m-phenylenediamine (MPD). Membrane flux and rejection as well as the chemical and mechanical properties of the unsupported IP film were evaluated as a function of monomer concentration. The surface characteristics of the IP films were determined using electron-spectroscopy-for-chemical-analysis (ESCA) and contact angle measurements, and the mechanical properties were obtained using pendant drop mechanical analysis (PDMA) and surface profilometry. Results indicate that the TMC concentration has a more pronounced effect on the IP film properties than the MPD concentration. Higher TMC concentration leads to a pronounced increase in the IP film thickness and surface hydrophilicity. In contrast, the thickness increase is smaller and surface hydrophilicity decreases when the MPD concentration is increased. Water flux was determined to depend mainly upon the IP film thickness and surface hydrophilicity whereby these two parameters have counterbalancing effects. Consequently, the decrease in water flux with increasing MPD concentration is pronounced, but a corresponding increase in the TMC concentration has a smaller effect. These studies provide an improved basis for understanding the factors that govern TFC membrane performance.