Multilayer Composite Membranes Research Articles

Asymmetric multilayered cellulose nanofiber composite membranes with electrical-magnetic dual-gradient architectures towards excellent electromagnetic interference shielding performance

The structural design strategies of MXene-based nanocomposites have demonstrated critical significance for electromagnetic interference (EMI) shielding applications. Herein, novel asymmetric multilayered cellulose nanofiber/multiwalled carbon nanotube@ferroferric oxide/MXene (CNF/MWCNT@Fe3O4/MXene) composite membranes with electrical-magnetic dual-gradient structures were prepared via layered-by-layered self-assembly strategy. Briefly, CNF/MWCNT@Fe3O4 layers are designed as the negative gradient absorption layers which provide dielectric/magnetic double loss. Meanwhile, MXene layers serve as the positive gradient reflection layers which generate multiple reflections and conduct loss. Thus, gradient multilayered CNF/MWCNT@Fe3O4/MXene composite membranes exhibit a total electromagnetic interference shielding effectiveness (EMI SET) of 73.20 dB at the thickness of 180 μm and R-value of 0.99934 in the X-band. Furthermore, the asymmetric gradient multilayer composite membrane reveals a superior EMI shielding performance in comparison with that of homogeneous multilayered composite membranes. When electromagnetic waves (EMWs) pass through the gradient multilayered CNF/MWCNT@Fe3O4/MXene composite membrane, the rational asymmetric gradient multilayered structures contribute to a “gradually decreasing absorption-gradually increasing reflection” shielding mechanism. Thereby, the design strategy of asymmetric electrical-magnetic dual-gradient structures is advantageous in enhancing the EMI shielding ability of polymeric composites.

Eco-Friendly Superhydrophobic Modification of Low-Cost Multi-Layer Composite Mullite Base Tubular Ceramic Membrane for Water Desalination

This study aimed to investigate and develop a cost-effective and superhydrophobic ceramic membrane for direct contact membrane distillation (DCMD) applications. Two types of mullite-based composite membranes were prepared via extrusion and sintering techniques. To create a small and narrow pore diameter distribution on the membrane surface, the dip-coating technique with 1 µm alumina was employed. The hexadecyltrimethoxysilane eco-friendly grafting agent was adopted to modify low-cost multilayer mullite-based composite membranes, transforming them from hydrophilic to superhydrophobic. The prepared membranes were characterized via field emission scanning electron microscopy (FESEM), energy-dispersive spectrometry (EDS), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), liquid entire pressure (LEP), contact angle, atomic force microscopy (AFM), porosity, and membrane permeability. The results of the prepared membranes validate the appropriateness of the material for membrane distillation applications. The optimized membrane, with a contact angle of 160° and LEP = 1.5 bar, was tested under DCMD using a 3.5 wt.% sodium chloride (NaCl) synthetic solution and Persian Gulf seawater as a feed. Based on the acquired results, an average permeate flux of 3.15 kg/(m2·h) and salt rejection (R%) of 99.62% were found for the 3.5 wt.% NaCl solution. Moreover, seawater desalination showed an average permeate flux of 2.37 kg/(m2·h) and salt rejection of 99.81% for a 20-h test without any pore wetting. Membrane distillation with a hydrophobic membrane decreased the turbidity of seawater by 93.13%.

Preparation of stable multilayer PDMS composite pervaporation membrane incorporated with in-situ transformed metal organic frameworks for enhanced butanol recovery

In this study, stable and non-defective multilayer polydimethylsiloxane (PDMS) composite pervaporation mixed matrix membranes incorporated with in-situ transformed metal organic frameworks was successfully synthesized via ligand vapor phase infiltration and spin-coating. Metal zinc sources were uniformly distributed in PDMS which were in-situ transformed into homogeneous zeolitic imidazolate framework-8 (ZIF-8) nanoparticles, effectively alleviating the aggregation of ZIF-8. Thermal cross-linking of PDMS and the formation of MOFs occurred simultaneously, omitting the complicated preparation and re-dispersion steps of MOF nanoparticles. MOF nanoparticles and PDMS formed a more stabilized composite structure by in-situ transformation, in which PDMS and metal of MOFs can interact with the -Si-O- of silane coupling groups on membrane surface to construct solid multilayer composite membrane, ensuring long-term stability. Moreover, with the aid of hydrophobic interlayer, polymer infiltration into channels of substrate was restricted and casting solution spread out smoothly, facilitating the formation of defect-free PDMS selective layer. Various techniques including Attenuated Total Reflection-Fourier Transform Infrared Spectrometer, Field Emission Scanning Electron Microscopy, Atomic Force Microscope and X-ray Diffraction were applied to explore the morphology, composition and structure of nanoparticles and membranes, and pervaporation tests were taken to investigate the behavior of hydrophobic polymer-based multilayer membranes. For the recovery of low concentration n-butanol, the prepared non-defective multilayer TAO/ZIF-8/K-PDMS composite membrane displayed excellently total permeate flux of 2890 g m−2 h−1 with competitive separation factor of 40.3.

Layer-by-layer self-assembly method improves the performance and cytocompatibility of 3D printing ODMA-GelMA hydrogel

The GelMA hydrogels are biomaterials with excellent biocompatibility and cellular activity. However, their application is limited due to their poor mechanical properties. To enhance the mechanical properties of GelMA, we incorporated ODMA into GelMA for the sequential assembly of RSF (raw silk fiber protein) and CHI (chitosan) through electrostatic interactions, constructing a multi-layer composite membrane on the hydrogel surface. We conducted microscopic morphology analysis, evaluated mechanical properties, assessed cytocompatibility, and performed short-term and long-term material toxicity testing. Our results showed that mechanical properties were significantly enhanced when the 10-layer (RSF/CHI) composite film was assembled on the surface of ODMA-GelMA hydrogel. And they also exhibited excellent cytocompatibility. The improved GelMA hydrogel has the potential for biomedical applications in 3D printing as a substitute for artificial organs.

Robust alternating multilayered cellulose nanofiber composite membranes fabricated by high-efficiency calcium ion-precomplexed vacuum-assisted self-assembly towards electromagnetic interference shielding

Robust alternating multilayered cellulose nanofiber composite membranes fabricated by high-efficiency calcium ion-precomplexed vacuum-assisted self-assembly towards electromagnetic interference shielding

Multilayer composite membranes composed of carbon molecular sieve membranes sandwiched between stacked zeolite nanosheets

This study proposes a novel method for fabricating composite membranes with a unique multilayer structure comprising Mobil-type five (MFI) zeolite nanosheets and carbon molecular sieve (CMS) membranes. The proposed fabrication method involves direct solution casting of a nanosheet/polymer composite onto porous alumina supports and subsequent carbonization, thereby eliminating the necessity for intermediate layers, typically required in most conventional supported CMS membranes. The fabricated membranes exhibit clear molecular sieving separation attributes, demonstrating the efficiency of the proposed method in preparing membranes without intermediate layers. Furthermore, the membranes exhibit an intriguing morphological configuration, wherein the CMS layers occupy the interstitial spaces between the stacked zeolite nanosheets. Therefore, compared with conventional CMS membranes without nanosheets, the fabricated CMS membrane with MFI nanosheets contain a significant proportion of sp2 bonded carbon atoms. The distinct physical and chemical structures of the composite membrane considerably improve its stability against structural densification associated with physical aging. A marginal H2 permeance reduction is observed for the 6 and 10 wt% loading samples of the composite membrane after aging for 100 d at 180 °C. Moreover, the H2/CO2 selectivity of the 6 wt% loading sample of the aged membrane increased from approximately 4 to 21, surpassing the upper bound of the corresponding gas pair. Thus, the proposed method can be used for fabricating molecular sieve membranes owing to its advantages such as ease of membrane preparation and gas-separation performance and structural stability enhancements of the fabricated membranes.

Emerging Strategies for the Biofabrication of Multilayer Composite Amniotic Membranes for Biomedical Applications.

The amniotic membrane (AM) is the innermost part of the fetal placenta, which surrounds and protects the fetus. Due to its structural components (stem cells, growth factors, and proteins), AMs display unique biological properties and are a widely available and cost-effective tissue. As a result, AMs have been used for a century as a natural biocompatible dressing for healing corneal and skin wounds. To further increase its properties and expand its applications, advanced hybrid materials based on AMs have recently been developed. One existing approach is to combine the AM with a secondary material to create composite membranes. This review highlights the increasing development of new multilayer composite-based AMs in recent years and focuses on the benefits of additive manufacturing technologies and electrospinning, the most commonly used strategy, in expanding their use for tissue engineering and clinical applications. The use of AMs and multilayer composite-based AMs in the context of nerve regeneration is particularly emphasized and other tissue engineering applications are also discussed. This review highlights that these electrospun multilayered composite membranes were mainly created using decellularized or de-epithelialized AMs, with both synthetic and natural polymers used as secondary materials. Finally, some suggestions are provided to further enhance the biological and mechanical properties of these composite membranes.

Construction of a multi-layer protection of CS polymer brush grafted DA@CNTs coating on PVDF membrane for effective removal of dye effluent

In the process of removing dye wastewater, the membrane surface is susceptible to contamination, resulting in reduced performance and limited dye separation efficiency. A single hydrophilic modification layer is not enough to achieve effective separation of different types of dyes. The present research designed a "double layer protection" method in order to overcome the above deficiencies. A solution of dopamine (DA) coated carbon nanotubes (CNTs-COOH) was covered on the surface of the polyvinylidene fluoride (PVDF) membrane by deposition, followed by grafting a layer of chitosan (CS) polymer brushes on its surface. The spatial double layer structure provides an excellent barrier effect and effectively reduces the contamination of dyes. When filtering different types of dyes, effective filtration of anionic and cationic dyes through the electrostatic effect of the first layer, the adsorption of CNTs in the second layer and the hydration layer of both layers. All membranes have excellent rejection properties. More importantly, the membranes also had good chemical and mechanical stability and their serviceability was not degraded. Therefore, the prepared PVDF-based multi-layer composite membranes behave a potential application prospect in the wastewater purification field.

Design of PTFE/PP multilayer composite membrane as mask filter layer with steady filtration efficiency and high dust holding capacity

Currently, commercially available mask filter materials, such as electrostatic electret polypropylene (PP) melt-blown cloth and polytetrafluoroethylene (PTFE) nanofiber membranes, always suffer a compromise between filtration efficiency and dust holding capacity, when used alone during air purification. In this study, a novel multilayer composite membrane was designed by thermally laminating a PP melt-blown filter layer (as the dust-holding layer) and a PTFE (Polytetrafluoroethylene) nanofiber layer (as the filtration layer), to improve filtration stability and capacity. The performance of the composite membrane was examined in relation to the effect of key laminating parameters (i.e., temperature, pressure and speed) on the dust holding capacity, filtration efficiency and resistance. NaCl aerosol was used as the model dust source. Results show that the composite membrane, prepared at a lamination temperature of 120 °C, a lamination pressure of 0.2 MPa and a lamination speed of 4 m/min, had a dust-holding capacity of 12.21 g/m2, which was over six times higher than that of the PTFE nanofiber membrane alone. During ten repeated cycles of NaCl aerosol filtration, water washing and alcohol disinfection, the composite membrane exhibited a steady filtration efficiency of above 99.9% over the NaCl aerosol. Meanwhile, the dust holding capacity was maintained above 8 g/m2 over the multiple cycles, while the resistance was smaller than 70 Pa.

Nanofibrous polycaprolactone/amniotic membrane facilitates peripheral nerve regeneration by promoting macrophage polarization and regulating inflammatory microenvironment.

Appropriate levels of inflammation are an important part of functional repair of nerve damage. However, excessive inflammation can cause the continuous activation of immune inflammatory cells and degeneration of nerve cells. Regulating the temporal and spatial changes in M1/M2 macrophages can regulate the local inflammatory immune environment of the tissue to promote its transformation to a direction conducive to tissue repair.In the present study, a multi-layer multifunctional nanofiber composite membrane of polycaprolactone(PCL) and amniotic membrane (AM) was constructed using electrospinning. In vitro studies have shown that the PCL/AM composite promoted the axon growth of SH-SY5Y cells and induced their differentiation into neurons. The PCL/AM composite wrapped the nerve stump to form a microenvironment that was conducive to nerve regeneration, blocked the invasion of scar tissue, promoted the recruitment of macrophages and moderate polarization to M2, enhanced the expression of anti-inflammatory factors IL-10 and IL-13, inhibited the expression of pro-inflammatory factors IL-6 and TNF-α, and induced myelin sheath and axon regeneration. By releasing various bioactive substances to regulate the polarization of M2 macrophages and formation of anti-inflammatory factors, the PCL/AM composite can enhance axonal regeneration and improve nerve repair.

Design and optimization of multilayer composite membrane for biomethane enrichment: Process simulations and economics

The depletion of fossil fuels has led to the development of various biogas upgrading techniques that can be a reliable and sustainable energy source. At present, membrane-based gas separation and enrichment have received more acceptance to contend with the traditional biogas upgrading processes. Remarkably, multilayered composite membranes (MCM) fabricated from selective polymers and fillers have achieved high consideration in the field of CO2separation. In this regard, the present study focuses on fabricating and optimizing the porous layer of MCM using Polyether sulfone (PES) and Torlon polymers and their morphological influences on overall membrane performance. The MCM membranes fabricated from the PES porous substrate exhibited 3–4 fold higher permeation than the Torlon. Besides, the effect of zeolite type and % loading on the selective layer performance in CO2gas permeation was examined. From the gas permeation experiments, a 6 % loaded 3A zeolite sample exhibited maximum permeation flux for CO2, which is 1.7 folds compared to the neat Polyether block amide (PEBAX)/PES membrane and 5.8 fold to the neat PEBAX/Torlon without compromising the selectivity. Furthermore, process simulation using Aspen Hysys reveals the economic feasibility of membrane-based biomethane enrichment. Overall, the study results are compared with Robeson’s plot, which reveal the substantial potential of MCM-based membrane technology as a biogas upgrading process and offers assistance in developing an appropriate porous support for MCM.

Polymeric high-molecular compounds as a basis for creating composite multilayer membranes

The problem of preparation of drinking water is considered, which includes the study of the system "diluted aqueous solution - membrane - corrected diluted aqueous solution", where the membrane, as the main element and external factor of baromembrane processes, must meet certain physicochemical parameters and requirements. It is shown that for the effective use of baromembrane processes in solving the problem of adjusting the composition of diluted aqueous solutions, it is necessary to create a series of membranes with selective selectivity based on the principle of synthesis and creation of the polymer and its structural factors. The methodology for the synthesis of a high-molecular polymer, which by adjusting the ratio of the components of its composition and the conditions for obtaining new proper structures, determines such parameters as hydrophilicity, selectivity and permeability, along with the main chemical and physicochemical properties. A number of polymer materials that differ in chemical and thermal resistance have been determined, as well as new approaches to creating a thin barrier layer for both asymmetric and composite membranes. Micrographs of the structure of microfiltration polysulfone membranes are presented. The results of experimental studies of the obtained samples of multilayer composite membranes are given. The curves of the dependence of the selectivity of multilayer polymer membranes on such operating parameters of the reverse osmosis process as time and operating pressure are shown.

Thin-Film Composite Matrimid-Based Hollow Fiber Membranes for Oxygen/Nitrogen Separation by Gas Permeation.

In recent years, the need to reduce energy consumption worldwide to move towards sustainable development has led many of the conventional technologies used in the industry to evolve or to be replaced by new alternatives. Oxygen is a compound with diverse industrial and medical applications. For this reason, obtaining it from air is one of the most interesting separations, traditionally performed by cryogenic distillation and pressure swing adsorption, two techniques which are very energetically expensive. In this sense, the implementation of membranes in a hollow fiber configuration is presented as a much more efficient alternative to carry out this separation. The aim of this work is to develop cost-effective multilayer hollow fiber composite membranes made of Matrimid and polydimethylsiloxane (PDMS) for the separation of oxygen and nitrogen from air. PDMS is used as a cover layer but can also enhance the performance of the membrane. In order to compare these two materials, three different configurations are studied. First, integral asymmetric Matrimid hollow fiber membranes were produced using the spinning method. Secondly, by using dip-coating method, a PDMS dense selective layer was deposited on a self-made polyvinylidene fluoride (PVDF) hollow fiber support. Finally, the performance of a dual-layer hollow fiber membrane of Matrimid and PDMS was studied. Membrane morphology was characterized by SEM and separation performance of the membranes was evaluated by mixed-gas permeation experiments. The novelty presented in this work is the manufacture of hollow fiber membranes and the way Matrimid is treated. This makes it possible to develop much thinner dense layers than in the case of flat-sheet membranes, which leads to higher permeance values. This is a key factor when implementing this technology on an industrial scale. Membranes prepared in this work were compared to the current state of the art, reporting quite good performance for the dual-layer membrane, reaching O2 permeance of 30.8 GPU and O2/N2 selectivity of 4.7, with a thickness of about 5-10 μm (counting both selective layers). In addition, the effect of operating temperature on the membrane permeances has been studied experimentally; we analyze its influence on the selectivity of the separation process.

Bacterial Cellulose–Polyvinyl Alcohol Based Complex Composites for Controlled Drug Release

Drug-loaded mono- and multilayer composite membranes were prepared. The composites, based on nano-fibrillated bacterial cellulose, nano-powdered bacterial cellulose, and polyvinyl alcohol, all biocompatible and biodegradable, were characterized in terms of basic factors related to drug diffusivity and mass transfer: swelling ability, water solubility, and water vapor permeability. Tetracycline hydrochloride was used in this case as drug model. Drug release was evaluated in an aqueous environment for two concentration levels of the antibiotic, and mathematical modeling was applied to fit experimental data. Tetracycline release was influenced by a membranes’ structure, layers’ composition, and by a membranes’ thickness. Bacterial cellulose nanofibrils proved to be the key factor in achieving suitable drug release profiles. Thus, sustained antibiotic delivery was obtained for several days in the case of multilayer composites. The composites proved drug stability and antibacterial efficiency before and after TC-HCl continuous release for several days.

Designing high-performance pervaporation membranes with hierarchical hydrophobic-hydrophilic coating layers

In this study, a multi-layer pervaporation composite membrane was prepared by spray-coating a hydrophilic layer consisting of poly(allylamine hydrochloride) (PAH)/polyvinyl alcohol (PVA)/trimesic acid (BTA) onto a polyethersulfone (PES) porous substrate. The presence of amine groups facilitated the transport of water molecules, enabling the composite membrane to exhibit excellent water/ethanol separation properties. When a feed solution consisting of 90 ​wt% ethanol and 10 ​wt% water was dehydrated using the PV membrane at 70 ​°C, a flux of 1.46 ​kg ​m−2 ​h−1 with a water/ethanol separation factor of 3300 was realized. In addition, after coating a 267 ​nm silicone rubber layer on top of the membrane, the separation factor was further increased by 70.79 % to 5285, while the flux was slightly decreased by 12.33 % to 1.28 ​kg ​m−2 ​h−1. This was because the hydrophobic silicone rubber layer reduced the water swelling effect of the selective layer and hindered the permeation of ethanol-water coupling molecules, resulting in a reduction in the ethanol flux of the composite membrane and an improvement in the separation factor. This simple but effective method to improve dehydration properties was very useful for fabricating PV composite membranes.

Alumina-PEBA/ PSf Multilayer composite membranes for CO2 separation: experimental and molecular simulation studies

In this research, Polyether block amide (PEBA) containing different loadings of α-Al2O3 particles was deposited on top of the polysulfone (PSf ) supports to form PEBA 1657‒α-Al2O3/PSf multilayer composite mixed matrix membranes (MCMMMs). Multilayer Composite structure was used to overcome the sedimentation of fillers in the polymer matrix. Moreover, alpha phase of the Al2O3 particles was applied to improve the distribution of these particles at higher loadings. SEM, XRD, and FTIR tests were applied to study morphology, crystalline structure, and chemical structure of the membranes, respectively. Gas permeation properties of the membranes were also measured using three different pure gases (CO2, CH4, and N2) at the pressure of 7 bar and temperature of 25 ºC. CO2 permeance and ideal selectivity of CO2/CH4, and CO2/N2 for the optimum MCMMM with 20 wt% loading of α-Al2O3 particles were 25% (117.5 Barrer), 81.5 % (32), and 86.5% (57) higher than that of multilayer composite neat membrane (MCNM), respectively. The molecular simulation results confirmed the results of the experimental studies and approved that the α-Al2O3 particles are right candidates for improving the PEBA performance for CO2 separation.

Mathematical Modeling of the Selective Transport of Singly Charged Ions Through Multilayer Composite Ion-Exchange Membrane during Electrodialysis

The deposition of several alternating anion- and cation-exchange surface layers (layer-by-layer method) is a promising technique for the modification of ion-exchange membranes, which makes it possible to essentially increase their selectivity to singly charged ions. This paper presents a one-dimensional model, which is based on the Nernst–Planck–Poisson equations and describes the competitive transfer of singly and doubly charged ions through a multilayer composite ion-exchange membrane. It has been revealed for the first time that, as in the earlier studied case of a bilayer membrane, the dependence of the specific permselectivity coefficient (P1/2) of a multilayer membrane on the electrical current density passes through a maximum left( {P_{{{1 mathord{left/ {vphantom {1 2}} right. kern-0em} 2}}}^{{max }}} right). It has been shown that an increase in the number of nanosized modification bilayers n leads to the growth of P_{{{1 mathord{left/ {vphantom {1 2}} right. kern-0em} 2}}}^{{max }}, but the flux of a preferably transferred ion decreases in this case. It has been established that P_{{{1 mathord{left/ {vphantom {1 2}} right. kern-0em} 2}}}^{{max }} is attained at underlimiting current densities and relatively low potential drop. The simulated dependences P_{{{1 mathord{left/ {vphantom {1 2}} right. kern-0em} 2}}}^{{max }}(n) qualitatively agree with the known literature experimental and theoretical results.

Multilayered hydrocarbon ionomer/PTFE composite electrolytes with enhanced performance for energy conversion devices

A new multilayered composite membrane was prepared by impregnating a sulfonated poly(arylene ether sulfone) (SPAES) ionomer into a porous polytetrafluoroethylene (PTFE) substrate for application in proton exchange membrane fuel cells (PEMFCs) and water electrolyzers (PEMWEs). The PTFE substrate was treated with n-propyl alcohol to mediate the interfacial interactions between the SPAES solution and PTFE. Using the 10- and 5-μm-thick PTFE substrates, three-layered and five-layered composite membranes were prepared, respectively, to investigate the effect of PTFE thickness on impregnation of the SPAES ionomer. When 5-μm-thick PTFE was applied, the SPAES ionomer was effectively impregnated without noticeable defects, indicating a strong interlocking structure between the two incompatible components. Therefore, the five-layered composite membrane showed enhanced dimensional stability and mechanical properties compared to the SPAES membrane, and the effect of the PTFE on proton conductivity was minimized. Consequently, the cell performances of the five-layered composite membrane were reflected by current densities of 1.71 A/cm2 at 0.5 V and 9.76 A/cm2 at 1.9 V for PEMFC and PEMWE, respectively, corresponding to 44% and 32% increases compared to those of Nafion 212, owing to its smaller membrane resistance. Moreover, the prepared composite membrane presented excellent durability, which resulted in stable wet-dry cyclability and low degradation rates.

Bioactive composite Janus nanofibrous membranes loading Ciprofloxacin and Astaxanthin for enhanced healing of full-thickness skin defect wounds

In this paper, skin-inspired multilayer Janus composite nanofibrous membranes with superhydrophilicity and superhydrophobicity as a wound dressing were designed and prepared to manage and utilize the exudates. Wettability, morphology, in-vitro release, cytotoxicity, antimicrobial activity and healing effect were investigated. Animal experiment and histological analysis confirmed the composite membranes were more effective in improving the healing of full-thickness defect wound, the growth of collagen fibers and collagen deposition. The four-layer composite membranes include the drug-loading layer containing Ciprofloxacin (CIP) and Astaxanthin (ATX) with superhydrophilic surface for self-pumping and drugs backflow, the hydrophobic polyvinylidene fluoride layer for delaying the exudates loss, and the superhydrophobic coating with self-cleaning properties for avoiding adhesion of foreign microorganisms. The exudates were absorbed into the composite membrane and locked in the nanofiber network to avoid dehydration of the wound, meanwhile, CIP and ATX were delivered to the wound bed to effectively inhibit bacterial growth and stimulate tissue regeneration. These results demonstrate that skin-inspired Janus composite nanofibrous membrane is a promising wound dressing for promoting full-thickness skin defect wound healing, displaying its great potential applications in skin tissue engineering.

Toward the truth of condensing-water membrane for efficient biogas purification: Experimental and modeling analyses

Facilitated transport membranes with high CO2/CH4 separation performance under humidified state have shown great prospects for biogas purification. The role of water might include the formation of condensed water film on membrane surface, but it was seldom verified and investigated. In this study, the condensation of water film on polyamide (PA) thin-film composite membrane was performed and regulated. Thanks to the absence of active carrier groups that can reversibly with CO2, the contribution of water to facilitated transport can be neglected, and the truth of condensing-water membrane was allowed to be explored. The PA layer was fabricated by interfacial polymerization with its hydrophilicity tuned by polyvinyl alcohol. The regulation of water film is based on three operational approaches: simple humidifying the feed gas, pre-wetting the membrane, or heating the humidifier. The remarkable increment of selectivity along with the improvement of water-condensing conditions implied the formation of condensed water film. Fortunately, the series of gas permeation data allowed the estimation of water film thickness according to the mass transfer resistance model for multilayer composite membranes. The decline of selectivity over time under elevated pressure was found effective to evaluate the stability of such condensing water membranes. The results show that a polyamide thin-film composite membrane with poor CO2/CH4 selectivity under dry state can achieve rather high performance (CO2 permeance 374 GPU and CO2/CH4 selectivity 31 for 16 days under 3.25 bar) with the aid of a simple condensed water layer. Hopefully, it provides a method to re-evaluate the effect of water on a given facilitated transport membrane, and possibilities of further enhancing its separation performance by fine tuning the condensed water film.