Naturally Derived Allylated Gallic Acid for Interfacially Polymerized Membranes

A naturally derived monomer, allylated gallic acid (AG), was herein proposed as a monomer for interfacially polymerized thin-film composite nanofiltration membranes. We investigated the synthesis of the thin-film composite polyester membranes by varying the concentration of the AG monomer and the reaction time with trimesoyl chloride. In addition, we demonstrated the synthesis of a polyesteramide film using a mixture of AG and m-phenylene diamine, although there are a few orders of magnitude differences in their reactivity. While membranes prepared using the classical polyamide process had a water permeance of 0.54 L m-2 h-1 bar-1, the prepared polyesteramide and polyester films had water permeances of 12.3 and 47.6 L m-2 h-1 bar-1, respectively The rejection of dyes was larger than 700 g mol-1 and could be tuned to 327 g mol-1 by changing the chemical composition and reaction time. The retention of inorganic salts followed the order Na2SO4 > MgSO4 ≈ NaCl. Therefore, the membrane performance demonstrates the potential of the phenolic monomer to be integrated into the synthesis of thin-film composite membranes. Besides, the availability of the free allyl group holds potential for further modification and covalent binding onto the surface.