Microporous Films Research Articles

Controllable synthesis of conjugated microporous polymer films for ultrasensitive detection of chemical warfare agents

Nerve agents, one of the most toxic chemical warfare agents, seriously threaten human life and public security. The high toxicity of nerve agents makes the development of fluorescence sensors with suitable limit of detection challenging. Here, we propose a sensor design based on a conjugated microporous polymer film for the detection of diethyl chlorophosphate, a substitute of Sarin, with low detection limit of 2.5 ppt. This is due to the synergy of the susceptible on-off effect of hybridization and de-hybridization of hybrid local and charge transfer (HLCT) materials and the microporous structure of CMP films facilitating the inward diffusion of DCP vapors, and the extended π-conjugated structure. This strategy provides a new idea for the future development of gas sensors. In addition, a portable sensor is successfully integrated based on TCzP-CMP films that enables wireless, remote, ultrasensitive, and real-time detection of DCP vapors.

Effect of 1-MCP Treatment Combined with Laser Microporous Film Packing on the Preservation Effect of Honey Peach Fruit

Effect of 1-MCP Treatment Combined with Laser Microporous Film Packing on the Preservation Effect of Honey Peach Fruit

Regeneration of zeolite membranes deactivated by condensable molecules

A zeolite membrane is a microporous film on a porous substrate that can discriminate molecules in the gas and liquid phases through its pores. Although zeolite pores play a critical role in achieving a high separation performance, they tend to be clogged by condensable molecules during the separation process, resulting in a significant drop in the separation performance. In this study, the thermal regeneration of zeolite membranes deactivated by condensable molecules was investigated to achieve their reusability without significant changes in the separation performance. Silicoaluminophosphate (SAPO-34) and pentasil (MFI) membranes were prepared, and condensable vapors, including water, n-butanol, n-methyl-2-pyrrolidone, and thermally degenerated organic vapors were chosen as the foulants to block the pores of the zeolite membranes. The optimized regeneration temperature differed according to the type of foulant and zeolite framework. Overall, the optimized thermal desorption temperature of every foulant was lower for the MFI membrane because of its larger pores and more hydrophobic surfaces compared to those of the SAPO-34 membrane. For the membranes deactivated by thermally degenerated organic vapors, the pores of the zeolite membranes were opened based on organic solvent treatment followed by thermal desorption. In addition, the MFI membrane was more sensitive to heat than the SAPO-34 membrane; therefore, slight changes in the membrane selectivity were observed depending on the thermal regeneration protocols. This study demonstrated that deactivated zeolite membranes can be regenerated, and excess heat exposure during thermal regeneration can decrease gas selectivity through the creation of nonzeolitic pores.

Efficient Separation of Nd(III) and La(III) Via Supported Liquid Membrane Using EHEHPA (P507) as a Carrier

This work tested an effective and efficient Nd/La extraction and separation via flat-sheet supported liquid membrane. A microporous polypropylene film was used as the solid support for the liquid membrane and P507 as the extractant. The effect of Nd(III) and La(III) concentration in the feed, the concentration of P507, and acid solution concentration in the stripping phase on Nd and La extraction and separation were studied. The results suggest the extraction of La and Nd increases with the initial pH of the feed solution and P507 concentration. Maximum separation factor of 44.25 was obtained at the low P507 concentration of 5% (v/v).Graphical

Hierarchical structure and properties of high‐density polyethylene (HDPE) microporous films fabricated via thermally‐induced phase separation (TIPS): Effect of presence of ultra‐high molecular weight polyethylene (UHMWPE)

AbstractIn this study, HDPE/UHMWPE microporous films were prepared by blending UHMWPE and HDPE with DOP as the diluent via thermally‐induced phase separation (TIPS) method. Morphological studies showed that the phase separation mode of the mixed systems was hardly changed in the presence of UHMWPE. Both average pore size and porosity of the blend films increased firstly and then decreased with increasing UHMWPE content. When UHMWPE content reached 1.5 wt%, both porosity and average pore size of the film reached their maximum values (with a porosity of 84.8% and an average pore size of 0.79 μm). The addition of UHMWPE was found to not only enhance the thermal stability of the HDPE/UHMWPE blend films, but also greatly reduce their thermal shrinkage rate as well as the closed cell temperature, which made the diaphragms containing UHMWPE have good prospect for the application in lithium‐ion batteries (LIBs).

Co-Application of 1-MCP and Laser Microporous Plastic Bag Packaging Maintains Postharvest Quality and Extends the Shelf-Life of Honey Peach Fruit.

Honey peach (Prunus persica L.) is highly nutritious; it is an excellent source of sugars, proteins, amino acids, vitamins, and mineral elements. However, it is a perishable climacteric fruit that is difficult to preserve. In this study, “Feicheng” honey peach fruit was used as a test material to investigate the synergistic preservation effect of 1-methylcyclopropene (1-MCP) and laser microporous film (LMF). The peach fruits were fumigated for 24 h with 2 μL L−1 1-MCP, then packed in LMF. In comparison with the control treatment, 1-MCP + LMF treatment markedly decreased the respiration rate, weight loss, and rot rate of peach fruits. Moreover, the combination of 1-MCP and LMF suppressed the increase in soluble solids (SS) and reducing sugars (RS), as well as the decrease in titratable acid (TA) and ascorbic acid (AsA). The combined application also maintained a high protopectin content and low soluble pectin content; it reduced the accumulation of superoxide anions (O2−) and hydrogen peroxide (H2O2). Except in a few samples, the catalase (CAT) and ascorbate peroxidase (APX) activities were higher when treated by 1-MCP + LMF. Conversely, the phenylalanine deaminase (PAL), peroxidase (POD), lipase, lipoxygenase (LOX), polygalacturonase (PG), β-glucosidase, and cellulase (Cx) activities were lower than in the control. Furthermore, 1-MCP + LMF treatment reduced the relative abundances of dominant pathogenic fungi (e.g., Streptomyces, Stachybotrys, and Issa sp.). The combined treatment improved the relative abundances of antagonistic fungi (e.g., Aureobasidium and Holtermanniella). The results indicated that the co-application of 1-MCP and LMF markedly reduced weight loss and spoilage, delayed the decline of nutritional quality, and inhibited the physiological and biochemical metabolic activities of peach during storage. These changes extended its shelf-life to 28 days at 5 °C. The results provide a reference for the commercial application of this technology.

Improvement of Emulsion Stability and Plugging Performance of Nanopores Using Modified Polystyrene Nanoparticles in Invert Emulsion Drilling Fluids.

Drilling fluid invasion and pressure transmission caused by the development of micropores and fractures in shale oil and gas formations are the major factors contributing to wellbore instability during drilling using oil-based drilling fluids (OBFs). In this study, a modified polystyrene latex (MPL) material was synthesized through emulsion polymerization and was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), particle size analysis, scanning electron microscopy (SEM) observations, and contact angle testing. The influence of the MPL on the stability of a water-in-oil emulsion was analyzed via sedimentation observations and electrical stability tests. The effects of the MPL on the plugging mechanism of white oil and water-in-oil emulsions were evaluated using 0.1–1.0 μm micro-porous filtration films. The experimental results revealed that the MPL has a favorable thermal stability, with an initial thermal decomposition temperature of 363°C, a median particle size (D50) of 233 nm, and a three-phase contact angle of 103.5°. The MPL can enhance the sedimentation stability of an emulsion to a considerable extent and can improve the electrical stability (ES) of the emulsion, which is conducive to the stability of OBFs. Due to the deformability of the MPL, it has a wide range of adaptations for micro-scale pores and fractures. In both the white oil and water-in-oil emulsions, the MPL can reduce the filtration loss through microporous membranes with pore sizes of 0.1–1.0 μm to within 10 ml. This paper details the methodology of the synthesis of nanomaterials that can effectively plug a formation’s nanopores and fractures; thereby, stabilizing OBFs.

Aerosol-Assisted Deposition for TiO2 Immobilization on Photocatalytic Fibrous Filters for VOC Degradation.

Atomization and spraying are well-established methods for the production of submicrometer- and micrometer- sized powders. In addition, they could be of interest to the immobilization of photocatalytic nanoparticles onto supports because they enable the formation of microporous films with photocatalytic activity. Here, we provide a comparison of aerosol-assisted immobilization methods, such as spray-drying (SD), spray atomization (SA), and spray gun (SG), which were used for the deposition of TiO2 dispersions onto fibrous filter media. The morphology, microstructure, and electronic properties of the structures with deposited TiO2 were characterized by SEM and TEM, BET and USAXS, and UV-Vis spectrometry, respectively. The photocatalytic performances of the functionalized filters were evaluated and compared to the benchmark dip-coating method. Our results showed that the SG and SA immobilization methods led to the best photocatalytic and operational performance for the degradation of toluene, whereas the SD method showed the lowest degradation efficiency and poor stability of coating. We demonstrated that TiO2 sprays using the SG and SA methods with direct deposition onto filter media involving dispersed colloidal droplets revealed to be promising alternatives to the dip-coating method owing to the ability to uniformly cover the filter fibers. In addition, the SA method allowed for fast and simple control of the coating thickness as the dispersed particles were continuously directed onto the filter media without the need for repetitive coatings, which is common for the SG and dip-coating methods. Our study highlighted the importance of the proper immobilization method for the efficient photocatalytic degradation of VOCs.

Physical structure, TD-DFT computations, and optical properties of hybrid nanocomposite thin film as optoelectronic devices

HCl doped-copolymer of ortho phenylene diamine and meta phenylene diamine was prepared by using oxidative polymerization method with ferric chloride as an oxidizing agent in the existence of sodium dedocyl sulphate as a soft template. The microporous structure thin films of hybrid copolymer/ZrO2 nanocomposite [copolymer/ZrO2]NC were fabricated using a physical vapor deposition (PVD) method. The effect of addition of zirconium oxide nanoparticles [ZrO2]NPs on the physical properties of the copolymer was discussed in the light of crystallinity and optical properties. The average crystallite size of [ZrO2]NPs is around 40 nm. The copolymer showed an absorbance of 1.18 at the wavelength (λ) 374 nm, which increased to 1.26 at λ = 440 nm after glycine addition, also increased to 1.53 at λ = 486 nm after [ZrO2]NPs loading. Also, the significant changes in the absorption index and indirect/direct bandgap of the copolymer have been detected. The materials Studio 7.0 program on TDDFT/DMol3 was used to optimize the molecular structure and perform the frequency calculations for the crystal models and isolated molecules. The DFT-Gaussian09W-vibration values are quite similar to the experimental data either in the structure or in the optical properties. The improvements in optical properties were achieved and revealed the possibility of using the hybrid nanocomposite films in the polymers solar cell application.

Preparation of Microporous Film Composed of Polypropylene Containing β-Form Nucleating Agent

Preparation of Microporous Film Composed of Polypropylene Containing β-Form Nucleating Agent

Physical properties and DFT calculations of the hybrid organic polymeric nanocomposite thin film [P(An+o-Aph)+Glycine/TiO2/]HNC with 7.42% power conversion efficiency

Copolymer of aniline and ortho aminophenol was prepared by using the oxidative polymerization method with ferric chloride as an oxidizing agent in the occurrence of polyethylene glycol (Mol. Wt. 200) as a soft template. The microporous structure thin films were fabricated from the hybrid material of titanium oxide/copolymer (2-aminophenol and aniline) + glycine [P(An+o-Aph)+Gl/TiO2]HNC via a physical vapor deposition (PVD) method. The effect of the addition of glycine and TiO2 nanoparticles (NPs) on the physical properties of copolymer [P(An+o-Aph)] was discussed in light of the study of the crystallinity and optical properties. The addition of glycine increases the crystallinity of the resulting blend with the copolymer. The average crystallite size of TiO2 is ≈ 25 nm. The interaction between the blend and TiO2 was physical. The copolymer showed an absorbance of 1.18 at the wavelength (λ) 374 nm, which increased to 1.26 at λ= 440 nm after glycine addition, also increased to 1.53 at λ= 486 nm after TiO2 loading. Due to glycine blending and TiO2 addition, significant changes in the absorption index and indirect/direct bandgap of the copolymer have been detected. The materials Studio 7.0 program on TDDFT/DMol3 was used to optimize the molecular structure and perform the frequency calculations for the crystal models and isolated molecules. The DFT-Gaussian09W-vibration values are quite similar to the experimental data either in the structure or in the optical properties. The power conversion efficiency (η) of the blend Au/[P(An+o-Aph)+Gl]B/p-Si/Al heterojunction is 5.30 %, which increased to η=7.42% by loading the [TiO2]NPs to blend. The improvements in optical illuminations properties suggest the use the hybrid nanocomposite films in the polymers solar cell application.

Separation of Crystal Violet Dye from Wastewaters by Using Supported Liquid Membrane Technology

The current study enumerates the use of supported liquid membrane (SLM) technology to remove and recover crystal violet dye from wastewaters. The management of textile industry waste effluents is one of the main concerns of environmental health experts due to having excessive concentrations of dyes and resistance to biodegradation. Liquid membranes offer an affordable and green method for the selective removal of dyes from aqueous solutions. To create a liquid membrane, refined and edible vegetable oils were supported on microporous polymeric films of polypropylene (PP1E). Various parameters influencing transport, such as pH range in the feed solution, initial dye concentration, acid concentration in the strip solution, oil viscosities, and membrane lifetime, have been studied. The maximum flux value ( 1.7 × 10 − 5 mg/cm2/s) for crystal violet dye was obtained with sunflower oil-supported membrane at a pH of 12 in the feed solution and a concentration of 0.3 M hydrochloric acid in the strip solution. Under ideal conditions, the maximum amount of dye was transported within 6 hours. Studies on membrane stability and morphology revealed that the flux remained constant up to about 24 hours and then decreased gradually. Morphological studies showed that this may be attributed to deformation of pores shape and gradual clogging.

Comparative Evaluation of Graphene Nanostructures in GERS Platforms for Pesticide Detection.

Graphene-enhanced Raman scattering (GERS) produces enhancement of the Raman signal, which is based on chemical rather than electromagnetic mechanism such as in the surface-enhanced Raman scattering. Graphene oxide, amino- and guanidine-functionalized graphene oxide, exfoliated graphene, and commercial graphene nanoplatelets have been used to investigate the GERS response with the change of graphene properties. Different graphene nanostructures have been embedded into organic–inorganic microporous films to build a platform for the fast and sensitive detection of pesticides in water. The graphene nanostructures vary in the number of layers, lateral size, degree of oxidation, and surface functionalization. The GERS performances of the graphene nanostructures cast on silicon substrates and embedded in the nanocomposite films have been comparatively evaluated. After casting a few droplets of the pesticide aqueous solution on the graphene nanostructures, the Raman band enhancements of the analytes have been measured. In the nanocomposite films, the characteristic Raman bands originating from pesticides such as paraoxon, parathion, and glyphosate could be traced at concentrations below 10–7, 10–5, and 10–4 M, respectively. The results show that the surface functionalization reduces the GERS effect because it increases the ratio between the sp3 carbon and sp2 carbon. On the other hand, the comparison among different types of graphenes shows that the monolayers are more efficient than the few-layer nanostructures in enhancing the Raman signal.

Boosted electrolytic hydrogen production at tailor-tuned nano-dendritic Ni-doped Co foam-like catalyst

Herein, the dynamic hydrogen bubble template (DHBT) method is used to design a microporous nano-dendritic Co film with foam-like morphology. Subsequently, Co film is doped by Ni and further electropassivated in 1.0 M KOH to develop metal/oxygenated metal interfaces, leading to a prompt water dissociation step in alkaline HER. The electropassivated nano-dendritic Ni-doped Co film is characterized by SEM, HR-TEM, XRD, EDS-mapping, ICP-OES, and XPS analyses. The electrochemical measurements show that the proposed electrocatalyst exhibits a striking activity, with an overpotential of −50 mV while operating at 10 mA cm-2, outperforming its precursors and surpassing/approaching the activity of benchmark and precious-metals-fabricated catalysts. Interestingly, the electropassivated Ni-doped Co film shows a marked enhancement towards the HER compared to the electropassivated Co film, indicating that the oxygenated Ni species play a crucial role by preserving the active metal/oxygenated metal interfaces. The obtained results introduce a promising robust catalytic material for electrolytic hydrogen production in alkaline media.

A Nonflammable and Thermally Stable Polyethylene/Glass Fiber−Magnesium Hydroxide/Polyethylene Composite Separator with High Mechanical Strength and Electrolyte Retention to Enhance the Performance of Lithium‐Ion Batteries

To overcome the shortcomings in the thermal stability and electrolyte wettability when a commercial polyethylene (PE) separator is used alone, a PE/glass fiber (GF)−Mg(OH)2/PE composite (PGMP) separator is developed, and the electrochemical and safety performance of lithium‐ion batteries is effectively enhanced. The PGMP separator is prepared by soaking a mixed dispersion solution of polyacrylate and Mg(OH)2 into the GF fabric substrate and subsequently bonding the PE microporous film on both substrate sides. Compared with the PE separator, PGMP separator exhibits enhanced mechanical strength (≥250 MPa), ionic conductivity, and electrolyte wettability. Furthermore, there is almost no shrinkage when this PGMP is annealed at 350 °C for 30 min. The nail penetration, impact, overcharge, and adiabatic rate calorimeter tests of LiNi0.5Co0.2Mn0.3O2/graphite pouch cell with a nominal capacity of 2500 mAh show that the PGMP separator effectively improves the safety performance. The thermal runaway temperature of the pouch cells is increased from about 120 to 146 °C, and the electrolyte wettability ability of the PGMP separator gives the cell a capacity retention of 85% after 500 cycles at 1.0 C. Combined with the advantages, it is indicated that this PGMP separator has great potential in commercial applications.

Electrochemical Preparation of Highly Oriented Microporous Structure Nickel Oxide Films as Promising Electrodes in Urea Oxidation

Abstract Highly oriented microporous nickel oxide films were prepared through the simple and fast anodization of nickel foils at 30 V, followed by calcination at 400 °C. Low concentrations of ammonium chloride and potassium hydroxide solutions, which were dispersed in ethylene glycol, were used as electrolytes. Microporous dimensions and large surface areas of the films were obtained by using both electrolytes. The ammonium chloride system provided a highly oriented microporous structure with excellent distribution of pores at the surface of nickel foil. On the contrary, it was not uniform in the potassium hydroxide system. Furthermore, cyclic voltammetry of the microporous films in alkaline solutions containing urea showed the highest oxidation currents at the nickel oxide films prepared in the ammonium chloride system. This nickel oxide film also showed excellent stability of the current responses, indicating that the method has potential to be applied in electrode preparation, especially urea oxidation.

Sono-Cavitation and Nebulization-Based Synthesis of Conjugated Microporous Polymers for Energy Storage Applications.

Conjugated microporous polymers (CMPs) are promising energy storage materials owing to their rigid and cross-linked microporous structures. However, the fabrication of nano- and microstructured CMP films for practical applications is currently limited by processing challenges. Herein, we report that combined sono-cavitation and nebulization synthesis (SNS) is an effective method for the synthesis of CMP films from a monomer precursor solution. Using the SNS, the scalable fabrication of microporous and redox-active CMP films can be achieved via the oxidative C-C coupling polymerization of the monomer precursor. Intriguingly, the ultrasonic frequency used during SNS strongly affects the synthesis of the CMP films, resulting in an approximately 30% improvement in reaction yields and ca. 1.3-1.7-times enhanced surface areas (336-542 m2/g) at a high ultrasonic frequency of 180 kHz compared to those at 120 kHz. Furthermore, we prepare highly conductive, three-dimensional porous electrodes [CMP/carbon nanotube (CNT)] by a layer-by-layer sequential deposition of CMP films and CNTs via SNS. Finally, an asymmetric supercapacitor comprising the CMP/CNT cathode and carbon anode shows a high specific capacitance of 477 F/g at 1 A/g with a wide working potential window (0-1.4 V) and robust cycling stability, exhibiting 94.4% retention after 10,000 cycles.

Effect of surface hydrophobisation on the properties of a microporous phenylene-bridged organosilicate film

This study aims hydrophobisation of a microporous phenylene-bridged organosilicate film via its surface modification with hexamethyldisilazane (HMDS) vapour to adapt it for use as a low dielectric constant material for advanced microelectronics technology. The microporous organosilicate film was spin-coated with 1,4-bis (triethoxysilyl) benzene, followed by soft baking at 120–200 °C and annealing at 390 °C in N2. Subtractive porosity was added using a sacrificial template — Brij® L4. This 1,4-phenylene-bridged film possessed a large Young's modulus and small pore size. However, due to steric effects during the film formation, a large amount of unreacted silanol remained on the surface. The HMDS-induced hydrophobisation reduced the number of residual silanols and adsorbed water molecules, despite the small pore size. A decrease in the hydrophilicity of the film surface led to an increase in the WCA value as well as a decrease in the dielectric constant and dielectric loss tangent. Ellipsometric porosimetry showed that the open porosity decreased without changes in the pore size distribution as a result of silylation by the HMDS vapour. However, the Fourier transform infrared spectra showed limited time-dependant temperature stability of the –CH3 groups introduced by the HMDS vapour treatment. The decrease in open porosity during the heat treatment of the hydrophobised film was significantly reduced because of the strengthening of the pore walls. Consequently, this film demonstrated lower shrinkage and larger Young's modulus.

Development of a gas-permeable bag photobioreactor for energy-efficient oxygen removal from algal culture

Closed photobioreactors are ideal for the production of high-purity and high-value microalgal and cyanobacterial products. However, dissolved oxygen accumulation in closed reactors is detrimental to the growth. Conventional aeration for oxygen removal comprises up to 40% of the total culture cost, and energy-efficient dissolved oxygen removal is demanded. In this study, a novel gas-permeable bag photobioreactor was developed by the incorporation of a gas-permeable film. A hydrophobic microporous film was the most effective for both oxygen permeability and cost compared to silicone or fluororesin. The microporous film was placed on the backside of the reactor as an irradiation reflector. In a culture of Euhalothece sp., less than half of the steady-state dissolved oxygen concentration was demonstrated in the gas-permeable reactor than a non-permeable reactor. The gas-permeable reactor exhibited an oxygen transfer coefficient of 0.084 min−1 under continuous mixing, which is high enough to maintain approximately 300% dissolved oxygen concentration with 58 mg L−1 h−1 biomass productivity without aeration (equivalent to 1.4 g L−1 d−1 under 24-h light). The estimated energy requirement for the gas-permeable reactor can be less than 1% of the aerated reactor of the same size. These results suggested the effectiveness of the gas-permeable reactor for energy-efficient algal mass culture.

N-doped carbon-coated freestanding Fe film with sea urchin-like micro/nanoporous structure for efficient oxygen evolution reaction catalyst

Nitrogen-doped carbon-coated freestanding Fe film with sea urchin-like 3D micro/nanoporous structure as oxygen evolution reaction (OER) catalyst is prepared for the first time based on the electrodeposition of 3D microporous Fe film, sea urchin-like FeTCNQ Metal-Organic Frameworks (MOFs) coating synthesis (Fe@ FeTCNQ), and FeTCNQ pyrolysis to form N-doped carbon coating (Fe@C(N)). Due to the synergistic effect of multiple structures, the sea urchin-like porous Fe@C(N) film possesses high inherent catalytic activity, large active area and good wettability, so it exhibits outstanding electrocatalytic activity and long-term stability for OER. The Tafel slope and overpotential at 10 and 200 mA cm[Formula: see text] of Fe@C(N) film for OER are 75 mV dec[Formula: see text], 77 and 453 mV in 1 M NaOH, respectively, which are much lower than those (129 mV dec[Formula: see text], 108 and 595 mV) of 3D microporous Fe film.