Regulating the interfacial polymerization process toward high-performance polyamide thin-film composite reverse osmosis and nanofiltration membranes: A review

Polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) and nanofiltration (NF) membranes are the core elements for the membrane-based desalination technologies. Nowadays, the preparation of TFC membranes is dominated by the interfacial polymerization (IP) process, of which the reaction system is composed of the substrates and the two phases (aqueous and organic phases). For the TFC RO and NF membranes, the improved permselectivity, desirable for both industry and academia, can be realized by regulating the IP process, which is usually neither process-intensive nor time-consuming. In this review, the representative methods of regulating the IP process are outlined and divided into two categories: the reformation of substrates and the development of aqueous and organic phases. Additionally, this review analyzes the similarities of these methods and, based on our knowledge, discusses the possible reasons underlying the contradictory conclusions in the mutually independent studies. At the end of each category, the imperative discussion on the direction of further research is proposed. It is anticipated that this review can offer guidance for further regulating the IP process, thereby improving the permselectivity of TFC RO and NF membranes.