The successful realization of thin film composite (TFC) organic solvent nanofiltration (OSN) membranes with high permeability and small solute selectivity for solute–solute separation to purify drugs in complex solution environments remains challenging in the pharmaceutical industry. Here, we present the preparation of high cross-linked TFC OSN membranes via interfacial polymerization (IP) utilizing phlorotannin, a plant-derived biomass phenolic compound, as a promising aqueous phase monomer. Benefiting from the presence of multiple cross-linking sites and twisted rigid structure in phlorotannin, nanofiltration membranes with excellent molecular selectivity and solvent permeability were successfully fabricated. This allowed for straightforward separation and purification of active pharmaceutical ingredients from intermediates. The membranes demonstrated remarkable stability over extended periods of operation and adaptability to a diverse array of solvent environments, making them a highly promising option for use in fine chemicals, biopharmaceuticals, and other fields.
Jianghai Long,Xiansong Shi,Zhe Zhang,Tong Ju,Qinghua Liu,Yong Wang
Crystalline covalent organic framework (COF) membranes with well-defined architectures are critical for sustainable separation technologies. However, conventional synthetic routes relying on straightforward monomer condensation often fall short in producing COF membranes with superior crystallographic order. Here, the ambient-condition synthesis of COF-LZU1 polycrystal monolayer membranes is reported via imine-exchange chemistry. By employing aniline as a monofunctional modulator, the crystallization pathway is shifted from direct imine formation to a kinetically regulated imine-exchange process. This modulation suppresses rapid nucleation and mitigates both intra- and intercrystalline defects, yielding structurally distinctive membranes composed of polycrystal monolayers. The method is compatible with various substrates and enables facile fabrication of COF-LZU1 polycrystal monolayer separation membranes. Membrane morphology and crystallinity can be fine-tuned by adjusting the volumes of aniline and acetic acid. The optimized COF-LZU1 membrane performs exceptional molecular sieving in osmosis-driven separation, achieving efficient purification of pharmaceuticals from their precursors with operational stability over 500 h. This work provides a powerful strategy for developing unambiguously crystalline COF membranes and reveals the significance of crystallinity in advancing COF-based membrane technologies.
Conjugated microporous polymers (CMPs), characterized by permanent microporosity and exceptional stability, represent a promising class of materials for next-generation molecular-sieving membranes. Nevertheless, high-quality CMP membranes with well-designed pore architectures remain inaccessible due to the challenges associated with processing these materials. Herein, we report a molecular layer deposition (MLD) process for the sequential assembly of 3-butylthiophene and 3,3′-bithiophene in situ on commercial nanofiltration substrates under MoCl 5 oxidation. The precise MLD strategy enables the integration of flexible alkyl chains to soften the CMP backbone while preserving its intrinsic microporosity. The resulting composite CMP membranes enabled high-resolution purification of nanoscale species with molecular weights as low as 270 g mol −1 while exhibiting exceptional long-term stability during continuous operation over 150 h. We also proved that thus-prepared CMP membranes exhibit great potential for the purification and recovery of high-value pharmaceuticals and catalysts. This work highlights the potential of MLD as a versatile strategy for fabricating CMP membranes and grafting internal functionalities, enabling high-resolution separation in liquid systems.
Tianci Feng,Xiansong Shi,Tong Ju,Jianghai Long,Qinghua Liu,Ming Liu,Yong Wang
Covalent organic frameworks (COFs), with their regularly organized structures and solvent resistance, offer distinct advantages for constructing liquid-phase separation membranes. In nearly a decade of development, research has mainly focused on two-dimensional (2D) COFs, which yet give insufficient molecular selectivity due to inherent large pores. Here, we present a mixed-dimensional strategy of growing three-dimensional (3D) COFs on 2D COFs to build bilayered membranes for efficient organic solvent nanofiltration (OSN). The pores of 3D COFs interlace with those of 2D counterparts, resulting in a subnanoporous composite. We develop this 3D-/2D-COFs composite as robust membranes with a nanoscale thickness. The optimal bilayered membrane yields ethanol permeance of 12.2 L m −2 h −1 bar −1 with a molecular weight cutoff as low as ∼400 g mol −1 , surpassing conventional COF-based OSN membranes. Importantly, the designed 3D-/2D-COFs membrane exhibits stable separation performance and excellent sieving ability to discriminate molecular mixtures. This exceptional molecular selectivity ultimately allows the separation of bioactive pharmaceuticals from impurities through our membrane. Overall, this work provides a design strategy for producing mixed-dimensional COF membranes to advance molecular separation in liquids.
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