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Nanofiltration (NF) membranes have aroused great attention in recent years. The most commonly used NF membranes are polyamide (PA) thin-film composite (TFC) membranes based on ultrafiltration membranes. Owing to the high porosity and interconnected pores, electrospun nanofibrous membranes are promising substrates for the fabrication of high-flux nanofiltration membranes, i.e., thin-film nanofibrous composite (TFNC) nanofiltration membranes. In this work, poly-(l-lactic acid) (PLLA) nanofibrous membranes with adjustable hydrophilicity were successfully fabricated, and then, a PA layer was synthesized on the surface via the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC). The hydrophilicity of PLLA nanofibrous membranes influences the distribution and adsorption weight of PIP, which further affects the formation and morphology of the PA layer. Results indicate that, as the hydrophilicity of PLLA nanofibrous membranes increases, the adsorption amount of PIP increases, the thickness of the PA layer decreases, and the cross-linking degree increases, which ensures both high permeance and high rejection to Na2SO4. The TFNC membranes exhibit a water permeance of 17.0 L·m–2·h–1·bar–1 and a Na2SO4 rejection of 98.0%. This work achieves the control of substrate hydrophilicity by introducing hydrophilic additives and provides new insights for the fabrication of high-performance nanofiltration membranes. [ABSTRACT FROM AUTHOR]

Organic fouling was one of key issues limiting the application of electrodialysis in the treatment of industrial wastewater, which results in degradation of membranes and high energy consumption. In this study, a novel graphene oxide (GO)–polymer modified anion exchange membrane (AEM) for antiorganic fouling was first developed by layer-by-layer interfacial polymerization (IP). The surface of AEM was alternately contacted with GO and tannic acid (TA) aqueous as the water phase and an n-hexane solution of trimesoyl chloride (TMC) as the organic phase; thus, a multilayer GO–polymer structure was fabricated on the surface of AEM. Results showed that the aqueous phase was preferred to be the final treatment of layer-by-layer interfacial polymerization, which was more conducive to enhancing hydrophilicity and negative charge density of the membrane surface. Compared with TA-TMC modified AEM, the introduction of GO nanosheets with carboxyl groups into aqueous solution significantly increased the negative charge density of the membrane surface and reduced membrane resistance. The desalination rate of (GOTA-TMC)1.5 was mostly close to that of pristine AEM without fouling, exhibiting significant antifouling performance and good stability. The study provides promising insights into the modification of ion exchange membranes with functional materials and a polymer composite layer. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have attracted tremendous interest in preparing a thin-film nanocomposite (TFN) membrane. Especially, the membrane performance could be optimized by using MOFs as modifying agents, which takes advantage of their adjustable and regular pore structure, good compatibility with polymers, and superb functional designability. In this study, a tailored TFN polyamide membrane for nanofiltration was successfully fabricated via interfacial polymerization by incorporating MOF-808 into the selective layer on top of a poly-(m-phenylene isophthalamide) (PMIA) substrate. An MOF-808 nanoparticle with a size of approximately 60 nm and a high specific surface area of 1666 m2·g–1 was synthesized using a two-step green method and embedded into the polyamide layer. The surface morphology of the resultant TFN membrane evolved from the nodular structure to a particle aggregation configuration with increased roughness and enhanced hydrophilicity when adding more MOF-808. In particular, the membrane prepared with 0.02 wt % MOF-808 exhibited exceptional water permeance with 17.63 LMH·bar–1 with a well-maintained Na2SO4 rejection of 97.67%, which is superior to commercial membranes and most TFN membranes reported in the literature. The molecular dynamics simulation results showed that the introduction of the MOF-808 filler can significantly enhance the mass transfer of water in the TFN membrane. In addition, the newly designed TFN membrane possessed excellent ion separation performance and superior long-time stability. The findings in this study demonstrate a strategy to regulate the membrane structure, which will provide an impetus for the MOF-based TFN membrane in water treatment and desalination applications. [ABSTRACT FROM AUTHOR]

The development of highly permeable and selective thin-film composite (TFC) membranes is essential for organic solvent nanofiltration (OSN) applications. However, overcoming the permeability–selectivity trade-off in polymer membranes remains highly challenging owing to the difficulty in controlling the thickness and nanostructures of the selective layers. In this study, TFC OSN membranes with sandwich-like structures were developed via interfacial polymerization on Cu-TCPP nanosheet-modified microporous polyvinylidene fluoride (PVDF) substrate surface. The interfacial polymerization was done by using mixed amine (polyethyleneimine and piperazine) in the aqueous phase and the 1,3,5-benzenetricarbonyl trichloride in the hydrophobic ionic liquid phase as monomers. It was found that the Cu-TCPP nanosheets of micrometer lateral dimensions and nanometer thickness (1.5 ± 0.6 nm) can be deposited on the PVDF substrate as an interlayer to facilitate the following interfacial polymerization reaction. The Cu-TCPP interlayer also can be served as a binder between the polyamide selective layer and the microporous PVDF substrate to enhance their mechanical strength. As compared with the PVDF/PA membrane, the PVDF/t-Cu-TCPP/PA membrane exhibited higher elongation (8.0 vs. 4.6%) while ensuring slightly lower tensile strength (36.0 vs. 48.6 MPa). Under optimal synthetic conditions, the TFC membranes could achieve 2.7 L m–2 h–1 bar–1, and 98.9% and 95.0% rejection to Brilliant Blue R (826 Da) and Congo red (697 Da), respectively, in ethanol. Furthermore, the membranes showed steady performance throughout the 36 h nanofiltration of the Rose bengal/ethanol mixture and exhibited good performance in the concentration of lecithin in methanol. Accordingly, this work highlights the potential of using thin metal–organic framework nanosheets as interlayers to develop high-performance TFC membranes for OSN applications. [ABSTRACT FROM AUTHOR]

Machine learning (ML) has been transforming materials science, making great strides in property prediction and materials discovery; however, how ML can bring benefits to nanostructure synthesis, given that the synthesis routines of nanostructures are usually complex with strongly correlated, highly dimensional parameters with narrow experimental window, is rarely explored. Here, we choose hollow nanospheres and emulsion interfacial polymerization as the prototype of material and synthesis routine and propose an ML method to capture synthetic intuitions for guiding the preparation. The quantitative relationship between the reactants, synthesis parameters, and the product morphologies is captured, and the contributions of each feature are analyzed to optimize the reactant amounts and synthesis parameters for hollow and homogeneous spheres. The experimental results are generally consistent with the ML predictions, with the f1-scores of 0.750 and 0.607 for hollow/solid and homogeneity classification, respectively. The obtained hollow carbon spheres show a superior oxygen reduction electrocatalytic performance than solid spheres owing to their improved active site numbers. With the increasing structural complexity of nanomaterials, ML-driven synthetic design will endow great potential and promising prospects. [ABSTRACT FROM AUTHOR]

Nanofiltration membranes (NFMs) with superior permeability and high rejection of both divalent anions and cations are highly desirable to meet the increasing separation demands of complex systems. Herein, we propose a three-in-one strategy to develop a state-of-the-art dually charged thin-film composite (TFC) nanofiltration membrane consisting of a positively charged electrospun nanofiber substrate (NFS) with surface mineralization and a negatively charged polyamide (PA) selective layer prepared by interfacial polymerization (IP). The highly hydrophilic mineralized nanofiber substrate not only effectively reduces the thickness of the PA selective layer but also crumples its structures by the abundant zirconia nanoparticles on the substrate surface, resulting in excellent water flux (15.0 L m -2 h -1 bar -1 ) for the TFC NFMs. The relationship between the thickness of the selective layer and substrate is further investigated using dissipative particle dynamics (DPD) simulations. Meanwhile, the dually charged NFM exhibits relatively high rejection for both anions (97.1% for Na 2 SO 4 and 97.9% for MgSO 4 ) and cations (87.9% for MgCl 2 ) in aqueous solutions compared with single-charged membranes, which is attributed to the dual-repulsion effect of the selective layer and the substrate surface bearing opposite charges. Moreover, the prepared NFMs exhibit good stability and excellent antifouling performance. This work may pave the way for the development of highly efficient nanofiltration membranes for the practical separation of comprehensively charged solutes.

Bubble drainage (BD) occurs in various natural phenomena and industrial activities, in which bubbles rise toward the water surface and create a progressively thinned two-sided liquid film, called a lamella. Surfactant, as an important regulator in the BD process, not only assembles on both sides of the lamellae, generating a configuration of lamellae sandwiched by monolayers of surfactants (lamellae/MS), but also induces interfacial deformation by lowering interfacial tension. Herein, we developed a strategy of BD assisted interfacial polymerization for the fabrication of polyamide (PA) membranes. The regulated interfacial deformation at the water-oil interface produced a membrane with crater-like structures, which greatly increased the surface area of the PA membrane. Moreover, the lamellae/MS configuration served as a reservoir to spontaneously enrich amine monomers and thus modulate the diffusion-reaction kinetics. The resulting PA membranes exhibited superior separation performance with a water permeance of 44.7 L m -2 h -1 bar -1 and a Na 2 SO 4 rejection of 99.2%.

Interlayered thin-film composite (i-TFC) membranes based on 2D materials have been widely studied due to their high efficiency in mass transfer. However, the randomly stacked 2D nanosheets usually increase the fluid path length to some extent. Herein, in situ -grown quasi-vertically oriented 2D ZIF-L was introduced as an interlayer for preparing high-performance reverse osmosis (RO) membranes. Through the optimization of the crystal growth based on the inert polyethylene substrate, the novel i-TFC RO membrane via interfacial polymerization shows an outstanding water permeance (5.50 L m -2 h -1 bar -1 ) and good NaCl rejection (96.3%). The membrane also shows promising potential in domestic water purification and organic solvent separation applications. Compared with the randomly stacked ZIF-L interlayer, the advantages of the vertically oriented one were ascribed to the excellent storage capacity of the amine monomers and the intensified gutter effect. This work will encourage more exploration on the interlayer architectures for high-performance i-TFC membranes.

Finely tuning the pore structure of traditional nanofiltration (NF) membranes is challenging but highly effective for achieving efficient separations. Herein, we propose a concept of using macrocyclic amines (1,4,7-triazacyclononane, 3A; 1,4,7,10-tetraazacyclododecane, 4A1; and 1,4,8,11-tetraazacyclotetradecane, 4A2) with different intra-annular apertures to finely modulate the pore structure of microporous membranes via interfacial polymerization (IP). The boost in the intracavity size of the building blocks results in heightened steric hindrance of these amine monomers, leading to a controlled increase in membrane pore size, as demonstrated by both film characterizations and multiscale simulations. In conjunction with the increased intracavity size, the water permeability follows an augmented trend of 3A-TMC, 4A1-TMC, and 4A2-TMC (TMC: trimesoyl chloride) while exhibiting increased molecular weight cut-offs due to larger free-volume elements and stronger pore interconnectivity. Our proposed macrocyclic amine design strategy provides a guideline for finely regulated microporous membranes with high potential in NF-related applications.

Continuous covalent organic framework (COF) thin membranes have garnered broad concern over the past few years due to their merits of low energy requirements, operational simplicity, ecofriendliness, and high separation efficiency in the application process. This study marks the first instance of fabricating two distinct, self-supporting COF membranes from identical building blocks through solvent modulation. Notably, the precision of the COF membrane's separation capabilities is substantially enhanced by altering the pore alignment from a random to a vertical orientation. Within these confined channels, the membrane with vertically aligned pores and micron-scale stacking thickness demonstrates rapid and selective transportation of Li + ions over Na + and K + ions, achieving Li + /K + and Li + /Na + selectivity ratios of 38.7 and 7.2, respectively. This research not only reveals regulated orientation and layer stacking in COF membranes via strategic solvent selection but also offers a potent approach for developing membranes specialized in Li + ion separation.

Nanofiltration (NF) membranes commonly with a single polyamide (PA) barrier layer play a significant role in the fields of separation and purification. Herein, an NF membrane with double PA layers was successfully fabricated through interfacial polymerization (IP) of a diamine with trimesoyl chloride, and CaCO3 nanoparticles were used as scaffolds. The upper PA layer grounded on the nano-CaCO3 aggregates was incomplete with multidefects. Trimesoyl chloride solution could permeate through the multidefect PA layer to continue IP reaction with diamine underneath the multidefect PA layer to form a bottom defect-free PA layer. The double PA layers almost fitted together, and additional nanovoids were left after removing nano-CaCO3 particles by HCl. The NF membranes with double PA layers exhibited a high water permeance of 34.1 L·m–2·h–1·bar–1, 3.4-fold that of the control sample without sacrificing selectivity. This was attributed to the enhancement of the hydrophilicity and effective filtration area and decrease in PA layer thickness, as well as additional nanovoids to reduce transport resistance. The antifouling performance of the NF membrane was found to be superior to that of the control sample possibly because the upper thin PA layer as a protective layer reduced the contamination to the separation layer. [ABSTRACT FROM AUTHOR]

A cadmium-(II) coordination polymer nanosheet (Cd-nanosheet) has been successfully constructed by a liquid–liquid interface-assisted method based on the coordination reaction between 1,3,5-tri-(4-(2,2':6′,2″-terpyridyl)-phenyl)-benzene and cadmium-(II) nitrate. The Cd-nanosheet was characterized by elemental analysis, FT-IR spectroscopy, XPS, and fluorescence spectroscopy. The expected 2D lamellar structure was also confirmed by various microscopic techniques. The Cd-nanosheet is insoluble in aqueous and organic solvents. Due to its excellent fluorescence performance, we focus on its application in the detection of organic small molecules and metal ions. The luminescence quenching constant Ksv of the Cd-nanosheet for Cu2+ ions and nitrobenzene is 4.73 × 104 and 2.582 × 103 M–1, respectively. The results demonstrate that Cd-nanosheets can serve as detection sensors with high selectivity and sensitivity to detect nitrobenzene and Cu2+ ions. [ABSTRACT FROM AUTHOR]

Interfacial polymerization has emerged as a robust method for fabricating task-specific polyamide (PA) membranes. However, the limited microporosity of highly cross-linked PA membranes constrains their effectiveness in gas separation applications. Herein, we introduce an ionic liquid (IL)-regulated interfacial polymerization process to fabricate polyamide nanofilms incorporating kinked tetrakis (4-aminophenyl) methane monomers. In situ ultraviolet-visible spectroscopy demonstrates that the diffusion of 1,3,5-benzenetricarbonyl trichloride (TMC) toward the interface increases with the IL/H 2 O ratio, leading to the formation of a more compact membrane with a higher cross-linking degree. The PA-TAM7/3-60 min membrane exhibits a CO 2 permeance of 29.8 GPU and a CO 2 /CH 4 selectivity of 109, exceeding the 2008 Robeson upper bond. Additionally, the highly cross-linked structure imparts the membranes with notable plasticization resistance. Mixed-gas tests (CO 2 /CH 4 = 50/50, v/v) reveal that the PA-TAM7/3-60 min membrane experiences only a 2% reduction in CO 2 permeance and a 10% decrease in CO 2 /CH 4 selectivity at a CO 2 partial pressure of 300 PSIG, compared to its performance at 30 PSIG. The ease of tuning membrane structure and gas separation performance, along with its excellent plasticization resistance, underscores the potential of these PA membranes for task-specific gas separations.

Although hydrophilic modification of the membrane surface is widely adopted, polymeric membranes still suffer from irreversible fouling caused by hydrophilic components in surface water. Here, an ultrathin hydrogel layer (40 nm) with hydrophilic-hydrophobic textures was in situ grown onto the polysulfone ultrafiltration membrane surface using an organic-radical-initiated interfacial polymerization technique. The interfacial polymerization of hydrophilic and hydrophobic monomers ensured the molecular-scale distribution of hydrophilic and hydrophobic nanodomains on the membrane surface. These nanodomains, with their molecular lengths, facilitated dynamic repulsion interactions between the uniformly textured surface and foulant components with different degrees of hydrophilicity. Chemical force characterization confirmed that the adhesion force between the hydrophilic-hydrophobic textured membrane surface and foulants (dodecane, bovine serum albumin, and humic acid) was greatly reduced. Dynamic filtration experiments showed that a hydrophilic-hydrophobic textured membrane always possessed the largest water flux and the best antifouling performance. Furthermore, the foulant coverage ratio on the membrane surface was first evaluated by measuring changes in surface streaming potentials, which demonstrated a 69% reduction in the amount of foulant adhering to the hydrophilic-hydrophobic textured membrane surface. Therefore, the construction of hydrophilic-hydrophobic nanodomains on the membrane surface provides a promising strategy for alleviating membrane fouling caused by both hydrophobic and hydrophilic components during ultralow pressurized ultrafiltration processes.

Tissue-inspired layered structural hydrogel has attracted increasing attention in artificial muscle, wound healing, wearable electronics, and soft robots. Despite numerous efforts being devoted to developing various layered hydrogels, the rapid and efficient preparation of layered hydrogels remains challenging. Herein, inspired by the self-growth concept of living organisms, an interfacial catalytic self-growth strategy based on catechol chemistry-mediated self-catalytic system of preparing layered hydrogels is demonstrated. Typically, the tannic acid-metal ion (e.g., TA-Fe 3+ ) complex embedded in the hydrogel substrate would catalytically trigger rapid solid-liquid interfacial polymerization to grow the hydrogel layer without bulk solution polymerization. The self-growth process can be finely controlled by changing the growth time, the molar ratio of Fe 3+ /TA, and so on. The strategy is applicable to prepare various layered hydrogels as well as complex layered hydrogel patterns, allowing the customization of the physicochemical properties of the hydrogel. In addition, the self-adhesive layered hydrogel was prepared and can be utilized as a wearable strain sensor to monitor physiological activities and human motions. The demonstrated interfacial catalytic self-growth strategy will provide a route to design and fabricate layered hydrogel materials.

Organic solvent nanofiltration (OSN) membranes with high separation performance and excellent stability in aggressive organic solvents are urgently desired for chemical separation. Herein, we utilized a polyfunctional arylamine tetra-(4-aminophenyl) ethylene (TAPE) to prepare a highly cross-linked polyamide membrane with a low molecular weight cut-off (MWCO) of 312 Da. Owing to its propeller-like conformation, TAPE formed micropores within the polyamide membrane and provided fast solvent transport channels. Importantly, the rigid conjugated skeleton and high connectivity between micropores effectively prevented the expansion of the polyamide matrix in aggressive organic solvents. The membrane maintained high separation performance even immersed in N , N -dimethylformamide for 90 days. Based on the aggregation-induced emission (AIE) effect of TAPE, the formation of polyamide membrane can be visually monitored by fluorescence imaging technology, which achieved visual guidance for membrane fabrication. This work provides a vital foundation for utilizing polyfunctional monomers in the interfacial polymerization reaction to prepare high-performance OSN membranes.

Polyamide (PA)-based nanofiltration (NF) membranes have demonstrated extensive applications for a sustainable water-energy-environment nexus. A rational control of interfacial polymerization (IP) is highly efficacious to enhance NF separation performance yet remains a technical challenge. Herein, we proposed a regulation strategy of constructing amphiphilic molybdenum disulfide/cetyltrimethylammonium bromide interlayer atop the Kevlar hydrogel substrate. The amphiphilic nanosheet interlayered NF membrane exhibited a crumpled PA surface with an elevated cross-linking degree of 76.9%, leading to an excellent water permeance (16.8 L m -2 h -1 bar -1 ) and an impressive Na 2 SO 4 rejection (99.1%). Meanwhile, the selectivity coefficient of Na 2 SO 4 /NaCl of the optimized TFC membrane reached 91, surpassing those of the recently reported NF membranes. Moreover, the optimized membrane exhibited a desirable rejection of over 90% against Mn 2+ and Cu 2+ in actual textile wastewater. Importantly, the underlying NF membrane formation mechanism was elucidated via both experiments and molecular simulations. The synchronous control of mass and heat transfer of IP process offers a new methodology for the state-of-the-art membrane fabrication, which opens more avenues in softening of brackish water and purification of industrial wastewater containing heavy metal ions.

Carbon nanomembranes (CNMs), with a high density of subnanometer channels, enable superior salt separation performance compared to conventional membranes. However, defects that occur during the synthesis and transfer processes impede their technical realization on a macroscopic scale. Here, we introduce a practical and scalable interfacial polymerization method to effectively heal defects while preserving the subnanometer pores within CNMs. The defect-healed freestanding CNMs show an exceptional performance in forward osmosis (FO), achieving a water flux of 105 L m -2 h -1 and a specific reverse salt flux of 0.1 g L -1 when measured with 1 M NaCl as draw solution. This water flux is 10 times higher than that of commercially available FO membranes, and the reverse salt flux is 70% lower. Through successful implementation of the defect-healing method and support optimization, we demonstrate the synthesis of fully functional, centimeter-scale CNM-based composite membranes showing high water permeance and a high salt rejection. Our defect-healing method presents a promising pathway to overcome limitations in CNM synthesis, advancing their potential for practical salt separation applications.

Covalent organic frameworks have great potential for energy-efficient molecular sieving-based separation. However, it remains challenging to implement COFs as an alternative membrane material due to the lack of a scalable and cost-effective fabrication mechanism. This work depicts a new method for fabricating a scalable in situ COF hollow fiber (HF) membrane by an interfacial polymerization (IP) approach at room temperature. The 2D COF film was constructed on a polyacrylonitrile HF substrate using aldehyde (1,3,5-trimethylphloroglucinol, Tp) and amine (4,4'-azodianiline (Azo) and 4,4',4″-(1,3,5-triazine- 2,4,6-triyl) trianiline (Tta)) as precursors. The COF membrane on the PAN substrate showed 99% rejection of Direct red-80 with remarkable solvent permeance. The rejection analysis revealed that the structural aspects of the solute molecule play a major role in rejection rather than the molecular weight. We further optimized the precursor concentrations to improve the permeation performance of the resulting membrane. The durability study reveals excellent stability of the membrane toward organic solvents. This study also demonstrated the easy scalability of the membrane fabrication approach. The approach was further extrapolated to fabricate a cation-based COF membrane. These charged membranes exhibited an enhanced rejection performance. Finally, this approach can facilitate industrially challenging molecular sieving applications using COF-based membranes.

Crystalline porous metal-organic materials are ideal building blocks for separation membranes because of their molecular-sized pores and highly ordered pore structure. However, creating ultrathin, defect-free crystalline membranes is challenging due to inevitable grain boundaries. Herein, we reported an amorphous metal-organic hybrid (MOH) membrane with controlled microporosity. The synthesis of the MOH membrane entails the use of titanium alkoxide and organic linkers containing di/multicarboxyl groups as monomers in the polymerization reaction. The resultant membranes exhibit similar microporosity to existing molecular sieve materials and high chemical stability against harsh chemical environments owing to the formation of stable Ti-O bonds between metal centers and organic linkers. An interfacial polymerization is developed to fabricate an ultrathin MOH membrane (thickness of the membrane down to 80 nm), which exhibits excellent rejections (>98% for dyes with molecular weights larger than 690 Da) and high water permeance (55 L m -2 h -1 bar -1 ). The membranes also demonstrate good flexibility, which greatly improves the processability of the membrane materials.

Compared to the enormous number of nanostructures that have been documented, the variety of nanostructures produced by organic polymerization is rather limited. We devised an unconventional route and a sustainable approach to distribute tellurium nanoparticles (Te NPs) in a poly(3,4-ethylene dioxythiophene) (PEDOT) matrix to form semiconducting organic-inorganic nanocomposites for potential applications in electrochemical sensing. The adopted strategy of in situ liquid/liquid interface-assisted polymerization aids in the formation of intimately tethered Te NPs on the PEDOT polymer chains, thereby preventing the aggregation of Te NPs. The untapped versatility inherent to using biphasic systems for interfacial polymerization is explored at three interface systems of immiscible solvents: chloroform/water, dichloromethane/water, and hexane/water, giving rise to PEDOT/Te nanocomposite (PTeNC) of distinct morphology. Chemical nature, crystallinity, and morphology investigations proved the successful formation of PTeNC in different interface systems. Consequently, the temporal evolution of interfacial tension in the preferential adsorption of nanoparticles and final product morphology was monitored by pendant drop tensiometry. Owing to the role of morphology, PTeNC synthesized at the hexane/water interface showcased the best electrocatalytic behavior toward nonenzymatic detection of l-ascorbic acid, an essential nutritional factor, and a neuromodulator with a limit of detection of 0.66 μM and excellent sensitivity, selectivity, and reproducibility. Hence, we envision that interface-assisted polymerization offers a nascent and robust strategy for encapsulating unusual electrode materials in polymeric matrices.

Cyclodextrins have been frequently used to fabricate membranes via interfacial polymerization (IP). However, the relatively low reactivity of pristine cyclodextrins often induces a lower cross-linking density and unsatisfactory separation performance. In this work, to introduce a highly active thiolated β-cyclodextrin (CD-SH) monomer into IP progress, we constructed a dense and porous poly(thioester) linkage on a commercial membrane surface with loose nanofiltration by IP of CD-SH and trimesoyl trichloride (TMC) as the monomer in an aqueous phase and organic phase separately for the first time. Furthermore, the reactivity of CD-SH has been fully demonstrated by the two-phase IP aiming at unmodified β-CD, a CD-SH/TMC freestanding membrane with a thicker interfacial layer and a smoother surface, and a PAN/CD-SH membrane with a narrow porous distribution. The composite membrane possessed superior separation performance for a high rejection (83.1-99.6%) of different anionic dyes and a low rejection (<20%) of salts, as well as a high-efficiency sieving ability of dye/dye and dye/salt mixtures. The membrane with a poly(thioester) selective layer could steadily operate in a long-term filtration test and exhibit great stability, chloride-resistance performance, and recyclability.

Thin film composite polyamide (TFC) nanofiltration (NF) membranes represent extensive applications at the water-energy-environment nexus, which motivates unremitting efforts to explore membranes with higher performance. Intrusion of polyamide into substrate pores greatly restricts the overall membrane permeance because of the excessive hydraulic resistance, while the effective inhibition of intrusion remains technically challenging. Herein, we propose a synergetic regulation strategy of pore size and surface chemical composition of the substrate to optimize selective layer structure, achieving the inhibition of polyamide intrusion effective for the membrane separation performance enhancement. Although reducing the pore size of the substrate prevented polyamide intrusion at the intrapore, the membrane permeance was adversely affected due to the exacerbated "funnel effect". Optimizing the polyamide structure via surface chemical modification of the substrate, where reactive amino sites were in situ introduced by the ammonolysis of polyethersulfone substrate, allowed for maximum membrane permeance without reducing the substrate pore size. The optimal membrane exhibited excellent water permeance, ion selectivity, and emerging contaminants removal capability. The accurate optimization of selective layer is anticipated to provide a new avenue for the state-of-the-art membrane fabrication, which opens opportunities for promoting more efficient membrane-based water treatment applications.

Ultraviolet (UV) printing of photopolymers is a widely adopted manufacturing method because of its high resolution and throughput. However, available printable photopolymers are typically thermosets, resulting in challenges in postprocessing and recycling of printed structures. Here, we present a new process called interfacial photopolymerization (IPP) which enables photopolymerization printing of linear chain polymers. In IPP, a polymer film is formed at the interface between two immiscible liquids, one containing a chain-growth monomer and the other containing a photoinitiator. We demonstrate the integration of IPP in a proof-of-concept projection system for printing of polyacrylonitrile (PAN) films and rudimentary multi-layer shapes . IPP shows in-plane and out-of-plane resolutions comparable to conventional photoprinting methods. Cohesive PAN films with number-average molecular weights greater than 15 kg mol -1 are obtained, and to our knowledge this is the first report of photopolymerization printing of PAN. A macrokinetics model of IPP is developed to elucidate the transport and reaction rates involved and evaluate how reaction parameters affect film thickness and print speed. Last, demonstration of IPP in a multilayer scheme suggests its suitabiliy for three-dimensional printing of linear-chain polymers.

Nanofiltration (NF) technology has been widely used in saline wastewater treatment due to its unique separation mechanism. However, the NF membrane, as the core of the nanofiltration technology, is restricted by the trade-off between permeability and selectivity, which greatly restricts the development of NF membranes. The interlamellar arrangement of 2D boron nitride nanosheets (BNNSs) can provide additional transport channels and selectivity, as well as strong adsorption capacity due to its high specific surface area, exhibiting significant potential for advanced membranes. In this work, BNNSs prepared by tannic acid (TA)-assisted exfoliation (TA@BNNSs) were successfully adopted to fabricate thin-film nanocomposite (TFN) membranes via interfacial polymerization (IP). The resultant TFN membranes' structure and properties were systematically characterized via various methods. The results demonstrated that the surface morphology of polyamide membranes evolved gradually from a nodular structure to a reticular topography, accompanied by the decrease of the thickness of the polyamide selective layer when incorporating TA@BNNSs into the membranes. This phenomenon can be mainly ascribed to that the uptake density and diffusion of piperazine (PIP) monomer were effectively regulated by BNNSs. This is validated by molecular dynamics and revealed by the adsorption of PIP in BN models, the diffusion coefficients, and interaction energies, respectively. In addition, the TFN membranes demonstrated improved permeance and stable solute rejection for the inorganic salts. Specifically, the water flux of PA-TA@BNNSs-10%/PMIA membrane could reach up to 109.1 ± 2.49 L·m -2 ·h -1 while keeping a high rejection of 97.5 ± 0.38% to Na 2 SO 4 , which was superior to most of the reported membranes in the literature. Besides, the PA-TA@BNNSs-10%/PMIA membrane exhibited an excellent stability in the long-term filtration process. The finding in this work provides a potential strategy for developing the next-generation 2D material-based membranes with high-performance for separation applications.

Interfacial polymerization (IP) provides a versatile platform for fabricating defect-free functional nanofilms for various applications, including molecular separation, energy, electronics, and biomedical materials. Unfortunately, coupled with complex natural instability phenomena, the IP mechanism and key parameters underlying the structural evolution of nanofilms, especially in the presence of surfactants as an interface regulator, remain puzzling. Here, we interfacially assembled polymer nanofilm membranes at the free water-oil interface in the presence of differently charged surfactants and comprehensively characterized their structure and properties. Combined with computational simulations, an in situ visualization of interfacial film formation discovered the critical role of Marangoni instability induced by the surfactants via various mechanisms in structurally regulating the nanofilms. Despite their different instability-triggering mechanisms, the delicate control of the surfactants enabled the fabrication of defect-free, ultra-permselective nanofilm membranes. Our study identifies critical IP parameters that allow us to rationally design nanofilms, coatings, and membranes for target applications.

The foliar loss of pesticides causes serious utilization decline and environmental risk. On the basis of biomimetics, pesticide-loaded microcapsules (MCs) with spontaneous deformation on foliar micro/nanostructures, like the snail suction cup, are prepared by interfacial polymerization. By controlling the usage or types of small alcohols in the MC preparation system, the flexibility of MCs is tunable. Through the investigation of emulsions and MC structures, we discover that the migration and distribution of small alcohols driven by amphiphilicity affect the process of interfacial polymerization between polyethylene glycol and 4,4-methylenediphenyl diisocyanate. By hydrophobic modification of the polymer and competition for oil monomers of small alcohols, the thickness and compactness of shells are reduced, whereas the density of the core is increased. As a result of the regulation in structures, the flexibility of MCs is improved significantly. In particularly, the MCs-N-pentanol (0.1 mol kg -1 ) with the best flexibility show strong scouring resistance on varied foliar structures, sustained release property on the air/solid interface, and persistent control effect against foliar diseases. The pesticide-loaded soft MCs provide an effective way to improve pesticide foliar utilization.

Nanofiltration (NF) is an effective technology for removing trace organic contaminants (TrOCs), while the inherent trade-off effect between water permeance and solute rejections hinders its widespread application in water treatment. Herein, we propose a novel scheme of "monomers with sacrificial groups" to regulate the microstructure of the polyamide active layer via introducing a hydrolyzable ester group onto piperazine to control the diffusion and interfacial polymerization process. The achieved benefits include narrowing the pore size, improving the interpore connectivity, enhancing the microporosity, and reducing the active layer thickness, which collectively realized the simultaneous improvement of water permeance and enhancement of TrOCs rejection performance. The resulting membranes were superior to both the control and commercial membranes, especially in water-TrOCs selectivity. The effects of using the new monomers on the membrane physicochemical properties were systematically studied, and underlying mechanisms for the enhanced separation performance were further revealed by simulating the polymerization process through density functional theory calculation and measuring the trans-interface diffusion rate of monomers. This study demonstrates a novel promising NF membrane synthesis strategy by designing the structure of reaction monomers for achieving excellent rejection of TrOCs with a low energy input in water treatment.

Tuning the crosslinking density of interfacial-polymerized nanofiltration (NF) membranes varying from loose to dense structures can make them meet the demand of various applications. The properties (e.g., pore size and porosity) of NF membranes can be tuned by choosing monomers with different structures and reactivities. Herein, tris(hydroxymethyl)aminomethane (THAM), a low-cost and green monomer, is first employed for the preparation of poly(ester amide) (PEA) thin-film composite membranes via interfacial polymerization. The moderate reactivity of THAM enables rational regulation of the crosslinking density of PEA membranes from loose to dense structures by varying the THAM concentration, which can hardly be achieved for traditional polyamide or polyester membranes. The developed PEA membranes with a wide tunability range of crosslinking densities broaden their potential utility in NF. PEA membranes with dense structures show exceptional desalination performance with a water permeance of 11.1 L m -2 h -1 bar -1 and a Na 2 SO 4 rejection of 97.1%. However, loose PEA membranes exhibit good dye/salt separation performance with a dye removal rate over 95.0% and negligible NaCl rejection (<7.5%), as well as high water permeance (>45 L m -2 h -1 bar -1 ). This work implies that PEA membranes with tunable crosslinked structures provide new possibilities for the development of task-specific separation membranes.

Molecularly organized nanocomposites of polymers and carbon nanotubes (CNTs) have great promise as high-performance materials; in particular, conformal deposition of polymers can control interfacial properties for mechanical load transfer, electrical or thermal transport, or electro/chemical transduction. However, controllability of polymer-CNT interaction remains a challenge with common processing methods that combine CNTs and polymers in melt or in solution, often leading to nonuniform polymer distribution and CNT aggregation. Here, we demonstrate CNTs within net-shape sheets can be controllably coated with a conformal coating of meta-aramid by simultaneous capillary infiltration and interfacial polymerization. We determine that π-interaction between the polymer and CNTs results in chain alignment parallel to the CNT outer wall. Subsequent nucleation and growth of the precipitated aramid forms a smooth continuous layered sheath around the CNTs. These findings motivate future investigation of mechanical properties of the resulting composites, and adaptation of the in situ polymerization method to other substrates.

In spite of extensive research, fouling is still the main challenge for nanofiltration membranes, generating an extra transport resistance and requiring a larger operational pressure in practical applications. We fabricated a highly antifouling nanofiltration membrane by grafting poly( N -isopropylacrylamide) (PNIPAM) chains on a bromine-containing polyamide layer. The resulting membrane was found to have a double permeance compared to the pristine membrane, while the rejection of multivalent ions remained the same. In addition, PNIPAM chains yielded a better deposition resistance and adhesion resistance, thereby mitigating the increase of fouling and promoting the recovery of flux during the filtration and traditional cleaning stages, respectively. Moreover, PNIPAM chains shrank when the water temperature was above the lower critical solution temperature (LCST), indicating the formation of a buffer layer between the membrane and pollutants. The buffer layer would eliminate the membrane-foulant interaction energy, thus further enhancing the detachment of pollutants. This simple and efficient cleaning method could act as an enhanced cleaning procedure to remove irreversible fouling. This provides new insights into the fabrication of enhanced antifouling membranes using smart responsive polymer chains.

Covalent organic frameworks (COFs) have evinced a potential solution that promises for fast and efficient molecular separation due to the presence of orderly arranged pores and regulable pore apertures. Herein, the synthesized COF (TPB-DMTP-COF) with the pore aperture matching the pore size of the nanofiltration (NF) membrane was utilized to modulate the physicochemical characters of the polyamide (PA) membranes. It is demonstrated that COFs with superior polymer affinity and hydrophilicity not only circumvent the nonselective interfacial cavities but also improve the hydrophilicity of the resultant thin-film nanocomposite (TFN) membranes. Furthermore, the predeposited COF layer is able to slow down the diffusion rate toward the reaction boundary through hydrogen bonding, which is consistent with the results of molecular dynamic (MD) and dissipative particle dynamic (DPD) simulations. In this context, COF-modulated TFN membranes show a roughened and thickened surface with bubble-shaped structures in contrast to the nodular structure of original polyamide membranes. Combined with the introduced in-plane pores of COFs, the resultant TFN membranes display a significantly elevated water permeance of 35.7 L m 2 h -1 bar -1 , almost 4-fold that of unmodified polyamide membranes. Furthermore, the selectivity coefficient of Cl - /SO 4 2- for COF-modulated TFN membranes achieves a high value of 84 mainly related to the enhanced charge density, far exceeding the traditional NF membranes. This work is considered to provide a guideline of exploring hydrophilic COFs as an interlayer for constructing highly permeable membranes with precise ion-sieving ability.

Transition-metal carbides (MXenes), multifunctional 2D materials, have caught the interest of researchers in the fabrication of high-performance nanocomposite membranes. However, several issues regarding MXenes still remain unresolved, including low ambient stability; facile restacking and agglomeration; and poor compatibility and processability. To address the aforementioned challenges, we proposed a facile, green, and cost-efficient approach for coating a stable layer of plant-derived polyphenol tannic acid (TA) on the surface of MXene (Ti 3 C 2 T x ) nanosheets. Then, high-performance reverse osmosis polyamide thin film nanocomposite (RO-PA-TFN) membranes were fabricated by the incorporation of modified MXene (Ti 3 C 2 T x -TA) nanosheets in the polyamide selective layer through interfacial polymerization. The strong negative charge and hydrophilic multifunctional properties of TA not only boosted the chemical compatibility between Ti 3 C 2 T x MXene nanosheets and the polyamide matrix to overcome the formation of nonselective voids but also generated a tight network with selective interfacial pathways for efficient monovalent salt rejection and water permeation. In comparison to the neat thin film composite membrane, the optimum TFN (Ti 3 C 2 T x -TA) membrane with a loading of 0.008 wt % nanofiller revealed a 1.4-fold enhancement in water permeability, a well-maintained high NaCl rejection rate of 96% in a dead-end process, and enhanced anti-fouling tendency. This research offers a facile way for the development of modified MXene nanosheets to be successfully integrated into the polyamide-selective layer to improve the performance and fouling resistance of TFN membranes.

Effective control of monomer diffusion and reaction rate is the key to achieving a controlled interfacial polymerization (IP) and a high-performance nanofiltration (NF) membrane. Herein, an integration of multirole regulations was synchronously realized using poly(acrylic acid) (PAA) as an active additive in a piperazine (PIP) aqueous phase. Thanks to synergistic interactions, including hydrogen bonding, electrostatic interaction, and covalent bonding between PAA and PIP molecules, together with the increased viscosity of the solution, PIP diffusion was rationally controlled. Moreover, interfacial polycondensation was also restrained via the modestly reduced pH of the aqueous solution. These contribute to the formation of a thinner, looser, more hydrophilic, and higher negatively charged PAA-decorated polyamide selective layer with a unique nanostrand-nodule morphology. The harvested NF-PAA/PIP membrane showed an ∼70% rise in water permeability (up to 23.5 L·m -2 ·h -1 ·bar -1 ) while retaining high Na 2 SO 4 and dye rejections. Furthermore, the optimized NF-PAA/PIP membrane presented a superior fouling resistance capability for typical pollutants, as well as long-term stability during successive filtration. Thus, this work offers a straightforward and impactful approach to regulating IP and promoting NF membrane properties.

The metal-organic framework (MOF)-based polyamide (PA) membranes applied for desalination with high permeability and selectivity are attracting more and more attention. However, the design and fabrication of high-quality and stable MOF-based PA nanocomposite reverse osmosis (RO) membrane still remain a big challenge. Herein, Fe 3+ -polyphenolic complex coating via interfacial coordination was first explored as an interlayer of an in situ assembled stable and high-quality Fe(BTC)-based PA nanocomposite RO membranes for desalination. Although depositing the Fe 3+ -polyphenolic complex on the polymer support, sufficient heterogeneous nucleation sites for the in situ synthesizing Fe(BTC) are provided. Using this strategy, we can not only facilely prepare continuous MOF-based PA nanocomposite RO membranes, ignoring the complicated and time-consuming co-blending process and the MOF-particle aggregation, but also restrict the formation of PA matrix inside the pores of the support membrane and increase the rigidity of the polyamide chain. The method also gives a proper level of generality for the fabrication of versatile stable MOF-based PA RO membranes on various supports. The prepared PA/Fe(BTC) composite membrane exhibited excellent separation performance with a large permeate flux of 2.93 L m -2 h -1 bar -1 and a high NaCl rejection of 96.8%.

Pharmaceutical, chemical, and food industries are actively implementing membrane nanofiltration modules in their processes to separate valuable products and recover solvents. Interfacial polymerization (IP) is the most widely used method to produce thin-film composite membranes for nanofiltration and reverse osmosis processes. Although membrane processes are considered green and environmentally friendly, membrane fabrication has still to be further developed in such direction. For instance, the emission of volatile solvents during membrane production in the industry has to be carefully controlled for health reasons. Greener solvents are being proposed for phase-separation membrane manufacture. For the IP organic phase, the proposition of greener alternatives is in an early stage. In this work, we demonstrate the preparation of a high-performing composite membrane employing zero vapor pressure and naturally extracted oleic acid as the IP organic phase. Its long hydrophobic chain ensures intrinsic low volatility and acid monomer dissolution, while the polar head induces a unique self-assembly structure during the film formation. Membranes prepared by this technique were selective for small molecules with a molecular weight cutoff of 650 g mol -1 and a high permeance of ∼57 L m -2 h -1 bar -1 .

Thin-film composite (TFC) membranes are attracting wide attention because their ultrathin selective layer usually corresponds to the higher membrane flux for pervaporation. However, the direct preparation of the TFC membranes on ceramic substrates confronted with the great difficulties because the larger pores on ceramic substrate surfaces are detrimental to the formation of an intact polyamide (PA) selective layer produced by interfacial polymerization (IP) reaction. Here, the integrated ZIF-L nanosheets were proposed to be used as an assistance interlayer for the first time to eliminate the existence of the pores of the ceramic support, and provides a better basis for the formation of an intact PA selective layer by IP reaction between TMC and ethylenediamine (EDA). The experimental data obtained in pervaporation (PV) show that the increased flux from 1.1 to 2.9 kg/m 2 h corresponds to the decreased separation factor from 396 to 110 when the feed concentration of ethanol decreases from 95 wt % to 80 wt % at 50 °C. In addition, the membrane flux increases from 0.8 to 2.5 kg/m 2 h with a change of the separation factor from 683 to 111 when the operational temperature varies from 30 to 60 °C. These results demonstrate the great potential of the fabricated TFC membranes in practical application for PV dehydration of organic solutions.

Covalent organic frameworks are potential candidates for the preparation of advanced molecular separation membranes due to their porous structure, uniform aperture, and chemical stability. However, the fabrication of continuous COF membranes in a facile and mild manner remains a challenge. Herein, a continuous, defect-free, and flexible azine-linked ACOF-1 membrane was prepared on a hydrolyzed polyacrylonitrile (HPAN) substrate via in situ interfacial polymerization (IP). A moderately crystalline COF ultrathin selective layer enabled ultrafast molecular sieving. The effect of synthesis parameters including precursor concentration, catalyst dosage, and reaction duration on the dye separation performance was investigated. The optimized membrane displayed an ultrahigh water permeance of 142 L m -2 h -1 bar -1 together with favorable rejection (e.g., 99.2% for Congo red and 96.3% for methyl blue). The water permeance is 5-12 times higher than that of reported membranes with similar rejections. In addition, ACOF-1 membranes demonstrate outstanding long-term stability together with organic solvent and extreme pH resistance. Meanwhile, the membrane is suitable for removing dyes from salt solution products owing to their nonselective permeation for hydrated salt ions (<10.6%). The superior performance and the excellent chemical stability render the ACOF-1 membrane a satisfactory system for water purification.

A highly permselective nanofiltration membrane was engineered via zwitterionic copolymer assembly regulated interfacial polymerization (IP). The copolymer was molecularly synthesized using single-step free-radical polymerization between 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride (AEMA) (P[MPC- co -AEMA]). The dynamic network of P[MPC- co -AEMA] served as a regulator to precisely control the kinetics of the reaction by decelerating the transport of piperazine toward the water/hexane interface, forming a polyamide (PA) membrane with ultralow thickness of 70 nm, compared to that of the pristine PA (230 nm). Concomitantly, manipulating the phosphate moieties of P[MPC- co -AEMA] integrated into the PA matrix enabled the formation of ridge-shaped nanofilms with loose internal architecture exhibiting enhanced inner-pore interconnectivity. The resultant P[MPC- co -AEMA]-incorporated PA membrane exhibited a high water permeance of 15.7 L·m -2 ·h -1 ·bar -1 (more than 3-fold higher than that of the pristine PA [4.4 L·m -2 ·h -1 ·bar -1 ]), high divalent salt rejection of 98.3%, and competitive mono-/divalent ion selectivity of 52.9 among the state-of-the-art desalination membranes.

Metal-organic framework (MOF) materials have received extensive attention for the design of advanced thin-film nanocomposite (TFN) membranes with excellent permselectivity. However, the relationship between the unique physicochemical properties and performance of engineered MOF-based membranes has yet to be extensively investigated. In this work, we investigate the incorporation of porous zinc-based MOFs (Zn-MOFs) into a polyamide active layer for the fabrication of TFN membranes on porous poly(phenylsulfone) (PPSU) support layers through an interfacial polymerization approach. The actual effects of varying the amount of Zn-MOF added as a nanofiller on the physicochemical properties and desalination performance of TFN membranes are studied. The presence and layout of Zn-MOFs on the top layer of the membranes were confirmed by X-ray photoelectron spectroscopy, scanning electron microscopy, and ζ potential analysis. The characterization results revealed that Zn-MOFs strongly bind with polyamide and significantly change the membrane chemistry and morphology. The results indicate that all four studied TFN membranes with incorporated Zn-MOFs enhanced the water permeability while retaining high salt rejection compared to a thin-film composite membrane. Moreover, the highest-performing membrane (50 mg/L Zn-MOF added nanofiller) not only exhibited a water permeability of 2.46 ± 0.12 LMH/bar but also maintained selectivity to reject NaCl (>90%) and Na 2 SO 4 (>95%), similar to benchmark values. Furthermore, the membranes showed outstanding water stability throughout 72 h filtration and chlorine resistance after a 264 h chlorine-soaking test because of the better compatibility between the polyamide and Zn-MOF nanofiller. Therefore, the developed TFN membrane has potential to solve trade-off difficulties between permeability and selectivity. Our findings indicate that porous Zn-MOFs play a significant role in the development of a TFN membrane with high desalination performance and chlorine resistance.