Vapor-induced Phase Separation Research Articles

Membranes of Amphiphilic Polyamide 1012 Prepared via Mixed ‘Non-solvents’ Evaporation Induced Phase Separation

Membranes of Amphiphilic Polyamide 1012 Prepared via Mixed ‘Non-solvents’ Evaporation Induced Phase Separation

Highly sensitive and stretchable CB/GNPs-TPU strain sensor with porous microstructure for multifunctional strain sensing

Multifunctional flexible strain sensors have garnered significant attention in recent years, particularly in the fields of smart wearable devices and human health monitoring. However, the trade-off between high sensitivity and a wide strain range limits their practical applications. This study presents a porous TPU/CB framework prepared using a water vapor-induced phase separation method, which can deform like a spring when stretched, thereby providing the sensor with a greater strain range. The graphene nanoplatelets (GNPs) were subsequently incorporated into the pores of the porous framework through ultrasonic treatment, which enhanced the sensor's sensitivity while preventing increased brittleness caused by the aggregation of conductive fillers. This structure establishes a stable conductive network, enabling the sensor to achieve high sensitivity (GF = 5902.4) across a wide strain range (327 %) while also demonstrating excellent stability and durability (over 7000 stretching/releasing cycles). The sensor can detect not only simple limb movements, such as bending of the arms and knees but also subtle muscle activities, including facial expressions and throat vocalization, thus bringing excellent human-computer interaction experience. These remarkable features position the sensor for promising applications in smart wearables and human health monitoring.

Optimizing PES microfiltration membranes for sterile filtration: A comparative study of polydopamine coating in acidic and basic conditions to minimize protein adsorption

The increasing need for effective sterile filtration in the pharmaceutical industry calls for advancements in microfiltration (MF) membrane technology that can effectively reduce fouling and preserve essential protein products. Our study highlights the crucial role of improving the hydrophilicity throughout the entire membrane, not just on the surface, to decrease both protein adsorption and fouling. We have developed a facile but effective method for producing hydrophilic porous polyethersulfone (PES) MF membranes using vapor-induced phase separation (VIPS) followed by a hydrophilic coating. By meticulously adjusting the vapor exposure time, we fabricated two specific types of symmetric membranes: a standard one with a mean pore size of 0.22 μm and another designed with slightly larger pores for the subsequent polydopamine (PDA) coating. All membranes developed in this study showed an outstanding sterilization performance (over 99.99999 % bacteria rejection) due to the absence of defects. Our comparative studies of PDA coating in both acidic and basic environments revealed that the PDA-modified membranes in a Tris-HCl buffer (pH 8.0) (PDA-b-PES2M) outperform others in performance of protein microfiltration. While the membrane modified under acidic conditions underwent a gradual degradation of PDA leading to a poor filtration performance, the PDA-b-PES2M membranes showcased remarkable anti-fouling properties, greatly minimizing the adsorption of bovine serum albumin (BSA) and simplifying the removal of adsorbed materials. Our optimized membrane has a great potential for sterile filtration applications where minimizing protein loss is crucial.

Fabrication of CNC-AC bionanosorbents from the residual mass of Magnolia champaca l. Bark after methanol extraction for wastewater treatment: Continuous column adsorption study

In this current study, a new class of multifunctional biobased ecofriendly nanosorbents namely crystalline nanocellulose-activated char (CNC-AC) nanosorbents were fabricated by employing a much more innovative and beneficial solvent evaporation induced phase separation (EIPS) technique. While the crystalline nanocellulose (CNC) were extracted from a very much new, innovative, and beneficial agrowaste source namely banana tree (M. oranta) rachis fibers by conducting a series of chemical treatments like scouring, alkali treatment, bleaching, and acid hydrolysis reactions. Additionally, the biochar were synthesized from the residual mass of Magnolia champaca L. barks after methanol extraction and functionalized by 30 % H3PO4 to improve their overall properties. Besides these the fixed-bed continuous column adsorption study were carried out by optimizing the various influential factors such as preliminary concentration and flow rates of the inlet wastewater solution, along with the nanosorbent bed heights into the applied column. For better understanding the overall physicochemical, thermomechanical, and morphostructural behavior of the newly fabricated polyfunctional CNC-AC bionanosorbents the samples were characterized by conducting FTIR-ATR, FESEM, BET, XRD, TGA analysis. Meanwhile the treated and nontreated water specimens were examined by conducting AAS and UV–vis-NIR techniques. The obtained results recommended that the newly produced CNC-AC nanosorbents have contained a quite number of active edges/binding sites along with substantial sp. surface area (around 316.95 m2/g). Additionally, they possessed a crystallinity index about 59.98 ± 0.027 %, greater thermal steadiness up to 600 °C, and outstanding 2D honeycomb-like mesoporous peripheral surface microstructure with a promising spherical shapes and smaller size nearly 5–10 nm. The highest removal capacity were found at 538.91 mg/g and 455.70 mg/g for Pb2+ and CR respectively. Additionally, for better understanding the experimental breakthrough curves (BTC) were evaluated by several well established column models while the maximum R2 value was found around 0.999 for the Thomas model and reduced chi squire (χ2) value was around 0.0001.

Multilayer porous poly (vinylidene fluoride)/MXene/cobalt ferrite composites with ternary gradients for electromagnetic wave absorption

A composite material with a high potential for absorbing electromagnetic waves (EMW) was obtained by selecting poly (vinylidene fluoride) (PVDF) as the matrix, MXene as the conductive filler, and cobalt ferrite (CoFe2O4) as the magnetic filler. A layer-by-layer assembly strategy involved hot pressing and sequential blade coating, followed by vapor-induced phase separation, was used to implement the preparation of PVDF/MXene/CoFe2O4 (PMC) composites. The process facilitates the formation of a well-organized multilayer porous framework, providing a gradient of positive conductivity, negative magnetism, and porosity within the composites. Incorporating distinct multilayer, porous, and gradient structures into a single composite led to exceptional impedance matching (Z), with an area percentage of up to 8.4 % in the optimal range of 0.8 to 1.2. Furthermore, the multiple interfaces formed by the various components, multilayer structure, and porous configuration significantly enhanced the EMW attenuation capability, with the attenuation constant reaching as high as 274. Consequently, the PMC composite demonstrated outstanding performance with a minimal reflection loss (RLmin) of −56.5 dB, a specific RLmin of 23.5 dB/mm, and the broadest effective absorption bandwidth of 3.2 GHz. The combination of the competitive EMW absorption capability, low density, flexibility, adequate tensile strength, and amphiphilic Janus surface may significantly broaden the application scenarios of PMC composites.

Self‐cleaning films of biopolymer polyhydroxybutyrate with different semiconductors incorporation: Development, characterization, and photocatalytic activity evaluation

AbstractSelf‐cleaning hydrophobic films were developed using polyhydroxybutyrate (PHB), enhanced with titanium dioxide (TiO2), bismuth oxyiodide (BiOI), and a BiOI/α‐Fe2O3 heterojunction. This is the first study to analyze the photoactivity of BiOI and BiOI/α‐Fe2O3 immobilized into PHB. Alternative solvents for dissolving PHB were investigated. Additionally, formation methods such as casting in Petri dishes, as well as controlled thickness casting through non‐solvent‐induced phase separation (NIPS), and evaporation‐induced phase separation (EIPS), were employed and compared. Despite differing morphologies, both NIPS and EIPS films exhibited similar photocatalytic activity, suggesting that only the catalyst on the external surface of the film is active. The highest pseudo first‐order apparent kinetic constant (0.1468 ± 0.0015 min−1 g−1) was found in films with the lowest polymer and catalyst concentrations analyzed (5% and 3% ). A double‐layer film preparation method was proposed to enhance photocatalytic activity, resulting in a 70% increase in the kinetic constant (0.2506 ± 0.0019 min−1 g−1). Double‐layer composite films with BiOI and BiOI/α‐Fe2O3 showed photocatalytic activity comparable to TiO2 under UV–visible light. Furthermore, their photocatalytic activity under visible light was confirmed, unlike TiO2, which exhibits a negligible kinetic constant in this wavelength range.

Electrospun Fiber Surface Roughness Modulates Human Monocyte-Derived Macrophage Phenotype.

Injuries to fibrous connective tissues have very little capacity for self-renewal and exhibit poor healing after injury. Phenotypic shifts in macrophages play a vital role in mediating the healing response, creating an opportunity to design immunomodulatory biomaterials which control macrophage polarization and promote regeneration. In this study, electrospun poly(-caprolactone) fibers with increasing surface roughness (SR) were produced by increasing relative humidity and inducing vapor-induced phase separation during the electrospinning process. The impact of surface roughness on macrophage phenotype was assessed using human monocyte-derived macrophages in vitro and in vivo using B6.Cg-Tg(Csf1r-EGFP)1Hume/J (MacGreen) mice. In vitro experiments showed that macrophages cultured on mesh with increasing SR exhibited decreased release of both pro- and anti-inflammatory cytokines potentially driven by increased protein adsorption and biophysical impacts on the cells. Further, increasing SR led to an increase in the expression of the pro-regenerative cell surface marker CD206 relative to the pro-inflammatory marker CD80. Mesh with increasing SR were implanted subcutaneously in MacGreen mice, again showing an increase in the ratio of cells expressing CD206 to those expressing CD80 visualized by immunofluorescence. SR on implanted biomaterials is sufficient to drive macrophage polarization, demonstrating a simple feature to include in biomaterial design to control innate immunity.

A green bulk modification for imparting a green VIPS membrane with antifouling properties

BackgroundMembrane preparation and membrane modification processes have long involved the use of toxic solvents. The present work proposes to only use envrionmentally-friendly solvents for both the fabrication and the surface modification of hydrophobic microfiltration membranes. In addition, coating processes for membrane modification are essentially surface modification processes. However, spray-coating may be a suitable method for both surface and bulk modification. MethodsAfter dissolving poly(vinylidene fluoride) in dimethylsulfoxide, membranes were formed by the vapor-induced phase separation process, and then modified using an aqeous solution of an amphiphilic copolymer containing poly(ethylene glycol) methyl ether methacrylate units. Then, a variety of physicochemical techniques were employed to characterize the membrane structure and prove the effectiveness of the surface/bulk modification. Antifouling tests in static and dynamic conditions were conducted. Significant findingsIt is possible to reduce the water contact angle of the top surface of the membrane from 135° to 0° and that of the bottom surface from 126° to 0° within <10 s, indicating successful hydrophilization of the membrane on the one hand, and top-to-bottom modification, despite solely exposing the top surface to the spray, on the other hand. This conclusion was confirmed by deidcated surface chemistry analyses. Besides, the membranes maintained their original highly porous and symmetric structure with light effects on surface porosity and pore size following the spray-coating process. The drasting improvement of hydrophilicity resulted in effective mitigation of fibrinogen adsorption (reduced by 85 %) and Escherichia coli adhesion (reduced by 86 %). Fouling during cyclic filtration involving a bacterial suspension was also effectively reduced with a flux recovery ratio of 53 % (against 37 % for a commercial hydrophilic membrane) and an irreversible flux decline ratio of 47 % (against 63 % for a commercial hydrophilic membrane) in the conditions of the test.

Electrothermal composite membranes of PVDF-g-IL embedded in steel mesh: Fabrication via VIPS and separation of water-in-perfluoropolyether emulsion with high-viscosity

In this work, the electrothermal composite membranes of PVDF-g-IL (i.e., polyvinylidene fluoride grafted with ionic liquid) embedded in steel mesh (PEISM) have been fabricated via vapor induced phase separation (VIPS). In PEISM, both PVDF-g-IL and steel mesh play important roles in the separation of water/oil. On one hand, the location of PVDF-g-IL among mesh wires contributes to nanopores and special wettability. On the other hand, the steel mesh provides not only mechanical support, but also a platform for electrothermal conversation. Relative to the reference (PVDF-g-IL coating mesh wires), PEISM exhibits the lower magnitudes of pore size and the higher electrothermal power density. The former contributes to the successful separation of water-in-PFPE (perfluoropolyether, with high-viscosity) emulsion while the latter accounts for the significant decrease of fluid viscosity. The combination of them endows PEISM with the excellent permeability and selectivity in the separation of water/PFPE emulsion. Furthermore, both flux and rejection ratio have been improved remarkably upon increasing separation temperature with the help of electrothermal effect. The higher permeability comes from the lower viscosity of PFPE while the superior selectivity is a direct consequence of coalesced water droplets in PFPE matrix resulting from their enhanced mobility at high temperatures. Our results open a novel avenue for the fabrication of electrothermal composite membranes as well as their application in the separation of water/oil system with high-viscosity.

Forward osmosis zwitterionic membranes for platelet concentration – Evaluation of the feasibility of the concept

This study focuses on the development of forward osmosis (FO) membranes tailored for platelet and growth factor enrichment applications while maintaining minimal activation throughout the process. The FO membrane structure comprises a polyacrylonitrile (PAN) layer, fabricated using vapor-induced phase separation (VIPS), atop a polyethylene terephthalate (PET) substrate. Then, a polyamide (PA) layer was formed through interfacial polymerization (IP) at the PAN layer interface. The PET side of the membrane was further enhanced with coatings of antifouling copolymers, based on poly(ethylene glycol) methyl ether methacrylate (PEGMA) alone or both PEGMA and zwitterionic sulfobetaine methacrylate (SBMA). In a first step, the formation of each layer was optimized. The structure of the PAN layer was adjusted through the polymer concentration (15 wt%) and the exposure time to vapors (15 min) during the VIPS step. The PA layer was optimized by adjusting the curing temperature to 70 °C. The antifouling copolymer was selected by conducting protein adsorption tests. Subsequently, these tailored FO membranes were employed in the enrichment of plasma proteins, growth factors, and platelets from platelet-rich plasma. It is shown that the membrane modified with a copolymer made of butyl methacrylate (BMA), PEGMA and SBMA, referred to as poly(BMA-r-PEGMA-r-SBMA), enabled to reach a Human Serum Albumin concentration factor of 1.32 and a platelet concentration using PRP of 2.4. Despite partial platelet activation (12 %) due to the high cell concentration, the platelet content is much higher than in PRP or whole blood, which could benefit platelet-based therapies. In addition, the system can be applied to the concentration of growth factors, with PDGF and VEGF concentration factors of 1.92 and 2.58, respectively, which could contribute to the advancement of regenerative medicine.

PVDF/lithiated sulfonated poly (ether ether ketone) blend coated PE separators for high-performance lithium metal batteries

Ionic conductivity and lithium ion transference number (tLi+) of electrolytes are essential parameters governing the performances of high energy density lithium metal batteries. Although the importance of tLi+versus ionic conductivity has been theorized by simulation, the systematically experimental study of their respective effects on lithium dendrite suppression and battery performances is rarely carried out. Here, a series of polyvinylidene fluoride and lithated sulfonated poly (ether ether ketone) blend (PVDF/SPEEK-Li) coated polyethylene (PE) separators with exactly the same composition but different pore morphologies are fabricated by vapor and non-solvent induced phase separation. The effects of sulfonate group–ion interaction and pore morphologies on ionic conductivity and tLi+ of the electrolytes are studied. The performances of lithium metal batteries can be obviously improved by subtle increase of the tLi+, especially at high charge rates and even with a decrease in conductivity. Even at a high current density of 3 C, the PVDF/SPEEK-Li coated PE separator assembled lithium metal battery using a LiFePO4 cathode with a mass loading of 10.5 mg cm−2 can run stably for 200 cycles with a capacity retention of 79 %, which is superior to the PE separator assembled battery with a life of only 55 cycles.

Study of Manipulative In Situ Pore-Formation upon Polymeric Coating on Cylindrical Substrate for Sustained Drug Delivery.

Herein, the micro-porous polylactic acid coating applied on the surface of the cylindrical substrate is fabricated by a novel in situ pore-formation strategy based on the combinational effect of breath figure (BF) and vapor-induced phase separation (VIPS) processes. Under the condition of high environmental humidity, solvent pair of chloroform and dimethylformamide is employed for post-treatment onto pre-formed PLA coating to induce the pore-formation following the mechanism of BF and VIPS, respectively. A composite porous structure with both cellular-like and bi-continuous network morphologies is obtained. By tunning the experimental factors including the ratio of the solvent pair, environmental humidity, and temperature, morphological manipulation upon the pore morphology can be facilely achieved based on the control of mechanism transition between BF and VIPS. Paclitaxel is used as a model drug and loaded into the porous coating by the wicking effect of post-immersion. Coatings with different morphological features show varying drug loading and release capacities. The 28-day release test reveals dynamic release profiles between different coating samples, with the total release rate ranging from 35.70% to 79.96%. Optimal loading capacity of 19.28µg cm-2 and 28-day release rate of 35.70% are achieved for the coating with composite BF-VIPS structure. This research established a cost-efficient strategy with high flexibility in the structural manipulation concerning the construction of drug-eluting coating with the feature of manipulative drug delivery.

Surface Grafting of Magnetic Carbon Nanotubes and Their Vertical Alignment in PVDF Asymmetric Ultrafiltration Membranes for Fast Nanochannel Construction

The application of carbon nanotubes (CNTs) in water treatment membranes can increase the permeability and selectivity of the membranes. However, traditional CNTs are usually affected by van der Waals forces, which makes them prone to agglomerate in polymer membranes, and their non-directional arrangement in the membranes limits their transport efficiency as water channels in the membranes. In this paper, a reversible addition-fragmentation chain transfer (RAFT) polymerization method was used to synthesize propargyl methacrylate - random copolymerization - poly (ethylene glycol) methacrylate - block - polymethyl methacrylate [P(PgMA-r-PEGMA) -b-PMMA]. The P(PgMA-r-PEGMA)-b-PMMA grafting rate was 60.4% on the surface of magnetic sulfhydryl functionalized carbon nanotubes (mCNTs-SH) by click-reaction grafting. Poly (vinylidene fluoride) (PVDF)/CNTs composite ultrafiltration membranes were prepared using vapor-induced phase separation (VIPS) combined with magnetic field arraying. When the mCNTs-g-P(PgMA-r-PEGMA)-b-PMMA were vertically aligned in the PVDF membrane through a magnetic field, the effective construction of the vertical nanochannels was realized, and an increased purified water flux from 25.6 LMH to 35.8 LMH, with the composite ultrafiltration membranes was obtained. In addition, the membranes also showed excellent hydrophilicity, mechanical properties, and polyethylene glycol 1200 (PEG1200) rejection. The water contact angle was reduced from 105° to 79°, the rejection of PEG1200 was increased from 44% to 91% of the 0.5 g/L PEG aqueous solutions, and excellent mechanical properties (tensile strengthes up to 9.3 MPa) were achieved. By designing the interface structure of the CNTs and studying the orientation of the CNTs in PVDF membranes, this work provides a new research idea for the field of water treatment ultrafiltration membranes.

Unlocking the potential of zwitterionic vapor-induced phase separation membranes synthesized from maleic anhydride in polyvinylidene fluoride-based systems for antifouling applications

This work presents an approach to form zwitterionic porous poly(vinylidene fluoride) (PVDF) membranes fabricated by vapor-induced phase separation (VIPS). The reaction between maleic anhydride groups, incorporated initially in the casting solution by blending styrene maleic anhydride (SMA), with 3-((3-aminopropyl)dimethylammonio)propane-1-sulfonate led to the desired zwitterionic moieties. XPS and FTIR analyses confirm the functionalization of the membrane. SEM analyses revealed that it did not have any major impact on the membrane morphology deemed to be close to bicontinuous. While the mean pore size of the virgin membrane was 0.57 μm, it increased to 0.85 μm suggesting the pore-forming effect of SMA during the phase-inversion process. Hydration was significantly enhanced, attributed to the zwitterionic groups on the one hand, but also to the formation of carboxylic acid and amide groups following the ring-opening reaction. It led to significant resistance to bacterial attachment as tested with 4 strains of bacteria including Escherichia coli, Stenotrophomonas maltophilia, Staphylococcus aureus and Streptococcus mutans (>99 % reduction for each). Applied in cyclic water/bacterial solution filtration tests, the modified membrane showed clear improvement in overall performances. Hence, for the virgin membrane, the initial water permeability, flux recovery ratio after the first cycle and flux recovery ratio after the second cycle were found to be 3000 L m−2 h−1.bar−1, 12 % and 53 %, respectively. For the optimized zwitterionic membrane, they were measured to be 7000 L m−2 h−1.bar−1, 26 % and 100 %, respectively. The efficacy of styrene maleic anhydride as a precursor for achieving stable and efficient zwitterionization of PVDF microfiltration membranes is evidenced, rendering it valuable for the filtration of microorganism-containing wastewater. Moreover, its potential application extends to the biomedical realm.

Efficient DNA separation and purification via VIPS-constructed membrane adsorbers

Solid phase extraction is an effective method for the separation and purification of nucleic acid molecules, which still suffers from high loss and low efficiency. Herein, a polyether sulfone membrane adsorber for deoxyribonucleic acid (DNA) separation and purification is constructed by combining vapor-induced phase separation (VIPS) technique and in-situ coupling reaction. More specifically, the slow phase separation during VIPS promotes the formation of reaction platform with loose bicontinuous structure, high porosity and surface segregation of poly (acrylic acid), which is subsequently highly aminated by in-situ coupling of polyethyleneimine. Significantly, the reversible binding of amine ligands to DNA is solely based on electrostatic interaction, which is regulated by medium pH, avoiding the requirement for additional binding agents as encountered by commercial silica matrices and dramatically reducing DNA loss. Consequently, the resulting membrane adsorber exhibits excellent DNA binding capacity of 293.3 mg·g−1 and improved dynamic DNA recovery efficiency of 85.2 %, far exceeding that of commercial silica matrices (55.5 %). This work provides a major breakthrough in the field of nucleic acid separation and purification, paving the way to construct next-generation solid phase extraction materials for biomacromolecules.

A switchable dual-mode film with designed intercalated and hierarchical structures for highly efficient passive radiation cooling and solar heating

A single-mode solar heating (SH) and passive radiative cooling (PRC) have been fast developed in outdoor thermal management. However, they hardly change with the temperature fluctuations of the hot and cold seasons. Herein, a flexible and stable dual-mode film with photo responsibility was engineered by integrating heating coating and cooling coating on the opposite surfaces of a porous polypropylene (PP) membrane. Flip the surfaces of the dual-mode film-facing solar light to switch between PRC and SH. The cross-linked heating side was fabricated from reduced graphene oxide (rGO) nanosheets intercalated with carbon black (CB) particles via spraying. A thick intercalated film can enhance solar absorptivity (96.4 %) and low infrared emissivity (8.0 %) due to the multiple solar reflections and adsorption between the interlayers, leading to high solar heating. The cooling side was derived from polyvinylidene fluoride (PVDF) coating embedded micro-nano Al2O3 particles via water vapor-induced phase separation (VIPS). The hierarchical coating with a pore size of 8.4 ± 0.1 µm and roughness of 4.0 ± 0.3 µm exhibits high solar reflectivity (92.2 %) and infrared emissivity (96.9 %), resulting in excellent passive radiative cooling. The net heating power (Pheating) and net cooling power (Pcooling) of the dual-mode film are 845.9 and 96.7 W m−2. Moreover, the dual-mode film exhibits outdoor thermoregulation capacity upon covering buildings, cars, and ice. In outdoor environments under solar radiation of 611 ∼ 716 W m−2, it has a temperature increase/decrease of 17.8/5.3 °C to the ambient temperature. Owing to the scalable fabrication processes and excellent thermoregulation characteristics, the dual-mode film is promising for applications in personal thermal management, energy-efficient buildings, in-car temperature control, and food freezing-thawing.

Recyclable and leakage-suppressed microcellular liquid–metal composite foams for stretchable electromagnetic shielding

The metallic conductivity and high liquidity of liquid metal (LM) make LM-polymer composites exhibit high electrical conductivity, large stretchability, and excellent mechanical–electrical decoupling, which provide significant advantages in the fabrication of stretchable electromagnetic interference (EMI) shielding materials. However, problems such as undesired LM leakage, high density, and poor recyclability due to the frequent use of chemically cross-linked polymers limit the applications of LM-polymer composites. Herein, we report the fabrication of stretchable and recyclable microcellular thermoplastic polyurethane (TPU)/LM composite foams (TLFs) with controllable LM distribution through a water–vapor-induced phase separation (WVIPS) process. The sedimentation of LM droplets helps to improve the shielding effectiveness (SE) of TLF, while the microcellular structure enables TLF with more uniform LM dispersion to achieve high leakage resistance. Moreover, the stretch-activated TLF shows high electrical stability with only slight resistance changes during stretching and exhibits a strain-insensitive shielding behavior. As a stretchable joule heater, the sample has outstanding Joule-heating performance, with stable temperature dropping only slightly under large tensile strains. More importantly, the excellent solubility of TPU, combined with a solution-based WVIPS process, allows our TLFs to be easily recycled into new products with very similar structure and performance to those before recycling, indicating the ideal recyclability of such materials.

Towards Single-Polymer-Based Fully Printed Textile-Based Flexible Ag2O-Zn Battery for Wearable Electronics

Printed textile-based flexible batteries are gaining attention in several applications, but they are becoming more relevant to the health care industry in terms of realizing wearable and skin-conformable electronic devices. A flexible battery must ideally be deformable along multiple directions. In this work, with an aim to develop a fully printed omnidirectional deformable battery, we report the fabrication process of a novel single-polymer-based flexible non-rechargeable planar Ag2O-Zn battery on a textile substrate using the stencil printing method. Except for the electrolyte, all the components of the battery, including the current collectors, the anode, the cathode, and the separator membrane, are fabricated using a single polymer, namely styrene–ethylene–butylene–styrene (SEBS). To fabricate the SEBS separator, we introduce the solvent evaporation-induced phase separation (SEIPS) process. In the SEIPS method, toluene and dimethyl sulfoxide (DMSO) are selected as the solvent–nonsolvent pair. The SEBS: toluene: DMSO system with a wt% ratio of 6:85:9 showed improved performance regarding the OCV tests. A polyacrylic acid (PAA)-based alkaline polymer gel is used as an electrolyte. The demonstrated process is simple, and, with suitable modifications, it should find its use in the development of digitally printed alkaline batteries.

Preparation and modification of PVDF membrane via VIPS method for membrane distillation

Membrane distillation (MD) is a promising technology for treating high-salinity mine water. However, MD membranes are known to have low membrane flux and are prone to fouling. In this study, we used the cost-effective and controllable vapor-induced phase separation (VIPS) technology to prepare polyvinylidene difluoride (PVDF) membranes, replacing the traditional immersion precipitation method and optimizing the membrane structure by including LiCl and acetone as porogen in the casting solution. The results showed that the membrane prepared using the VIPS method exhibited a highly open interconnected porous surface. Unlike traditional MD membranes with a dense epidermal layer and large finger-like pores, these optimized membranes had a symmetrical and uniform internal structure, leading to a high flux of 8.62 kg·(m2·h)−1 during direct contact membrane distillation testing. Different porogens produced varied results on the VIPS process and varying effects on membrane structure. The use of LiCl promoted the formation of PVDF β-phase, resulting in a decrease in the number of spherical nodules on the membrane surface, as well as improved density and smoothness. Consequently, this reduced fouling risk during membrane distillation while slightly decreasing membrane flux. On the other hand, acetone rapidly evaporated during the VIPS process, facilitating pre-gelatinization and α-phase formation of PVDF. This concurrent effect effectively restricted excessive nodule growth on the membrane surface, endowing the membrane with antifouling capabilities while preserving high flux.

Rapid attainment of full wettability through surface PEGylation of hydrophobic polyvinylidene fluoride membranes via spray-coating for enhanced anti-biofouling performances

This manuscript explores the development of antifouling membranes fabricated by vapor-induced phase separation (VIPS) process and their spray-coating modification with an aqueous solution of a copolymer comprising butyl methacrylate and poly(ethylene glycol) methyl ether methacrylate, designated as poly(BMA-r-PEGMA). An initial optimization phase focused on improving the modification quality, with the aim of enhancing the wettability on both the top and bottom surfaces of the membranes, despite spraying on the top surface only. Our findings reveal that a sprayed solution concentration of 10 mg/mL, a pressure of 0.25 MPa, and a scan rate of 3000 mm/min achieved a decrease in water contact angle to 0 in less than 12 s for both membrane surfaces (the top surface directly exposed to the spray, and the bottom surface facing the instrument stage), suggesting that the spray-coating modifies the entire membrane’s bulk. The presence of the copolymer on both surfaces was also evidenced by FTIR and XPS tests. Further biofouling assessments demonstrated the performances of the optimized membrane (OM). In static attachment tests, the OM exhibited a high reduction in Escherichia coli adhesion, with less than 10 % adhering bacteria, compared to unmodified membranes. During the filtration of bacteria-containing wastewater, the OM boasted a flux recovery ratio approaching 60 % (against less than 40 % for a commercial hydrophilic membrane), a rejection rate of 99.3 %, and a water permeability of 2500 LMH/bar. Moreover, the OM was stable over a 4-week period, with a resistance to E. coli attachment remaining similar to prior immersion. These findings underscore the significant potential of spray-coating to develop stable and effective antifouling microfiltration membranes for the removal of microorganisms from wastewater.