Search Results (411)

This study explores using polyvinylidene fluoride (PVDF) membranes modified with multi-walled carbon nanotubes (MWCNTs) to treat simulated and industrial brine from coal power stations. The MWCNTs were acid-treated and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Raman, and nitrogen sorption at 77 K, Thermogravimetric analysis (TGA), and Transmission electron microscopy (TEM). The desired membranes were obtained by casting from a solution of N-Methyl-2-pyrrolidone, PVDF, various weight percentages of MWCNTs, and a small amount of polyvinylpyrrolidone. The acid treatment of the MWCNTs introduced oxygen moieties on the surface, and increased pore volume and surface area while maintaining crystallinity and structural integrity remain preserved. The maximum rejection rate achieved was 41.82% with 1 wt.% of acid-treated MWCNTs in the PVDF membrane. Acid-treated MWCNTs loaded membranes had an improved rejection rate, which was 5× higher than membranes without MWCNTs. Full article

Planar heaters are designed to deliver uniform heat across broad surfaces and serve as critical components in applications requiring energy efficiency, safety, and mechanical flexibility, such as wearable electronics and smart textiles. However, conventional metal-based heaters are limited by poor adaptability to curved or complex surfaces, low mechanical compliance, and susceptibility to oxidation-induced degradation. To overcome these challenges, we applied a protein-assisted electroless copper (Cu) plating strategy to electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber substrates to fabricate flexible, conductive planar heating membranes. For interfacial functionalization, a protein-based engineering approach using bovine serum albumin (BSA) was employed to facilitate palladium ion coordination and seed formation. The resulting membrane exhibited a dense, continuous Cu coating, low sheet resistance, excellent durability under mechanical deformation, and stable heating performance at low voltages. These results demonstrate that the BSA-assisted strategy can be effectively extended to complex three-dimensional fibrous membranes, supporting its scalability and practical potential for next-generation conformal and wearable planar heaters. Full article

Background/Objectives: Airborne viral diseases pose a health risk, due to which there is a growing interest in developing filter materials capable of capturing fine particles containing virions from the air and that also have a virucidal effect. Nanofiber membranes made of poly(vinylidene fluoride) dissolved in N,N-dimethylacetamide and functionalized with copper, silver, and zinc nanoclusters were fabricated via electrospinning. This study aims to evaluate and compare the virucidal effects of nanofibers functionalized with metal nanoclusters against the human influenza A virus A/WSN/1933 (H1N1) and SARS-CoV-2. Methods: A comprehensive characterization of materials, including X-ray diffraction, scanning electron microscopy, microwave plasma atomic emission spectroscopy, thermogravimetric analysis, contact angle measurements, nitrogen sorption analysis, mercury intrusion porosimetry, filtration efficiency, and virucidal tests, was used to understand the interdependence of the materials’ physical characteristics and biological effects, as well as to determine their suitability for application as antiviral materials in air filtration systems. Results: All the filter materials tested demonstrated very high particle filtration efficiency (≥98.0%). The material embedded with copper nanoclusters showed strong virucidal efficacy against the SARS-CoV-2 alpha variant, achieving an approximately 1000-fold reduction in infectious virions within 12 h. The fibrous nanowire polymer functionalized with zinc nanoclusters was the most effective material against the human influenza A virus strain A/WSN/1933 (H1N1). Conclusions: The materials with Cu nanoclusters can be used with high efficiency to passivate and kill the SARS-CoV-2 alpha variant virions, and Zn nanoclusters modified activated porous membranes for killing human influenza A virus A7WSN/1933 (H1N1) virions. Full article

Fibrous structure is a promising building block for developing high-performance wearable piezoresistive sensors. However, the inherent non-conductivity of the fibrous polymer remains a bottleneck for highly sensitive and fast-responsive piezoresistive sensors. Herein, we reported a polyaniline/reduced graphene oxide @ polydopamine/poly (vinylidene fluoride) (PANI/rGO@PDA/PVDF) nanofiber piezoresistive sensor (PNPS) capable of versatile wearable biomonitoring. The PNPS was fabricated by integrating rGO sheets and PANI particles into a PDA-modified PVDF nanofiber network, where PDA was implemented to boost the interaction between the nanofiber networks and functional materials, PANI particles were deposited on a nanofiber substrate to construct electroactive nanofibers, and rGO sheets were utilized to interconnect nanofibers to strengthen in-plane charge carrier transport. Benefitting from the synergistic effect of multi-dimensional electroactive materials in piezoresistive membranes, the as-fabricated PNPS exhibits a high sensitivity of 13.43 kPa⁻¹ and a fast response time of 9 ms, which are significantly superior to those without an rGO sheet. Additionally, a wide pressure detection range from 0 to 30 kPa and great mechanical reliability over 12,000 cycles were attained. Furthermore, the as-prepared PNPS demonstrated the capability to detect radial arterial pulses, subtle limb motions, and diverse respiratory patterns, highlighting its potential for wearable biomonitoring and healthcare assessment. Full article

To improve solid-state lithium batteries, solution casting has been employed to create lithium ion-conducting copolymer electrolytes involving poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/polyvinylpyrrolidone (PVP) blend polymers with various compositions. Following X-ray diffraction and Fourier transformation (FTIR), the structural characterisation and identification of molecular bonding in polymer electrolytes were confirmed. Through AC impedance analysis, the electrical characteristics of the solid-state polymer films were investigated. The dielectric conductivity of the sample was found to obey the modified Arrhenius relationship, while in the case of a sample with higher conductivity, it followed Arrhenius behaviour. The relaxation parameters and dielectric behaviour of the samples are demonstrated and discussed. Full article

Poly(vinylidene fluoride-trifluoroethylene) (PVTF) nanoparticles coatings with electrically heterogeneous microdomains were engineered to mimic the natural electromechanical microenvironment of bone tissue, offering a novel strategy to enhance osteogenesis. Through a biphasic solvent phase separation method, PVTF nanoparticles (NPs) were synthesized and spin-coated onto substrates, followed by melt-recrystallization to achieve high β-phase crystallinity. The substrates were then subjected to corona poling, a process involving high-voltage corona discharge to electrically polarize and align the molecular dipoles. Structural and electrical characterization revealed tunable microdomain surface potentials and piezoelectric coefficients, correlating with enhanced hydrophilicity. Notably, microdomain potential—produced by controlled polarization—was shown to directly regulate cellular responses. In vitro studies demonstrated that a corona-poled PVTF NP coating significantly improved bone marrow mesenchymal stem cell (BMSC) proliferation and early osteogenic differentiation. This work establishes a surface electropatterning approach and highlights the critical role of electrical heterogeneity in bone regeneration, offering a novel strategy for bioactive biomaterial design. Full article

Lithium-ion batteries are restricted in development due to safety issues such as poor chemical stability and flammability of organic liquid electrolytes. Replacing liquid electrolytes with solid ones is crucial for improving battery safety and performance. This study aims to enhance the performance of polyethylene oxide (PEO)-based polymer via blending with poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)). The experimental results showed that the addition of P(VDF-HFP) disrupted the crystalline regions of PEO by increasing the amorphous domains, thus improving lithium-ion migration capability. The electrolyte membrane with 30 wt% P(VDF-HFP) and 70 wt% PEO exhibited the highest ionic conductivity, widest electrochemical window, and enhanced thermal stability, as well as a high lithium-ion transference number (0.45). The cells assembled with this membrane electrolyte demonstrated an excellent rate of performance and cycling stability, retaining specific capacities of 122.39 mAh g⁻¹ after 200 cycles at 0.5C, and 112.77 mAh g⁻¹ after 200 cycles at 1C and 25 °C. The full cell assembled with LiFePO₄ as the positive electrode exhibits excellent rate performance and good cycling stability, indicating that prepared solid electrolytes have great potential applications in lithium batteries. Full article

Gel electrolytes (GEs) play a pivotal role in the advancement of lithium metal batteries by offering high energy density and enhanced rate capability. Nevertheless, their real-world application is hampered by relatively low ionic conductivity and significant interfacial resistance at room temperatures. In this work, we developed a gel electrolyte membrane (GEM) by embedding Zeolitic Imidazolate Framework-8 (ZIF-8) metal–organic frameworks (MOFs) material into a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix through UV curing. The composite membrane, with 4 wt% ZIF-8, exhibited an ionic conductivity of 1.17 × 10⁻³ S/cm, an electrochemical stability window of 4.7 V, and a lithium-ion transference number of 0.7. The test results indicate that the electrochemical performance of LFP//GEM//Li battery has an initial specific capacity of 168 mAh g⁻¹ at 0.1 C rate. At 1 C, the discharge capacity was 88 mAh g⁻¹, and at 2 C, it was 68 mAh g⁻¹. Enhanced ionic transport, improved electrochemical stability, and optimized lithium-ion migration collectively contributed to superior rate performance and prolonged cycle life. This study offers novel insights and methodological advances for next-generation lithium metal batteries technologies. Full article

Multi-scale characterization techniques have been employed to analyze the size effect of microstructure on the phase transition behavior and dielectric properties of poly(vinylidene fluoride) (PVDF) films. The results show that oriented amorphous fraction layers are prone to form in the vicinity of the grain boundaries of nano-grained films, while the interfacial polarization and electrostriction effect play a major role. Polar nano-regions are prone to form in micro-grained films, and the maximum fraction of polar crystalline phase and maximal dielectric constant can be achieved due to the balance between the intrinsic effect and extrinsic effect of the material. On the contrary, the extrinsic effect corresponding to interfacial charges greatly influences the phase transition behavior between beta and alpha phases for coarse-grained PVDF films, while the dielectric properties are mainly influenced by the intrinsic electrostatic field and van der Waal interaction of the material. Hence, the dielectric behavior of nano-grained films can be adjusted by the copolymerization technique, that of micro-grained films can be adjusted by both the copolymerization technique and the controlling of microstructure morphology, and that of coarse-grained films can be adjusted by the doping technique. Full article

Ultrafiltration is essential for wastewater treatment, but it faces challenges such as selectivity, control, and fouling reduction. Incorporating nanoparticles into membranes enhances retention, boosts permeability, and limits fouling, improving overall performance. This study explores the properties of PVDF/Ag-ZnO composite membranes, highlighting the influence of silver-doped zinc oxide nanoparticles on membrane structure, performance, and antimicrobial effect. The non-solvent-induced phase separation (NIPS) method successfully led to the preparation of composite membranes; this method used different doses of silver-doped zinc oxide (Ag-ZnO) nanoparticles with Poly(vinylidene fluoride) (PVDF). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements were used to validate the influence of nanoparticles on the composite membrane (PVDF/Ag-ZnO) structure. Conversely, morphology (porosity, surface rigorosity), hydrophilicity, and permeability were analyzed through contact angle, image analysis, and flux measurement. In addition, the membranes were tested for antimicrobial activity against E. coli. Membrane performance shows that the incorporation of 20% w/w Ag-ZnO resulted in improved water permeability, which was about 2.73 times higher than that of a pure PVDF membrane (192.2 L·m⁻²·h⁻¹·bar⁻¹). The membrane porosity showed a linear increase with the number of NPs. The resultant asymmetric membrane was altered to increase the number of pores on the top surface by 61% and the cross-sectional pore surface by 663%. Furthermore, a high antibacterial activity of Ag-ZnO 20% was shown. Full article

Solid-state electrolytes are widely expected to enhance the performance of lithium-ion batteries, providing higher energy density and improved safety. However, challenges still need to be solved in their practical application due to low ionic conductivity and high interfacial resistance at room temperature. In this study, we successfully developed a high-performance gel polymer electrolyte (GPEs) by blending poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) and polyacrylonitrile (PAN) through UV curing, cross-linking with ethoxylated trimethylolpropane triacrylate (ETPTA), and incorporating Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO). At room temperature, the ionic conductivity of the GPEs was 2.8 × 10⁻⁴ S/cm, with a lithium-ion transference number of 0.6. Moreover, during lithium plating/stripping tests, the assembled Li/PPEL/Li symmetric cell exhibited stable cycling for up to 600 h at a current density of 0.1 mA/cm². Notably, the GPEs enabled the LiFePO₄/GPEs/Li battery to achieve excellent performance, delivering high discharge capacities at room temperature (164.3 mAh g⁻¹ at 0.1 C and 88.8 mAh g⁻¹ at 1 C), with a capacity retention of 89.4% after 200 cycles at 0.5 C. Therefore, solid-state batteries using this electrolyte exhibit excellent performance, including adequate capacity and cycling stability. Full article

Gel polymer electrolyte (GPE) with a polymer matrix swollen in liquid electrolytes offers several advantages over conventional liquid electrolytes, including no leakage, lightweight properties, and high reliability. While poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based GPEs show promise for lithium-ion batteries, their practical application is hindered by the intrinsic trade-off between ionic conductivity and mechanical robustness in conventional PVDF systems. Typical strategies relying on excessive plasticizers (e.g., ionic liquids) compromise mechanical integrity. Here, we propose a novel hot-pressing-induced recrystallization strategy to synergistically enhance both anisotropic ionic conductivity and puncture strength in PVDF-based GPE films. By blending PVDF with controlled amounts of 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl), followed by solution casting and hot pressing, we achieve microstructural reorganization that dramatically improves through-thickness ion transport and mechanical performance. Crucially, hot-pressed PVDF with only 25 wt% [HMIM]Cl exhibits a 12.5-fold increase in ionic conductivity (reaching 4.7 × 10⁻⁴ S/cm) compared to its solution-cast counterparts. Remarkably, this formulation surpasses the conductivity of PVDF-HFP composites with a higher [HMIM]Cl content (35 wt%, 1.7 × 10⁻⁴ S/cm), demonstrating performance optimization of anisotropic conductivity. What is more, the mechanical strength of the piercing strength perpendicular to the GPE film after hot pressing increased by 42% compared to the solution-cast film. This work establishes a scalable processing route to break the conductivity–strength dichotomy in GPEs, offering critical insights for designing high-performance polymer electrolytes. Full article

Long-time exposure to volatile organic compounds (VOCs) in the atmosphere can have negative health effects on humans and other living organisms. In order to purify ambient air, these VOCs can be degraded using photocatalysis. In this research, commercially available TiO₂ nanoparticles were immobilized in a porous poly(vinylidene fluoride-co-hexa-fluoropropylene) (PVDF) polymer matrix, synthesized using the phase inversion method. The most used solvent for PVDF is N-methyl-2-pyrrolidone (NMP). However, this solvent is known to be harmful to humans and the environment, and there is a need to replace NMP with a more ecological ‘green’ solvent. Here, triethyl phosphate (TEP), methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (Rhodiasolv^® PolarClean) and propylene carbonate (PC) were used to dissolve PVDF for the phase inversion synthesis of porous photocatalytically active PVDF/TiO₂ hybrid layers onto aluminium slides. The photocatalytic degradation under UV (365 nm) of gaseous ethanol in an argon/oxygen (Ar/O₂) atmosphere shows that these solvents are suitable replacements for NMP, but optimization is required to improve the performance of the layers. Apart from changing the solvent for PVDF, the UV and photocatalysis stability of PVDF has been determined, as well as the repeatability of the photocatalytic reaction, to prove that PVDF is a suitable polymer for this application. Full article

This study explores the influence of various additives on the morphological, chemical, and thermal properties of poly(vinylidene fluoride) (PVDF) membranes prepared via the non-solvent induced phase separation (NIPS) technique. The use of a green solvent such as triethyl phosphate (TEP) was shown to be successful. A particular focus was dedicated to pore formers based on choline chloride–based deep eutectic solvents (DES) in combination with ethylene glycol and glycerol, i.e., ChCl/EG and ChCl/GLY, and its benchmark with traditional counterparts such as poly(ethylene glycol) (PEG) and glycerol (GLY). Comprehensive characterization was conducted using FESEM, FTIR, XRD, and DSC techniques to evaluate changes in membrane morphology, porosity, and crystallinity. PEG acted as a pore-forming agent, transitioning the internal structure from spherulitic to sponge-like with consistent pore sizes, while GLY produced a nodular morphology at higher concentrations due to increased dope solution viscosity. DES induced significant shifts in crystalline phase composition, decreasing α-phase fractions and promoting β-phase formation at higher concentrations. While the overall porosity remained unaffected by the addition of GLY or PEG, it was dependent on the DES concentration in the dope at lower values than those obtained by GLY and PEG. Membrane pore size with ChCl/GLY was lower than with ChCl/EG and GLY. All membranes showed performance at the hydrophobic regime. The findings demonstrate that ChCl/EG and ChCl/GLY can tailor the structural and thermal properties of TEP-driven PVDF membranes, providing a green and versatile approach to customize the membrane properties for specific applications. Full article

Bone tissue is intrinsically electroactive, and electrical signaling is one of its key regulatory mechanisms. The electroactive poly (vinylidene fluoride trifluoroethylene) (PVTF), due to its piezoelectricity, can provide electrical stimulation to cells, regulating their proliferation and osteogenic differentiation. Collagen I (COL) is the main organic component of bone and is involved in various physiological processes of bone. A crucial question that remains to be explored is whether electroactive materials can meet the requirements for GBR membranes and what synergistic effects electrical signals and collagen’s biochemical signals might have on cellular behavior. In this study, PVTF/COL composite films were prepared using polydopamine (PDA). It was found that collagen modification could increase the surface Kelvin potential of PVTF from −5.07 V to 2.22 V, reduce the WCA from 98.9° to 33.2°, and maintain the tensile strength of PVTF at 24.94 MPa. Additionally, the composite film significantly promoted the adhesion and proliferation of bone marrow stem cells (BMSCs), and the ALP activity on PPC3 films after 7 days was 5.6 times higher than that on P films. This study presents a novel and effective approach for surface modification of PVTF and explores its potential applications in GBR. Full article