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Radiative cooling is promising in meeting the current global demand for green sustainable development. However, the effective cooling of the existing radiant cooler will be limited due to the serious solar energy absorption and poor thermal insulation performance on the cold side. To addresss these issues, we propose herein a novel composite material of silicon dioxide (SiO 2) aerogel microspheres combined with polyvinylidene fluoride-cohexafluoropropylene (PVDF-HFP) nanofiber membrane, in which SiO 2 aerogel microspheres are firstly synthesized by sol-gel method and then incorporated into PVDF-HFP nanofiber membrane to give radiative cooling performance. As we expected, the molecular vibration characteristics of PVDF-HFP nanofiber membrane and the phonon polarization resonance of Si-O-Si bond in the transparent window can enhance the infrared emissivity of the membrane surface. In addition, the high porosity and the mesoporous structure formed by the interconnection of nano-network skeletons of SiO 2 aerogel microspheres determine its excellent thermal insulation performance. The as-prepared material displays that the average solar reflectance of the composite membrane is 96.07 % and the average infrared emissivity of the atmospheric window is 94.95 %. Notably, when the average solar radiation intensity is 885.56 W•m−2, the passive radiative cooling temperature during the day can reach 11.2 °C. Furthermore, this material has excellent self-cleaning and thermal insulation performance, making it a potential radiant cooling candidate in many fields. [ABSTRACT FROM AUTHOR]

Barium titanate doped with calcium and zirconium (BCZT) relaxor ferroelectric ceramics enhance energy storage capabilities due to their excellent ferroelectric and dielectric properties. In this investigation, BCZT particles (Ps) were incorporated into poly (vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) using the solvent casting method to prepare biocompatible composite films with varying BCZT Ps contents. The uniform dispersion and distribution of BCZT Ps throughout the polymer matrix results in robust interfacial interactions, promoting improved nucleation of the β-phase in PVDF-HFP and increased thermal stability with higher BCZT Ps loading. The Young's modulus and tensile strength of the composites experienced respective increases of 78.2 % and 41.8 % with the addition of 20 wt% BCZT Ps. While the dielectric constant was improved from 12 to 31. This research contributes to the development of flexible composite films with different BCZT Ps contents, to promote an innovative and environmentally friendly energy harvesting technology. This innovation captures environmental vibrations and converts them into electrical energy to supply a variety of sensors. [ABSTRACT FROM AUTHOR]

Energy storage devices play a crucial role in all kinds of electronic devices. Rechargeable lithium-ion batteries have run across problems such as energy density, toughness, and safety. In order to conquer these hindrances, in this work, a novel solid-state polymer electrolyte for lithium-ion batteries was synthesized by blending polymethyl methacrylate (PMMA) in poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) with constant weight percent of ethylene carbonate (EC) and lithium bis (trifluoro methane sulfonyl) imide (LiTFSI), and different concentrations of calcium oxide (CaO). The composite polymer electrolytes (CPEs) (PVdF-HFP:PMMA:LiTFSI:EC:CaO) were fabricated using the solution casting technique. Powder XRD reveals enhancement in intensity with increasing CaO content. FTIR shows the interaction between the polymer-salt matrix. Among the analyzed films, PVdF-HFP:PMMA:LiTFSI:EC:CaO (10 wt.%) exhibits high ionic conductivity (10–4 S/cm) and good electrochemical (4 V) and thermal stability (350℃) which makes it suitable for solid-state electrolyte as a separator in energy storage applications. [ABSTRACT FROM AUTHOR]

A salient bottleneck to driving the wider use of polyvinylidene fluoride (PVDF) and its copolymers in smart applications is the requirement for a high-voltage poling process required to activate their $\beta $β-phase crystal structure before the realisation of the piezoelectricity response. In pursuit of enhancing the β-phase content of PVDF-based films, various approaches have been employed in recent years. Yet, a perfect solution to the challenge remains elusive. Here, we report a preliminary investigation into the production of unpoled poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) films reinforced with barium titanate (BaTiO3) and activated carbon (AC) to improve the piezoelectric property. Employing the mixture design of experiments (MDOE) method, various formulations of the composite’s constituents weight fractions were determined. Afterwards, series of composite films were produced via a toxic-free solution casting method and characterised by Fourier Transform Infrared Spectrum (FTIR) to determine the β-phase content. A non-linear polynomial regression model was established from the experimental FTIR data, and the adequacy of the model was confirmed using ANOVA. Subsequently, an MDOE-enabled optimisation was undertaken, generating a formulation of the composite to obtain the highest β-phase content to be $15$15 wt.% BaTiO3 and $0.74$0.74 wt.% AC. This combination produces a theoretically predicted β-phase content of $72.7$72.7%. A further experimental test employing the optimal formulation produced a β-phase content of $71.90$71.90%, achieved with neither mechanical stretching, thermal annealing, nor electrical poling. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multifunctional supramolecular polymer (MSP) cross-linked with the PVDF-HFP gel electrolyte. • The composite gel electrolyte (PH-10%MSP-GE) shows enhanced hardness and ionic conductivity. • The PH-10%MSP-GE demonstrates good interfacial adaptability with Li metal electrodes. • The Li|PH-10%MSP-GE|LiFePO 4 cell exhibits excellent electrochemical performance. Lithium (Li) metal batteries have the advantage of high energy density, but the Li dendrites risk piercing the separator and causing a short circuit in the battery. Replacing the liquid electrolytes with gel electrolytes is considered an effective strategy to solve the issues. Herein, a poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP)-based gel electrolyte, improved with multifunctional supramolecular polymer (MSP), was prepared to enhance the cycling stability and energy density of quasi-solid-state Li metal batteries. The MSP addictive constructs a cross-linked network structure with PVDF-HFP matrix and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) through hydrogen bonding, improving the mechanical strength of the composite gel electrolyte (PH-10%MSP-GE) to against the growth of Li dendrites. Moreover, the pre-lithiated sulfonic acid groups, conductive polyether groups of MSP, and the attraction of TFSI– anions, promote the Li-ion transportation of the composite gel electrolyte. Finally, the Li||Li symmetric cell cycle stably for over 450 h. The Li||LiFePO 4 full cell demonstrates a high energy density and excellent cycling stability for over 600 cycles, with a capacity retention rate of up to 98.7%. This work provides valuable insights into the preparation of multifunctional composite gel polymer electrolytes and competitive quasi-solid-state Li metal batteries. [ABSTRACT FROM AUTHOR]

A simple solution casting technique was used to formulate films of polyvinylidenefluoride‐co‐hexafluoropropylene, polymethylmethacrylate, and Ti3AlC2 MAX phase polymer nanocomposites (PPT) with different filler content. The functional groups present in the PPT films were studied using the Fourier transform infrared spectroscopy and the nature of crystallinity was observed using X‐ray diffraction technique. The morphology of the films was studied by scanning electron microscopy. The thermal analysis was done using the thermogravimetric analysis and differential thermogravimetry analysis. The tensile behavior of the prepared films was studied from the stress‐strain graphs. The ultraviolet–visible spectra revealed their optical characteristics. The dielectric parameters of the polymer blend and nanocomposite films like dielectric constant, loss tangent, AC conductivity, and complex impedance spectroscopy with corresponding equivalent circuits were studied. A comparative study of the above parameters was done for both the polymer blend and nanocomposites to find out the advancement in the properties of the prepared nanocomposite compared with the polymer blend. The nanocomposite film having 3 wt% of Ti3AlC2 MAX phase filler loading exhibited the best properties among all the nanocomposites. The enhanced dielectric properties of the nanocomposites with mechanical and thermal resistance can be used for real‐time efficient energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary composite membranes have been developed for battery separator applications. • Membranes have been developed by varying silver nanowires and titanium dioxide nanoparticle content. • Ternary composites show improved mechanical and electrochemical responses. • An ionic conductivity > 10−4 S/cm has been obtained independently of the filler type and content. • The highest discharge capacity value has been obtained for the 5 wt% AgNWs/5 wt% TiO 2 /PVDF-HFP membranes. In the realm of polymer composites, there is growing interest in the use of more than one filler for achieving multifunctional properties. In this work, a composite separator membrane has been developed for lithium-ion battery application, by incorporating conductive silver nanowires (AgNWs) and titanium dioxide (TiO 2) nanoparticles into a poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) polymer matrix. The composite membranes were manufactured by solvent casting and thermally induced phase separation, with total filler content varying up to 10 wt%. The ternary composites composites present improved mechanical characteristics, ionic conductivity and lithium transfer number compared to the neat polymer matrix. On the other hand, the filler type and content within the composite has little bearing on the morphology, polymer phase, or thermal stability. Once applied as a separator in lithium-ion batteries, the highest discharge capacity value was obtained for the 5 wt% AgNWs/5 wt% TiO 2 /PVDF-HFP membrane at different C-rates, benefiting from the synergetic effect from both fillers. This work demonstrates that higher battery performance can be achieved for next-generation lithium-ion batteries by using separator membranes based on ternary composites. [ABSTRACT FROM AUTHOR]

The present study investigates the influence of photosensitizer selection and the polymer electrolyte composition on the performance of quasi-solid-state dye-sensitized solar cells (QsDSSCs). Two benchmark ruthenium dyes, N719 and Z907, alongside a novel photoactive phenothiazine dye were used. Each dye was incorporated into a QsDSSC architecture employing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the gel electrolyte matrix, with varying molecular weights, to investigate their impacts on the overall device performance and long-term stability. Our results demonstrated that the N719 dye exhibited the highest power conversion efficiency (PCE), attributed to its strong absorption in the visible spectrum and efficient electron injection into the TiO2 photoanode. Z907, on the other hand, showed moderate PCE due to its broader absorption profile but slower electron injection kinetics. The phenothiazine dye revealed promising PCE, with tunable absorption properties and efficient charge transfer. Furthermore, the impact of PVDF-HFP polymer gel electrolytes with varying molecular weights on cell stability was explored. The QsDSSC incorporating the PVH80 polymer with the phenothiazine dye exhibited reduced dye desorption, due to the effective dye molecules' immobilization by the gel matrix, and consequently enhanced long-term stability over 600 h. This comparative study sheds light on the interplay between dye selection, the polymer gel's properties, and QsDSSCs' performance. These insights are crucial in designing robust and efficient QsDSSCs for practical applications. [ABSTRACT FROM AUTHOR]

Fouling and biofouling remain significant challenges in seawater desalination plants. One practical approach to address these issues is to develop anti-biofouling membranes. Therefore, novel hybrid zinc phthalocyanine/polyvinylidene fluoride-co-hexafluoropropylene (Zn(4-PPOx)4Pc/PVDF-HFP) membranes were prepared by electrospinning to evaluate their properties against biofouling. The hybrid nanofiber membrane was characterized by atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle measurements. The theoretical calculations of PVDF-HFP, Zn(4-PPOx)4Pc), and Zn(4-PPOx)4Pc/PVDF-HFP nanofibers were performed using a hybrid functional RB3LYP and the 6-31 G (d,p) basis set, employing Gaussian 09. DFT calculations illustrated that the calculated physical and electronic parameters ensured the feasibility of the interaction of PVDF-HFP with Zn(4-PPOx)4Pc via a halogen–hydrogen bond, resulting in a highly stable and remarkably reactive structure. Moreover, molecular electrostatic potential (MEP) maps were drawn to identify the reactive regions of the Zn(4-PPOx)4Pc and PVDF-HFP/Zn(4-PPOx)4Pc nanofibers. Molecular docking analysis revealed that Zn(4-PPOx)4Pc has highest binding affinity (−8.56 kcal/mol) with protein from S. aureus (1N67) mainly with ten amino acids (ASP405, LYS374, GLU446, ASN406, ALA441, TYR372, LYS371, TYR448, LYS374, and ALA442). These findings highlight the promising potential of Zn(4-PPOx) 4Pc/PVDF-HFP nanocomposite membranes in improving the efficiency of water desalination by reducing biofouling and providing antibacterial properties. [ABSTRACT FROM AUTHOR]

In today's technological landscape, advancing methods for producing conductive membranes that simplify and streamline the development of advanced interface materials is crucial. This study introduces a versatile and innovative method for fabricating superhydrophilic, conductive nanofibrous membranes based on the in situ synthesis of polypyrrole nanoparticles on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) electrospun fibers. The composite membranes morphologically exhibit a particle‐decorated nanofibrous configuration, with polypyrrole nanoparticles distributed along the individual fibers' surface. The nanoparticle‐nanofiber configuration shows distinctive properties; electrochemically, the electrospun mats demonstrate excellent inherent electrical conductivity, good cyclic and high electrochemical stability, and low resistance. Furthermore, the amphiphilic and superhydrophilic behavior, achieved through nanotopography, porosity and interactions between the intrinsically conductive polymer and the PVDF‐HFP fibers, enables efficient uptake of polar and nonpolar analytes. The membranes also demonstrate good in vitro cell viability of both murine and human fibroblasts. Given its efficient interaction with liquids and omnidirectional 360‐degree conductivity, this material emerges as an excellent candidate for use as a biocompatible, multifunctional interface layer. The produced nanoparticle‐nanofibrous membrane materials offer a promising platform for interface applications, featuring enhanced spatiotemporal configurations and wide‐ranging applicability. [ABSTRACT FROM AUTHOR]

Cellulose has advantages of easy availability, low price, renewability and biodegradability, making it a very promising substitute for fossil-based materials. A safe composite cellulose membrane for quasi-solid-state lithium ion batteries has been developed by coating cellulose separators with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and lithium aluminum titanium phosphate (LATP). This membrane exhibits excellent electrochemical performance, with an ionic conductivity as high as 2.1 mS cm−1, and a lithium-ion transference number of 0.57. The membrane shows good electrolyte wetting properties, with porosity and liquid electrolyte uptake of 47.2 % and 401.7 %, respectively. It has good thermal stability and can maintain its dimensional stability even at 200 ℃. The capacity retention of the quasi-solid-state LiFePO4/Li battery assembled with this membrane after 200 cycles at 0.2 C is about 86.7 %. The quasi-solid-state battery has good thermal stability and is not prone to thermal runaway.

Abstract This study is the first application of a PVDF-HFP-based polymer inclusion membrane incorporating the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and di(2-ethylhexyl)phosphoric acid (D2EHPA) as the base polymer and extractant for the extraction of bismuth(III), respectively. It is demonstrated that the PIM comprised of 60 wt% PVDF-HFP and 40 wt% D2EHPA is the most effective in the extraction of bismuth(III) from feed solution containing 20 mg L−1 bismuth(III) and 0.2 mol L−1 sulfate adjusted to pH 1.4. The extracted bismuth(III) ions are back-extracted quantitatively to the receiving solution containing 1 mol L−1 sulfuric acid. The stoichiometry experiments reveal that the Bi: D2EHPA ratio in the bismuth(III) extracted complex is 1:6, and D2EHPA is dimer. Moreover, it is shown that the studied PIM has high selectivity in the extraction of bismuth(III) over other interfering ions such as Mo(VI), Cr(III), Al(III), Fe(III), Ni(II), Zn(II), Cd(II), Co(II), Cu(II), and Mn(II). The interference of Fe(III) is also eliminated by masking with fluoride, leading finally to a nearly pure extraction of bismuth(III).

High piezoelectric composite films composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ferromagnetic cobalt ferrite (CoFe2O4) (0.00 ​wt% to 0.2 ​wt%) are prepared by a solution casting method accompanied by uniaxial stretching and high electric field poling. The decisive effect of the poling electric field on the power generating capability was confirmed by the experiments. For pure PVDF-HFP films, when the maximum electric field Emax is 120 ​MV/m, the calibrated open circuit voltage reaches 2.93 ​V, which is much higher than those poled at lower electric fields (70 ​MV/m: 1.41 ​V; 90 ​MV/m: 2.11 ​V). Furthermore, the addition of CoFe2O4 also influences the piezoelectricity dramatically. In the samples containing 0.15 ​wt% CoFe2O4, the calibrated open circuit voltage increases to the maximum value of 3.57 ​V. Meanwhile, the relative fraction of the β-phase and the crystallinity degree are 99% and 48%, respectively. The effects of CoFe2O4 nanoparticles on initial crystallization, uniaxial stretching and high electric field poling are investigated by XRD, FTIR and DSC.

This study is the first application of a PVDF-HFP-based polymer inclusion membrane incorporating the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and di(2-ethylhexyl)phosphoric acid (D2EHPA) as the base polymer and extractant for the extraction of bismuth(III), respectively. It is demonstrated that the PIM comprised of 60 wt% PVDF-HFP and 40 wt% D2EHPA is the most effective in the extraction of bismuth(III) from feed solution containing 20 mg L−1 bismuth(III) and 0.2 mol L−1 sulfate adjusted to pH 1.4. The extracted bismuth(III) ions are back-extracted quantitatively to the receiving solution containing 1 mol L−1 sulfuric acid. The stoichiometry experiments reveal that the Bi: D2EHPA ratio in the bismuth(III) extracted complex is 1:6, and D2EHPA is dimer. Moreover, it is shown that the studied PIM has high selectivity in the extraction of bismuth(III) over other interfering ions such as Mo(VI), Cr(III), Al(III), Fe(III), Ni(II), Zn(II), Cd(II), Co(II), Cu(II), and Mn(II). The interference of Fe(III) is also eliminated by masking with fluoride, leading finally to a nearly pure extraction of bismuth(III). [ABSTRACT FROM AUTHOR]

For enhanced security in hardware‐based security devices, it is essential to extract various independent characteristics from a single device to generate multiple keys based on specific values. Additionally, the secure destruction of authentication information is crucial for the integrity of the data. Doped amorphous indium gallium zinc oxide (a‐IGZO) thin‐film transistors (TFTs) using poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) induce a dipole doping effect through a phase‐transition process, creating physically unclonable function (PUF) devices for secure user information protection. The PUF security key, generated at VGS = 20 V in a 20 × 10 grid, demonstrates uniformity of 42% and inter‐Hamming distance (inter‐HD) of 49.79% in the β‐phase of PVDF‐HFP. However, in the γ‐phase, the uniformity drops to 22.5%, and inter‐HD decreases to 35.74%, indicating potential security key destruction during the phase transition. To enhance security, a multi‐factor authentication (MFA) system is integrated, utilizing five security keys extracted from various TFT parameters. The security keys from turn‐on voltage (VON), VGS = 20 V, VGS = 30 V, mobility, and threshold voltage (Vth) exhibit near‐ideal uniformities and inter‐HDs, with the highest values of 58% and 51.68%, respectively. The dual security system, combining phase transition and MFA, establishes a robust protection mechanism for privacy‐sensitive user information. [ABSTRACT FROM AUTHOR]

In this paper, a high‐performance composite nanofiber membrane with excellent air filtration and dye degradation properties was prepared by incorporating MIL‐53(Fe) nanoparticles into the electrospinning solution. The results showed that the filtration efficiency for PM2.5 of the PP/PVDF‐HFP/MIL‐53(Fe) composite nanofiber membrane reached up to 99.3% with the addition of 2 wt% MIL‐53(Fe). Moreover, the composite nanofiber membrane exhibited steady filtration efficiency across different parameters, including air velocity, PM2.5 concentration, and extended testing time. Furthermore, the incorporation of MIL‐53(Fe) significantly enhanced the removal efficiency of the composite nanofiber membrane toward Rh B, resulting in a remarkable 91% removal rate. The polymer/MOF composite nanofiber membranes prepared by simple and cheap electrospinning technology have a wide range of practical applications in the field of environmental protection. Highlights: PPM composite nanofiber membrane was prepared via electrospinning method.MIL‐53(Fe) nanoparticles were introduced to PPM composite nanofiber membrane.PPM composite nanofiber membrane showed excellent removal efficiency for PM2.5.PPM composite nanofiber showed a good removal performance for RhB in solution. [ABSTRACT FROM AUTHOR]

Abstract In today's technological landscape, advancing methods for producing conductive membranes that simplify and streamline the development of advanced interface materials is crucial. This study introduces a versatile and innovative method for fabricating superhydrophilic, conductive nanofibrous membranes based on the in situ synthesis of polypyrrole nanoparticles on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) electrospun fibers. The composite membranes morphologically exhibit a particle‐decorated nanofibrous configuration, with polypyrrole nanoparticles distributed along the individual fibers' surface. The nanoparticle‐nanofiber configuration shows distinctive properties; electrochemically, the electrospun mats demonstrate excellent inherent electrical conductivity, good cyclic and high electrochemical stability, and low resistance. Furthermore, the amphiphilic and superhydrophilic behavior, achieved through nanotopography, porosity and interactions between the intrinsically conductive polymer and the PVDF‐HFP fibers, enables efficient uptake of polar and nonpolar analytes. The membranes also demonstrate good in vitro cell viability of both murine and human fibroblasts. Given its efficient interaction with liquids and omnidirectional 360‐degree conductivity, this material emerges as an excellent candidate for use as a biocompatible, multifunctional interface layer. The produced nanoparticle‐nanofibrous membrane materials offer a promising platform for interface applications, featuring enhanced spatiotemporal configurations and wide‐ranging applicability.

In this work, poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP)/mesoporous graphitic carbon nitride (mpg‐C3N4) composite fiber web have been prepared and characterized for photocatalytic methylene blue (MB) degradation and sensing applications. The electrospinning technique, operating at a flow rate of 1 mL/h and a voltage of 15 kV, was utilized to prepare the composite membranes of PVDF‐HFP with the uniform distribution of the mpg‐C3N4. The composite web demonstrated outstanding photocatalytic activity for the degradation of MB, reaching a quick 68% drop in MB concentration in just 45 min. The composite web furthermore worked as a sensor for MB detection. After MB exposure, the film resistance was increased, suggesting its potential as a chemiresistive sensor. The maximum resistivity of PVDF‐HFP/mpg‐C3N4 composites was found to be 90 Ω·m at 2% concentration of MB. The MB molecules' adsorption on the surface of the composite web and the existence of photocatalytic byproducts on the surface may be responsible for this shift in resistance. This dual functionality highlights the adaptability and potential of the PVDF‐HFP/mpg‐C3N4 composite web as a versatile material for environmental sensing and cleanup. This research presents a comprehensive approach to the synthesis, characterization, and evaluation of such flexible membranes for potential applications as self‐cleaning devices and chemiresistive sensor. Highlights: PVDF‐HFP/mpg‐C3N4 composite membranes act as an efficient material for MB degradation (68%) with visible light exposure.mpg‐C3N4 plays the role of active material in degradation.PVDF‐HFP/mpg‐C3N4 composite membrane also act as sensors for MB detection.Composite membrane becomes chemiresistive due to notable resistivity changes with MB concentration. [ABSTRACT FROM AUTHOR]

Piezoelectric ceramic and polymeric separators have been proposed to effectively regulate Li deposition and suppress dendrite growth, but such separators still fail to satisfactorily support durable operation of lithium metal batteries owing to the fragile ceramic layer or low‐piezoelectricity polymer as employed. Herein, by combining PVDF‐HFP and ferroelectric BaTiO3, we develop a homogeneous, single‐layer composite separator with strong piezoelectric effects to inhibit dendrite growth while maintaining high mechanical strength. As squeezed by local protrusion, the polarized PVDF‐HFP/BaTiO3 composite separator generates a local voltage to suppress the local‐intensified electric field and further deconcentrate regional lithium‐ion flux to retard lithium deposition on the protrusion, hence enabling a smoother and more compact lithium deposition morphology than the unpoled composite separator and the pure PVDF‐HFP separator, especially at high rates. Remarkably, the homogeneous incorporation of BaTiO3 highly improves the piezoelectric performances of the separator with residual polarization of 0.086 μC cm−2 after polarization treatment, four times that of the pure PVDF‐HFP separator, and simultaneously increases the transference number of lithium‐ion from 0.45 to 0.57. Beneficial from the prominent piezoelectric mechanism, the polarized PVDF‐HFP/BaTiO3 composite separator enables stable cyclic performances of Li||LiFePO4 cells for 400 cycles at 2 C (1 C = 170 mA g−1) with a capacity retention above 99%, and for 600 cycles at 5 C with a capacity retention over 85%. [ABSTRACT FROM AUTHOR]

Exploration of blend polymer membrane with desire performances is a highly essential research topic because it makes them as key component of the battery technologies. However, the blend membrane cannot simultaneously meet out the high electrical insulation and ion conductivity. Here, we report porous PVdF-HFP based polymer membrane blended with P123 polymer which is prepared by phase inversion technique and along with solution casting technique for comparison. Especially, the major improvements can be claimed with porous PVdF-HFP blend with P123 matrix by phase inversion process that could be mainly due to increasing the disorganize crystallinity of the PVdF-HFP, thereby enhancing the ionic conductivity of PVdF-HFP/P123 than the same prepared by traditional solution casting. More importantly, our studies reveals that, besides having an effect of crystallinity and high ionic conduction PVdF-HFP/P123 blend matrix yield homogeneous pores with higher pore density when prepared by phase inversion approach. We attribute this to remarkable enhancement in higher electrolyte uptake and higher cation transport in the blend membrane. This facilitates high ionic conductivity of 7.06 × 10−5 S/cm and electrochemical stability of 2.8 V,while the solution casting approach display low ionic conductivity of 1.63 × 10−6 S/cm and electrochemical stability of 2.2 V, respectively. A symmetric supercapacitor device is fabricated with the membrane prepared by phase inversion process, resulting in a high specific capacitance of 80 F/g at the current density of 0.25 A/g with 90.51% specific capacitance retention at 0.5 A/g. The energy density of 90.9 W/kg can be achieved at the power density of 0.375 W/kg.

The present study investigates the influence of photosensitizer selection and the polymer electrolyte composition on the performance of quasi-solid-state dye-sensitized solar cells (QsDSSCs). Two benchmark ruthenium dyes, N719 and Z907, alongside a novel photoactive phenothiazine dye were used. Each dye was incorporated into a QsDSSC architecture employing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the gel electrolyte matrix, with varying molecular weights, to investigate their impacts on the overall device performance and long-term stability. Our results demonstrated that the N719 dye exhibited the highest power conversion efficiency (PCE), attributed to its strong absorption in the visible spectrum and efficient electron injection into the TiO2 photoanode. Z907, on the other hand, showed moderate PCE due to its broader absorption profile but slower electron injection kinetics. The phenothiazine dye revealed promising PCE, with tunable absorption properties and efficient charge transfer. Furthermore, the impact of PVDF-HFP polymer gel electrolytes with varying molecular weights on cell stability was explored. The QsDSSC incorporating the PVH80 polymer with the phenothiazine dye exhibited reduced dye desorption, due to the effective dye molecules’ immobilization by the gel matrix, and consequently enhanced long-term stability over 600 h. This comparative study sheds light on the interplay between dye selection, the polymer gel’s properties, and QsDSSCs’ performance. These insights are crucial in designing robust and efficient QsDSSCs for practical applications.

As a representative flexible piezoelectric polymer, polyvinylidene fluoride (PVDF) and its copolymers have been widely used in energy harvesters and piezoelectric sensors. In this work, hybrid nanocomposite films were prepared by adding a small amount of carbon black (CB) and Ni nanoparticles to the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix using the solution casting method, followed by stretching and poling to increase the electroactive β-phase content. The results show that the hybrid fillers consisting of 0.3 wt% CB and 0.1 wt% Ni nanoparticles exhibit the best piezoelectric performance. The maximum output voltage of the PVDF-HFP/CB/Ni films reaches 3.5 V under 1 mm micro-vibration, which is 75% higher than that of pure PVDF-HFP films. Characterization results by X-ray diffraction analysis, Fourier-transform infrared spectrometry, and differential scanning calorimeter analysis show that the hybrid fillers are more effective in promoting the phase transformation from the α-phase to the β-phase in the matrix due to synergistic effect.

In this study, flexible nanocomposites made from PVDF-HFP reinforced with carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are manufactured using a sonication and solvent casting method for monitoring purposes. More specifically, the effect of the volume batch under the sonication process is explored. For CNT-based composites, the electrical conductivity decreases as the batch volume increases due to less effective dispersion of the CNTs during the 30-min sonication. The maximum electrical conductivity achieved in this type of sensor is 1.44 ± 0.17 S/m. For the GNP-based nanocomposites, the lower the batch volume is, the more breakage of nanoplatelets is induced by sonication, and the electrical response decreases. This is also validated by AC analysis, where the characteristic frequencies are extracted. Here, the maximum electrical conductivity measured is 8.66 ± 1.76 S/m. The electromechanical results also show dependency on the batch volume. In the CNT-based nanocomposites, the higher gauge factor achieved corresponds to the batch size, where the sonication may be more effective because it leads to a dispersed pathway formed by aggregates connected by tunneling mechanisms. In contrast, in the CNT-based nanocomposites, the GF depends on the lateral size of the GNPs. The biggest GF of all sensors is achieved with the PVDF-HFP/GNP sensors, having a value of 69.36 × 104 at 35% of strain, while the highest GF achieved with a PVDF-HFP/CNT sensor is 79.70 × 103 at 70%. In addition, cycling tests show robust electromechanical response with cycling for two different strain percentages for each type of nanocomposite. The sensor with the highest sensitivity is selected for monitoring two joint movements as proof of the applicability of the sensors manufactured.

Nowadays, bacterial infection is regarded as a serious threat to humankind, which needs to be taken care of. The emergence of antibiotic resistance and multidrug resistance (MDR) is rendering this situation more troublesome. However, several alternative treatment regimens have aided such diseases quite well in the recent past, among which dynamic antibacterial therapies combat this situation quite well. Among various dynamic therapies, piezodynamic therapy is a very recent avenue, in which mechanical stimuli have been exploited to treat bacterial infections. Herein, piezo-active bismuth ferrite-loaded poly(vinylidene fluoride-co-hexafluoropropylene) polymer has been utilized to eradicate gram-positive bacteria (E. faecalis) and gram-negative bacteria (E. coli). The sample has been designed in a free-standing membrane form, which, under soft ultrasound (~10 kHz), generates reactive radicals to ablate bacteria. Initially, the structure and morphology of the membrane have been substantiated by using X-ray diffraction and scanning electron microscopy methods; besides, Fourier transform infrared spectrum of the sample depicts a tremendously high value of polarizability and further confirms the piezo-activity of the membrane. More than 99% of E. coli and E. faecalis have been successfully eradicated within 30 min of ultrasound. Moreover, the solid-state structure and hydrophobic nature of the membrane help us to reuse it in a cyclic manner, which is possibly reported herein for the very first time. This novel membrane could be deployed in healthcare systems and pigment industries and could be exploited as a self-cleaning material. [ABSTRACT FROM AUTHOR]

This research aims to fabricate hydrophobic electrospun air filters with ultra-high performance against virions. In order to achieve this goal, constant basis weight electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with low-bead, high-bead, and ultra-high-bead fibre structures were used to fabricate single and multilayer filters by controlling the Dimethylformamide (DMF)-to-acetone ratio of the solvent. The water contact angle of the fabricated layers ranged from 131° for low-bead structures to 135° for ultra-high-bead structures, indicating their overall high hydrophobicity. The size-resolved filtering efficiency and pressure drop tests on the fabricated filters showed that low-bead structure for both single and multilayer filters and high-bead structure for single-layer filters enhance the quality factor remarkably. The results showed that the single-layer ultra-high-bead structure air filters had a filtering efficiency of 99.33%, superior to N95 air filters (96.54%) and comparable to double N95 filters (99.86%). However, the electrospun air filter showed a pressure drop of 169.3 Pa and a quality factor of 27.6 × 10 − 3   P a − 1 compared to a pressure drop of 388 Pa and quality factor of 16.9 × 10 − 3   P a − 1 for double N95 air filters. Therefore, it has a high potential to be used as the filtration media in hospitals, long-term care centers, and masks to provide superior protection against virions for healthcare providers and patients. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) based on ionic liquid (IL) were created using poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer mixed with 30 wt.% sodium thiocynate and varying weight ratios of EMIm-TCM ranging from 0 wt.% to 300 wt.%. The structural, electrical, thermal, morphological, and electrochemical features of the SPEs films, showing the effects of PVDF-HFP and the level of IL loading, have all been carefully examined. With the addition of IL, the mechanical qualities and mechanical stability of PVDF-HFP were enhanced, getting closer to the smaller usage for liquid electrolytes in energy devices. With the addition of 300 wt.% IL, the maximum ionic conductivity of 10−3 S cm−1 was attained. Additionally, the presence of the amorphous region in the IL-based electrolyte supported the movement of the EMIm + and TCM − ions in the PVDF-HFP chains, as shown by polarized optical microscopy and the ionic transference number. Due to their strong ionic conductivity, good mechanical attributes, and potential for long-term use in electrical double-layer capacitor applications, the developed PVDF-HFP/NaSCN/EMIm-TCM complex-based SPEs are particularly promising, showing the specific capacitance of 10 Fg−1. [ABSTRACT FROM AUTHOR]

Polymer-based separators for energy storage applications are being developed to ensure the high safety, high performance, light weight, and low cost of the device. In this regard, poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP which is a co-polymer of PVDF is an excellent host polymer for energy storage applications as it possess both the crystalline PVDF and the amorphous HFP groups leading to both mechanical stability and ionic conductivity. Though the lithium-ion-conducting PVDF-HFP membranes are successfully utilized as the polymer electrolyte for lithium ion batteries, the enhanced ionic conductivity by usage of plasticizers often degrade their mechanical and thermal stability. Where else, when incorporated with graphene oxide (GO) as the filler, the membrane electrolytes show good ionic conducting nature, with no compromise on thermal stability and mechanical stability. Incorporation of GO results in porous nature and helps in the high electrolyte retention and electrochemical stability even at high potential window. In this review article, the influence of GO with respect to structural changes, thermal stability, and electrical properties is discussed in detail, which will pave way for further new aspects in membrane modification. [ABSTRACT FROM AUTHOR]

Lithium-ion conducting solid electrolytes has been playing a vital role in designing solid-state lithium batteries to provide a propitious solution for the upcoming generation of energy storage devices that need to store more energy with a high degree of safety. Among different lithium-ion conductors, Li1.5Al0.5Ti1.5(PO4)3, a NASICON-type ceramic, has received attraction due to its good air stability and high lithium-ion conductivity. Herein, tellurium incorporated lithium aluminum titanium phosphate (Li1.3Al0.3Te0.03Ti1.67(PO4)3) (LATTP) has been prepared by solid-state reaction method. Further, the various amounts of LATTP incorporated electro-spun composite polymer electrolytes are prepared by using poly(vinylidenefluoride-hexafluoropropylene) (PVdF-HFP) polymer. Herein, we observed that 8 wt% of LATTP incorporated PVdF-HFP composite polymer electrolyte (CPE-8) exhibited high ionic conductivity of 1.9 × 10−3 S cm−1 at 30 °C, and enhanced lithium dendrite suppression and relatively lesser interfacial stability issues. Remarkably, LATTP incorporated CPE-8 shows improved cycling performance over 200 cycles compared to LATTP free (CPE-0). [ABSTRACT FROM AUTHOR]

Membrane technologies and materials development appear crucial for the hydrogen/natural gas separation in the impending transition to the hydrogen economy. Transporting hydrogen through the existing natural gas network could result less expensive than a brand-new pipe system. Currently, many studies are focused on the development of novel structured materials for gas separation applications, including the combination of various kind of additives in polymeric matrix. Numerous gas pairs have been investigated and the gas transport mechanism in those membranes has been elucidated. However, the selective separation of high purity hydrogen from hydrogen/methane mixtures is still a big challenge and nowadays needs a great improvement to promote the transition towards more sustainable energy source. In this context, because of their remarkable properties, fluoro-based polymers, such as PVDF-HFP and NafionTM, are among the most popular membrane materials, even if a further optimization is needed. In this study, hybrid polymer-based membranes were deposited as thin films on large graphite surfaces. Different weight ratios of PVDF-HFP and NafionTM polymers supported over 200 μm thick graphite foils were tested toward hydrogen/methane gas mixture separation. Small punch tests were carried out to study the membrane mechanical behaviour, reproducing the testing conditions. Finally, the permeability and the gas separation activity of hydrogen/methane over membranes were investigated at room temperature (25 °C) and near atmospheric pressure (using a pressure difference of 1.5 bar). The best performance of the developed membranes was registered when the 4:1 polymer PVDF-HFP/NafionTM weight ratio was used. In particular, starting from the 1:1 hydrogen/methane gas mixture, a 32.6% (v%) H2 enrichment was measured. Furthermore, there was a good agreement between the experimental and theoretical selectivity values. [ABSTRACT FROM AUTHOR]

Ball milling was used to prepare nanocrystalline TiO2, GO and PVDF-HFP/TiO2/GO nanocomposite, and the effects of milling hours on phase transformation and crystal size wasinvestigated. The films were made using the doctor blade method. XRD, SEM, FTIR spectra were used to characterize the prepared samples. The dielectric constant values were calculated for different milling hour. A lightweight, low-power film is described here for controlling the engagement in a mobile cleaning device. Electrostatic adhesion between thin electrode sheets covered with a dielectric substance underpins the film. The load bearing is influenced by the GO to TiO2 wt.%. A portable device has been fabricated based on the concept of electroadhesion. [ABSTRACT FROM AUTHOR]

This study is concerned with the nonlinear creep characteristics of extruded Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dominated by β-phase polymorphs over the temperature range 40 °C − 80 °C and tensile stress levels between 5 MPa and 12.5 MPa. The measured data using the developed experimental setup as well as the dynamic mechanical analyzer invariably suggested a nonlinearity taking place at temperatures near to 60 °C, where αc-relaxation began corresponding to 100 °C above the measured glass transition temperature of PVDF-HFP. The results from accelerated testing conditions indicated the transition to tertiary creep stage at 24% to 28% strain, irrespective of test condition, referred to as critical strain range. Following the identification of Findley power law model constant at different test conditions, a generalized temperature- and stress-dependent model was developed with only 7 constants. The comparisons between the measured and modeled data conveyed the model effectiveness in describing the nonlinear creep characteristics of the polymer over the measured temperature and stress levels. Time-temperature-compliance master curves were consequently constructed using the developed generalized model, which in combination with the critical strain failure criterion, provided the essential design data including the maximum allowable ranges of stress and temperature for achievement of 20 years creep life.

This study presents the potential of sulfonated poly (ether-ether-ketone)/ poly (vinylidene fluorideco-hexafluoro propylene)/SiO2 (SPEEK/PVdF-HFP/SiO2) composite proton exchange membrane for the use of microbial fuel cell. Silica particles (SiO2) were admixed with SPEEK/PVdF-HFP with various ratios. Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetric (DSC) were examined for characterizing the PEM membrane. Proton conductivity, oxygen diffusivity, ion exchange capacity (IEC), water uptake and performance for polymer composites using MFCs were analysed. The highest proton conductivity value of 8 × 10−2 S cm−1 was obtained for the SiO2–7.5 wt.% incorporated polymer membrane of SPEEK (80 wt.%) / PVdF-HFP (20 wt.%). The maximum voltage generation and power density of 998.5 ± 2 mV and 1.5 mW/m2 were noticed, respectively. This study suggests that the incorporation of SiO2 in polymer composite membrane has potential for an alternative PEM.

Lithium metal is considered as the most potential anode for next generational high energy density lithium‐ion battery. But due to high activity, the whole manufacturing process of LMA must be protected by inert gas and placed in dry environment, which will increase the significant production cost. The security risk is also increased once unexpected overheating happens. Therefore, prior to the practical application of LMA, these critical issues should be solved. A flame retardant, triphenyl phosphate (TPP), is introduced in this paper. When used as a protective layer on the surface of LMA, it can improve air tolerance of LMA even in a RH 70 % environment. In addition, PVDF‐HFP/TPP complex separator can be constructed via blade casting process, which plays an efficient role in increasing heat stability and flame retardancy. And more meaningfully, the composite separator is expected to form a coating layer by hot‐rolling with LMA, enabling LMA remain stable while in regular production environment. Such a strategy has the function of cutting costs and high temperature protection. [ABSTRACT FROM AUTHOR]

Growing environmental concerns are stimulating researchers to develop more and more efficient materials for environmental remediation. Among them, polymer-based hierarchical structures, attained by properly combining certain starting components and processing techniques, represent an emerging trend in materials science and technology. In this work, graphene oxide (GO) and/or carbon nanotubes (CNTs) were integrated at different loading levels into poly (vinyl fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and then electrospun to construct mats capable of treating water that is contaminated by methylene blue (MB). The materials, fully characterized from a morphological, physicochemical, and mechanical point of view, were proved to serve as membranes for vacuum-assisted dead-end membrane processes, relying on the synergy of two mechanisms, namely, pore sieving and adsorption. In particular, the nanocomposites containing 2 wt % of GO and CNTs gave the best performance, showing high flux (800 L × m−2 h−1) and excellent rejection (99%) and flux recovery ratios (93.3%), along with antifouling properties (irreversible and reversible fouling below 6% and 25%, respectively), and reusability. These outstanding outcomes were ascribed to the particular microstructure employed, which endowed polymeric membranes with high roughness, wettability, and mechanical robustness, these capabilities being imparted by the peculiar self-assembled network of GO and CNTs. [ABSTRACT FROM AUTHOR]

Piezoelectric ceramic and composite materials are attractive for various applications, but they can be challenging to process. In this research, KNN-0.8ZnO with high density (ρ th =95 %), favorable microstructure, and suitable dielectric and piezoelectric properties (K=875, d 33 =125 pC/N, tanδ=0.01) was first synthesized. Additionally, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) copolymer, known for its advantageous piezoelectric and mechanical properties, was selected as the polymer phase. subsequently, the KNN-0.8ZnO/xPVDF-HFP composite samples with a 0–3 connectivity pattern were made with the cold sintering method. The Taguchi design of experiment (DOE) was employed to determine the optimal condition for maximizing the figure of merit (FOM). Furthermore, an analysis of variance (ANOVA) was carried out to evaluate the significance of individual factors on each measured property. Phase identification was performed using X-ray diffraction (XRD) analysis, while the microstructure was examined using scanning electron microscopy. Among the different composite samples fabricated using the L9 orthogonal array (OA) of the Taguchi method, the KNN-0.8ZnO/20PVDF-HFP composite containing 20 wt% polymer phase, that was cold-sintered under a pressure of 400 MPa at 200 ͦC for 2 h, exhibited the highest FOM value of 1.945Pm2/N. This result aligns with the optimal conditions predeicated by the Taguchi DOE method. The compressive strength of the KNN-0.8ZnO/20PVDF-HFP composite was assessed through a compression test, yielding a value of 207 MPa, while the elastic modulus was approximately 3 GPa. The findings of this study demonstrate that the cold sintering method is an effective approach for producing dense piezoelectric composites with favorable electrical and mechanical properties, along with a high FOM for energy harvesting applications. • A new KNN-0.8ZnO/PVDF-HFP composite is made with cold sintering and the Taguchi design experiment was used to optimize the figure of merit. • KNN-0.8ZnO/20PVDF-HFP composite sample with 20 wt.% polymer, cold sintered with pressure of 400 MPa at 200 °C for 2 h, showed the best piezoelectric figure of merit. • The effective role of PVDF-HFP on dielectric, piezoelectric, and mechanical properties of KNN-ZnO/xPVDF-HFP composites cannot be ignored. • The cold sintering method is an efficient, simple and low-cost route to make dense 0-3 piezoelectric composites with favorable properties for energy harvesting applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF was grown on the MoS 2 surface using the solution self-assembly technique. • The Nanoscale Confinement Polarization Pinning effect was proposed for the first time. • Provided theoretical support for the application of porous MOFs heterojunctions in the field of enhanced piezoelectricity. • The piezoelectric sensor has a sensitivity of 0.183 V a−1 and a stability of 3000 cycles. • The prepared piezoelectric sensor can be used in the field of health monitoring and exercise assistance. In this study, a novel theory called Nanoscale Confinement Polarization Pinning (NCPP) theory is proposed. This theory provides theoretical support for the application of heterojunctions composed of porous metal–organic frameworks (MOFs) and conductors or semiconductors in enhancing the piezoelectric effect of piezoelectric polymers. The heterojunction formed between the metal–organic framework UIO-66(Hf)–NO 2 and MoS 2 enables the porous MOF to firmly pin the MoS 2 onto the molecular chains of PVDF-HFP. During polarization, MoS 2 , being highly susceptible to the electric field, drives the movement of PVDF-HFP's molecular chains through UIO-66(Hf)–NO 2 , this results in the molecular chains of PVDF-HFP aligning along the electric field, leading to a more orderly arrangement of the electric domains within PVDF-HFP and enhancing the piezoelectric effect, with the d 33 value increasing from 8 pC N−1 to 27 pC N−1. The size of UIO-66(Hf)–NO 2 is approximately 50 nm, with a conduction band of −0.93 eV and a bandgap of 2.56 eV, while MoS 2 has a size of approximately 400 nm, a conduction band of −0.62 eV, and a bandgap of 1.27 eV. When MoS 2 and UIO-66(Hf)–NO 2 form a heterojunction, an interfacial electric field is generated at the junction, under the influence of this electric field, the PVDF-HFP molecular chains that penetrate into UIO-66(Hf)–NO 2 tend to align, increasing the crystallinity of the composite nanofibers from 29.9 % to 35.0 %. This study broadens the application of heterojunctions formed by porous metal–organic frameworks with other conductors or semiconductors to enhance piezoelectricity, providing theoretical support. [ABSTRACT FROM AUTHOR]

Wearable sensor technology has garnered increasing attention among researchers. In this study, the porous metal-organic framework containing nitroxide (UIO-66-NO 2) is pasted onto MXene by hydrogen bonding and then incorporated into PVDF-HFP for electrospinning to fabricate piezoelectric membranes. The porous structure of the metal-organic frameworks significantly contributes to the alignment of electric domain orientation within the piezoelectric membranes post-polarization, and the nitro of UIO-66-NO 2 helps to enhance the inductive power effect of the sensor, the piezoelectric constant of the composite piezoelectric membrane reaches 26.1 pC/N, 5.8 times that of the pure PVDF-HFP membrane (4.5 pC/N). The sensitivity reaches 20.99 V/N, which is 5.75 times that of the pure PVDF-HFP sensor (3.65 V/N). We conduct an exploration into the potential mechanisms behind the enhanced piezoelectric properties resulting from the incorporation of MXene and the metal-organic framework. The fabricated flexible pressure sensor exhibits commendable cyclic stability, boasting rapid response and recovery time (20/10.8 ms). The sensor demonstrates the capability to monitor human respiration and pulse, discern various parts of the human body and their respective amplitudes, differentiate between different materials, the pressure sensor has potential applications in human-computer interaction and health monitoring. [Display omitted] • UIO-66-NO 2 is self-assembled on monolayer MXene surface via hydrogen bonding. • The "nanoconfinement effect" of UIO-66-NO 2 and MXene would enhance piezoelectric effect. • The composite membrane has a piezoelectric constant (d 33) of 26.1 pC/N. • The sensor has high sensitivity (20.99 V/N) and fast recovery time (10.8 ms). • The sensor is able to monitor faint breathing and pulse. [ABSTRACT FROM AUTHOR]

[Display omitted] • PVDF-HFP addition is a key factor contributing to enhanced performance and stability of solar cells in space environments. • PVDF-HFP PSCs showed an improved PCE of 22.54% over pristine due to increased carrier lifetimes and reduced charge transport resistance. • PVDF-HFP addition enhances the crystallinity and stability of perovskite films in vacuum conditions. • PVDF −HFP PSCs demonstrated significantly better resilience compared to pristine PSCs under gamma-ray exposure. Metal halide perovskites have sparked considerable interest in photovoltaic (PV) research due to their exceptional optoelectronic attributes. The remarkable power conversion efficiency (PCE), superior power-to-weight ratios, adaptability to flexible substrates, and robust radiation tolerance position perovskite solar cells (PSCs) as a compelling option for futuristic space PV applications. In this study, we enhance the stability of PSCs by incorporating the additive poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) into the perovskite composition and evaluate their performance under vacuum and gamma-ray irradiation conditions. The fluorine content in PVDF-HFP establishes strong hydrogen bonding with the perovskite's organic cations and coordination bonds with Pb2+ ions, facilitating effective defect mitigation within the perovskite matrix. PVDF-HFP PSCs showed a marked increase in PCE of 22.54 %, comparing to 19.85 % for the pristine one. Furthermore, PVDF-HFP PSCs retained 70 % of their initial PCE after 600 h in a vacuum environment (2 × 10-7 torr). Additionally, it exhibited strong resilience to gamma-ray exposure. These results indicate that the integration of PVDF-HFP as an additive in perovskite solar cells significantly enhances their stability and performance in the harsh space condition. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are popular energy storage devices due to their high energy density. Solid electrolytes appear to be a potential replacement for flammable liquid electrolytes in lithium batteries. This inorganic/hybrid solid electrolyte is a composite of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, (poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) polymer and sodium superionic conductor (NASICON)-type Li1+xAlxTi2−x(PO4)3 (LATP) ceramic powder. The structure, morphology, mechanical behavior, and electrochemical performance of this composite solid electrolyte, based on various amounts of LiTFSI, were investigated. The lithium-ion transfer and conductivity increased as the LiTFSI lithium salt concentration increased. However, the mechanical strength apparently decreased once the percentage of LITFSI was over 60%. The hybrid electrolyte with 60% LiTFSI content showed high ionic conductivity of 2.14 × 10−4 S cm−1, a wide electrochemical stability window (3–6 V) and good electrochemical stability. The capacity of the Li|60% LiTFSI/PVDF-HFP/LATP| LiFePO4 solid-state lithium-metal battery was 103.8 mA h g−1 at 0.1 C, with a high-capacity retention of 98% after 50 cycles. [ABSTRACT FROM AUTHOR]

In this research, the influences of the addition of PVP to PVDF-HFP polymers and the preparation of thin films using a solvent casting method were studied. The PVDF-HFP and polymer blend PVDF-HFP/PVP thin films with a nanostructured surface were investigated using scanning electron microscopy, differential scanning calorimetry, nanoindentation, and dielectric spectroscopy. The results showed that the PVP formed a dispersed phase (the poorer conductive islands) in the PVDF-HFP polymer matrix, which reduced its mechanical properties. The crystallinity of PVDF-HFP polymer decreased with the addition of PVP by 7.4%, but the PVP induced the formation of the polar β-phase of PVDF-HFP. Therefore, an improved dielectric response is expected, but it was not significantly improved even though the polar β-phase was detected. The contrasting effect was attributed to less conductive PVP islands on the surface of the PVDF-HFP/PVP polymer blend, which decreased its conductivity. [ABSTRACT FROM AUTHOR]

This research aims to fabricate hydrophobic electrospun air filters with ultra-high performance against virions. In order to achieve this goal, constant basis weight electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with low-bead, high-bead, and ultra-high-bead fibre structures were used to fabricate single and multilayer filters by controlling the Dimethylformamide (DMF)-to-acetone ratio of the solvent. The water contact angle of the fabricated layers ranged from 131° for low-bead structures to 135° for ultra-high-bead structures, indicating their overall high hydrophobicity. The size-resolved filtering efficiency and pressure drop tests on the fabricated filters showed that low-bead structure for both single and multilayer filters and high-bead structure for single-layer filters enhance the quality factor remarkably. The results showed that the single-layer ultra-high-bead structure air filters had a filtering efficiency of 99.33%, superior to N95 air filters (96.54%) and comparable to double N95 filters (99.86%). However, the electrospun air filter showed a pressure drop of 169.3 Pa and a quality factor of 27.6×10−3 Pa−1compared to a pressure drop of 388 Pa and quality factor of 16.9×10−3 Pa−1 for double N95 air filters. Therefore, it has a high potential to be used as the filtration media in hospitals, long-term care centers, and masks to provide superior protection against virions for healthcare providers and patients.

Nowadays, bacterial infection is regarded as a serious threat to humankind, which needs to be taken care of. The emergence of antibiotic resistance and multidrug resistance (MDR) is rendering this situation more troublesome. However, several alternative treatment regimens have aided such diseases quite well in the recent past, among which dynamic antibacterial therapies combat this situation quite well. Among various dynamic therapies, piezodynamic therapy is a very recent avenue, in which mechanical stimuli have been exploited to treat bacterial infections. Herein, piezo-active bismuth ferrite-loaded poly(vinylidene fluoride-co-hexafluoropropylene) polymer has been utilized to eradicate gram-positive bacteria (E. faecalis) and gram-negative bacteria (E. coli). The sample has been designed in a free-standing membrane form, which, under soft ultrasound (~10 kHz), generates reactive radicals to ablate bacteria. Initially, the structure and morphology of the membrane have been substantiated by using X-ray diffraction and scanning electron microscopy methods; besides, Fourier transform infrared spectrum of the sample depicts a tremendously high value of polarizability and further confirms the piezo-activity of the membrane. More than 99% of E. coli and E. faecalis have been successfully eradicated within 30 min of ultrasound. Moreover, the solid-state structure and hydrophobic nature of the membrane help us to reuse it in a cyclic manner, which is possibly reported herein for the very first time. This novel membrane could be deployed in healthcare systems and pigment industries and could be exploited as a self-cleaning material.

A solution-cast process was used to prepare pure poly (methyl methacrylate) (PMMA), and pure poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), their blend, and different weight percentages of sodium per chlorate (NaClO4) salt added to PMMA: PVdF-HFP polymer blend electrolyte thin films. The polymer electrolyte film was prepared using the solution cast process, which involves combining sodium per chlorate (NaClO4) ionic slat with poly (methyl methacrylate) (PMMA) and pure poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) blended polymer. These films have been characterized systematically using different experimental techniques to investigate structural, morphological, thermal, and conductivity properties. The degree of crystallinity and porous microstructure of all the thin films were determined by XRD and SEM data and revealed that higher content of the amorphous nature was noticed at higher NaClO4 salt concentration in PMMA:PVdF-HFP polymer blend. When NaClO4 salt was added to a PMMA:PVdF-HFP polymer blend, fair complexation/interaction between polymers and salt was observed. In DSC curves of PMMA and PVdF-HFP polymers, a sharp melting temperature (Tm) was seen, which diminished when NaClO4 salt was added, showing that its amorphous nature had risen to prominence. The ionic conductivity of NaClO4 salt added PMMA:PVdF-HFP polymer blend electrolyte has been investigated, with an optimal value found to be1.55382 x 10-4S/cm at 40% NaClO4 salt. Electrochemical cells have been fabricated and investigated its characteristics in the configuration of Na/[PMMA:PVdF-HFP: NaClO4]/(I2:C). [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) and its copolymers exhibit excellent piezoelectric properties and are potential materials for high efficiency energy harvesting devices. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films are prepared by the solution casting method. The prepared film is then subjected to mechanical stretching and poling process. By adjusting the temperature of the poling process and the elongation ratio of the mechanical stretching process, the relative content of β-phase F(β) increases significantly, leading to high piezoelectric performance. The maximum output voltage of the PVDF-HFP films poled at 40°C reaches 3.67 V, 71% higher than that of the films poled at room temperature. Fourier transform infrared spectroscopy analysis (FTIR), XRD (X-ray diffraction), and differential scanning calorimetry are used to investigate the influences of mechanical stretching and poling process on the crystal structure to discover the enhancement mechanism. This work provides a straightforward and low-cost route to prepare high piezoelectric PVDF-HFP-based materials.

As climatic conditions worsen and time passes, icing becomes an unavoidable issue. Drawing inspiration from the thermal regulatory properties inherent in polar bear fur, we introduce a biomimetic three-layer film. This film comprises a hydrophobic shield, a photothermal conversion layer, and an insulating layer through electrospinning. The multilayered micro/nanostructure within this film amplifies its light absorption capabilities, achieving an average absorption rate of 96.27 % across wavelengths ranging from 200 to 2500 nm. Thanks to the insulation layer's thoughtful design, the film boasts high photothermal conversion efficiency. When exposed to solar radiation for 360 s at an ambient temperature of 20 °C, its surface temperature swiftly climbs to 98.3 ± 1.1 °C. The film's anti-icing capabilities are evidenced by the fact that a droplet of water takes 2964.7 s to freeze on its surface, which is approximately 118 times that of aluminum. Additionally, it demonstrates excellent photothermal de-icing performance, swiftly eliminating thick layers of ice or frost under sunlight. Moreover, this film maintains its anti-icing and hydrophobic qualities even after multiple icing and de-icing cycles, as well as durability testing. It also possesses self-cleaning properties. Given its outstanding performance, this film has tremendous potential for long-term outdoor anti-icing applications. [Display omitted] • PDMS@MWCNTs/PVDF-HFP(P@MP) was designed, inspired by polar bear fur. • Three-layer film with superhydrophobic and photothermal properties was fabricated. • Photothermal conversion efficiency was improved by low heat loss insulation layer. • The freezing time of P@MP is 118 times than that of Al. • P@MP with excellent anti-icing/de-icing, self-cleaning, and durability properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed polymer solid electrolyte membrane using solution casting method. • Achieved high ionic conductivity and strong mechanical properties in BPE membrane. • Demonstrated ultra-stable cycles and high-capacity retention in ASSLMBs. Polymer electrolytes have become widely popular on account of their low expenses, reduced weight, simple processing, and excellent safety features. However, polymer electrolytes have yet to find use in commercial batteries because of their limited mechanical durability and poor ionic conductivity. In this paper, an ultra-stable cycles and interfaces blending polymer electrolyte (BPE) suitable for all solid-state Li metal batteries was prepared by blending three polymers: polymethyl methacrylate (PMMA), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), and polyethylene oxide (PEO). Microstructure characterization showed numerous amorphous areas with strong interfacial strength of the BPE. The BPE3 exhibited a maximum of 15.65 MPa in tensile strength. BPE2 have excellent electrochemical performance, such as wide electrochemical windows (up to 4.7 V vs Li/Li+), high lithium ion transference numbers (up to 0.75), high ion conductivity (up to 1.87 × 10-4 S cm−1 at 60 °C), and excellent interface stability. By assembling all state-solid LiFePO 4 /BPE2/Li batteries for electrochemical testing, BPE2 exhibit high electrochemical characteristics. BPE2 discharge specific capacity is as high as 154.7 mAh g−1 at 1C. The BPE2 underwent 200 cycles at 0.5C and 400 cycles at 1C, with capacity retention rates of 95.7 % and 96.6 %, respectively. BPE is a promising electrolyte candidate for flexible lithium metal batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • A detailed review of modified PVDF and its copolymer based proton exchange membrane for DMFC is explained. • The physical and electrochemical characteristics of PVDF and its copolymer-made membranes are discussed. • The advantages of these different polymers for making membranes are compared. • The future prospects for improvement in this polymer membrane are highlighted. Direct methanol is a promising portable electronic device that converts chemical energy into electrical energy by using easily available and environmentally friendly methanol fuel. Among its different components, the proton exchange membrane (PEM) is responsible for continuing the flow of hydration ions from anode to cathode, protecting from fuel crossover and keeping the electrons pushing towards the external circuit, which produces power. The Nafion-based proton exchange membrane is widely studied in direct methanol fuel cells because of its easy wettability, high ion exchange capacity, minimum methanol crossover, and mechanical strength due to its nono-porous structure. However, the methanol crossover increases in the Nafion membrane due to easy swelling when temperature raise due to reactions in the direct methanol fuel cells (DMFC) and dramatically reduces overall cell performance. Several types of polymers have been applied as PEMs for the replacement of costly Nafion membranes. Among these polymers, polyvinylidene fluoride (PVDF) and its copolymers such as polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and poly (vinylidene fluoride-chlorotrifluoroethylene) (PVDF-CTFE) are considered effective for the production of high-class proton exchange membranes because of their less swollen nature, easy film forming ability, high mechanical strength, thermal stability and chemical inertness. Their easy modification with other hydrophilic polymers and nanoparticles as well as surface functionalization convert their hydrophobic nature that boosts proton conductivity. Moreover, the nano-porous structure with tortuous paths create with PVDF and copolymers efficiently reduces the methanol crossover. From high-crystalline PVDF to reduced-crystalline copolymers, effects on mechanical strength and water uptake of the proton exchange membrane. This review article presents the overall application of all PVDF family polymers and their modified forms as proton exchange membranes in direct methanol fuel cells. [ABSTRACT FROM AUTHOR]

Focusing on the uncontrolled discharge of organic dyes, a known threat to human health and aquatic ecosystems, this work employs a dual-functional catalyst approach, by immobilizing a synthesized bismuth sulfur iodide (BiSI) into a poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymeric matrix for multifunctional water remediation. The resulting BiSI@PVDF nanocomposite membrane (NCM), with 20 wt% filler content, maintains a highly porous structure without compromising morphology or thermal properties. Demonstrating efficiency in natural pH conditions, the NCM removes nearly all Rhodamine B (RhB) within 1 h, using a combined sonophotocatalytic process. Langmuir and pseudo-second-order models describe the remediation process, achieving a maximum removal capacity (Q max) of 72.2 mg/g. In addition, the combined sonophotocatalysis achieved a degradation rate ten and five times higher (0.026 min−1) than photocatalysis (0.002 min−1) and sonocatalysis (0.010 min−1). Furthermore, the NCM exhibits notable reusability over five cycles without efficiency losses and efficiencies always higher than 90%, highlighting its potential for real water matrices. The study underscores the suitability of BiSI@PVDF as a dual-functional catalyst for organic dye degradation, showcasing synergistic adsorption, photocatalysis, and sonocatalysis for water remediation. [Display omitted] • A BiSI@PVDF nanocomposite membrane was prepared and fully characterised. • A dual-functional catalyst approach was addressed, merging adsorption, sonocatalysis, and photocatalysis in a single method. • A Q max of 72.2 mg/g was achieved under US and VIS irradiation after 120 min. • The BiSI@PVDF exhibits notable reusability and performance in real water matrices. • The BiSI@PVDF is suitable for organic dye degradation, showcasing synergistic adsorption, photocatalysis, and sonocatalysis. [ABSTRACT FROM AUTHOR]

Chemical pollutants, such as methyl orange (MO), constitute the main ingredients in the textile industry wastewater, and specifically, the dyeing process. The use of such chemicals leads to huge quantities of unfixed dyes to make their way to the water effluent and consequently escalates the water pollution problem. This work investigates the incorporation of hydrophobic carbon nanospheres (CNS) prepared from the pyrolysis of acetylene using the chemical vapor deposition technique with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in order to enhance its hydrophobicity. Moreover, a deep eutectic solvent (DES) was used to enhance the membrane's porosity. The former was based on the quaternary ammonium salt (N,N-diethyl-ethanol-ammonium chloride) as a chemical addition throughout the membrane synthesis. Direct contact membrane distillation (DCMD) was employed to assess the performance of the modified membrane for treatment of MO contaminated water. The phase inversion method was used to embed various contents of CNS (i.e., 1.0, 3.0, and 5.0 wt.%) with 22:78 wt.% of PVDF-co-HFP/N-Methyl-2-pyrrolidone solution to prepare flat-sheet membranes. The membrane embedded with 5 wt.% CNS resulted in an increase in membrane hydrophobicity and presented considerable enhancement in DCMD permeation from 12 to 35 L/h.m2 with salt rejection >99.9%. Moreover, the composite membrane showed excellent anti-biofouling and mechanical characteristics as compared to the pristine counterpart. Using this membrane, a complete rejection of MO was achieved due to the synergistic contribution of the dye negative charge and the size exclusion effect. [ABSTRACT FROM AUTHOR]