Construction of ultrathin and microporous polyesteramide nanofilms for efficient organic solvent nanofiltration (OSN) using diacyl chloride.

The integration of high permeability and exceptional selectivity, thereby overcoming the conventional "trade-off" effect, remains a persistent challenge for the practical implementation of organic solvent nanofiltration (OSN) membranes. Herein, at the molecular level of design, we utilized the 5,5′-diamino-2,2′-biphenol (amino-BIPOL) and diacyl chloride as IP monomers to prepare OSN membranes with high perm-selectivity. The amino-BIPOL, a contorted biphenol molecule with four reactive sites, serves as a molecular-level unit to hinder efficient packing of polymer chains and induce the formation of interconnected micropores in the resulting polyesteramide layers. By employing diacyl chloride terephthaloyl dichloride (TPC) and isophthaloyl dichloride (IPC) as the oil-phase cross-linker, two kinds of TFC membranes were prepared. The resulting membranes both present smooth surface morphology, with ultrathin and high microporous selective layer allowing for efficient mass transfer. Specifically, the methanol permeance of amino-BIPOL/TPC and amino-BIPOL/IPC membrane reaches up to 15.1 and 15.6 LMH/bar, while maintaining a molecular weight cut-off (MWCO) value of 300 and 373 Da, respectively. Overall, this work illustrates the different oil-phase cross-linkers will result in diverse nanofilm microstructure and thus with distinct perm-selectivity properties, offering new insights for the design and modification of advanced OSN membranes. [Display omitted] • Amino-BIPOL and diacyl chloride were used to prepare TFC OSN membranes by IP method. • The membranes present high micropores and ultrathin characteristics. • Two oil phase cross-linker result in nanofilms with diverse cross-linked network. • The optimal membrane shows methanol permeance of 15.1 LMH/bar and MWCO of ∼300 Da. [ABSTRACT FROM AUTHOR]