Highly Permeable Reverse Osmosis Membranes via Molecular Layer-by-Layer Deposition of Trimesoyl Chloride and 3,5-Diaminobenzoic Acid.

We present a series of polyamide membranes synthesized via molecular layer-by-layer (mLbL) deposition of trimesoyl chloride (TMC) and 3,5-diaminobenzoic acid (BA). These membranes exhibit superior NaCl rejection compared to previously reported TMC-BA membranes prepared via interfacial polymerization, with the improved performance of the mLbL films attributable to higher cross-link density facilitated by the stepwise deposition process in good solvents. We compare the TMC-BA series with membranes synthesized from TMC and -phenylenediamine (MPD), a conventional reverse osmosis membrane chemistry. At the minimum thickness capable of 90 % NaCl rejection, mLbL TMC-BA membranes exhibit 50 % greater water permeance than mLbL TMC-MPD.