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Compared with traditional methods for elaborately tailoring the active layer of thin-film composite (TFC) membranes, this study focused on building novel substrates for potential applications in developing organic solvent nanofiltration (OSN) membranes. One kind of "three-parts" hierarchically structured interface with nanospheres and macro surface pores was successfully prepared via Michael addition and Schiff's base (M&S) reactions between N-(2-aminoethyl)-3-aminopropyl triethoxysilane (NAE-A) and glycerite (a natural polyphenol) in the aramid substrate. The thickness was reduced to sub10 μ m with the aid of the high-speed spin coating process coupling nonsolvent-induced phase separation (HSSC-co-NIPS) method. The composition characterization results demonstrated the introduction of glycerite, and the reactions occurred in/on the substrate. Scanning electron microscopy (SEM) images clearly showed that the sub10 μ m substrate contained a "three-level" hierarchically structured interface that included: (1) a "stalk-like" structure; (2) glycerite-NAE-A silane (GNAS) nanospheres; and (3) the substrate surface. These phenomena also resulted in better surface hydrophilicity. All types of organic solvents, including harsh solvents, such as tetrahydrofuran (THF) and N,N-dimethylformamide (DMF), had stable permeability within the substrate, as did apolar n -hexane and isopar™ G. Therefore, the as-prepared TFC OSN membrane, which had an extremely short polymerization time, retained broad-spectrum solvent stability and had the highest solvent permeance in acetonitrile (24.5 ± 0.4 L m−2 h−1·bar−1). In addition, the resultant TFC membrane almost completely rejected the popular macrolide antibiotic azithromycin (AZM, 748.98 g mol−1) in ethanol, which is used to treat COVID-19. Image 1 • Sub10 μm macroporous substrates were prepared via the HSSC-co-NIPS method. • The natural polyphenol glycerite and NAE-A were adopted first in membrane development. • The "three-parts" hierarchically structured interface could be distinctly observed. • Short polymerization (20 s) time offered excellent performance. • AZM could be almost completely purified and concentrated in EtOH with the membrane. [ABSTRACT FROM AUTHOR]

Active layers with outstanding organic solvent nanofiltration (OSN) performances were designed novelly by adopting host-guest (HG) interaction to realize adamantane structure immobilization. During the fabrication process, β -cyclodextrin (β -CD) served as the "host" while adamantylamine/adamantanemethylamine (AMA/AMmA) worked as the "guest". Stechiometrical experiment results demonstrated that one half molar ratio of the "guest" to the "host" molecular (1.0%, w/v) led to the best OSN performance. The successful immobilization of adamantane structure was verified by XPS , FT-IR and EDX results, and the adamantane immobilized membrane showed weakened "nodule-like" pattern and reduced surface roughness values compared with the control membrane. Acetone, for the first time, was proposed as the activation solvent for enhancement of OSN performance. After acetone activation, the morphology and topography of the adamantane immobilized membranes seldom changed but their pure methanol (MeOH) flux were quintupled (29.0 ± 2.6 L m−2 h−1) and the rose bengal (RB) removed from MeOH reached to 98.2 ± 0.1%. Those HG complexes also resulted in the reduction of molecular weight cut-off (MWCO) values from 466.6 Da to 436.9 and 428.4 Da of PCA10 1/2 + and PCAm10 1/2 +, respectively. Besides, the PCAm10 1/2 + demonstrated excellent OSN performances in the long-term operation of active pharmaceutical ingredients (APIs) concentration of clarithromycin (CLA)/acetone. Novel designed active layer immobilized adamantane structure with outstanding stability and membrane performances for organic solvennt nanofiltration (OSN). Image 1 • Host-guest chemistry was firstly utilized in OSN membrane development. • Adamantane structure was successfully immobilized into the active layer. • Activation of the OSN membrane using pure acetone was firstly proposed. • The mechanism of experimental errors of MWCO values was illuminated. • Outstanding performance in the potential application of API concentration was made. [ABSTRACT FROM AUTHOR]