Tailored dendrimer interlayer based on Marangoni convection for high-performance reverse osmosis membranes

Abstract

Advanced reverse osmosis (RO) membranes for desalination, typically thin-film composite (TFC) membranes, have emerged as a prominent research direction to combat water scarcity. The substrate properties, such as the amine monomer adsorption capacity, are considered important for the interfacial polymerization (IP) process. Herein, inspired by Marangoni convection, a tailored dendrimer interlayer based on the plasma-treated polyethylene substrate was developed via the in-depth modification driven by surface tension gradient to precisely adjust the substrate properties. In addition, sodium dodecyl sulfate (SDS) was introduced as an additive to synergistically improve the desalination performance, and its role was reinvestigated. The quantitative experiments of amine monomer adsorption show that the substrate with in-depth modification possesses enhanced adsorption capacity. Therefore, massive amines can be enriched at the substrate surface, which can erupt and react violently in IP, thereby forming a polyamide layer with thick apparent thickness and abundant nanovoids. The RO membrane after optimization exhibits 99.19 % of rejection to NaCl and 3.87 L m−2 h−1 bar−1 of permeance, which shows good competitiveness compared with the advanced polymer-based RO membranes. This work provides constructive suggestions for the screening of interlayers to RO membranes and the application of polyethylene-based TFC membranes.