Vinylidene Fluoride Research Articles

Assemblable 3D biomimetic microenvironment for hMSC osteogenic differentiation

Abstract The suitable simulation of a tissue’s native environment is one of the elemental premises of tissue engineering. Although various attempts have been made to induce human mesenchymal stem cells (hMSC) into an osteogenic pathway, they are still far from widespread clinical application. Most strategies mainly focus on providing a specific type of cue, far from replicating the complexity of the bone microenvironment. By applying magnetoelectric microspheres composed of poly(vinylidene fluoride) (PVDF) and cobalt ferrites, functionalized with collagen and gelatin, and packed in a 3D arrangement, a multifunctional platform for hMSC osteogenic differentiation has been developed. This platform is able to perform mechanical stimulation of piezoelectric PVDF, mimicking the bones biophysical electromechanical cues. Surface functionalization with extracellular matrix (ECM) biomolecules and osteogenic media further contribute to this all-round approach. hMSC were cultured in osteogenic-inducing conditions in order to induce them into this pathway and tested for proliferation, surface biomarkers, and gene expression to evaluate their osteogenic commitment.

Laccase–Cu3BTC2 Prepared via a Biomimetic Mineralization Method and Its Effect on the Performance of a Poly(vinylidene fluoride) (PVDF) Membrane (BTC = Benzene-1,3,5-tricarboxylate)

Laccase–Cu₃BTC₂ Prepared via a Biomimetic Mineralization Method and Its Effect on the Performance of a Poly(vinylidene fluoride) (PVDF) Membrane (BTC = Benzene-1,3,5-tricarboxylate)

Achieving Significantly Boosted Dielectric Energy Density of Polymer Film via Introducing a Bumpy Gold/Polymethylsilsesquioxane Granular Blocking Layer.

Polymer dielectrics are the key materials for pulsed energy storage systems, but their low energy densities greatly restrict the applications in integrated electronic devices. Herein, a unique bumpy granular interlayer consisting of gold nanoparticles (Au NPs) and polymethyksesquioxane (PMSQ) microspheres is introduced into a poly(vinylidene fluoride) (PVDF) film, forming trilayered PVDF-Au/PMSQ-PVDF films. Interestingly, the Au/PMSQ interlayer arouses a dielectric enhancement of 47% and an ultrahigh breakdown strength of 704MVm-1, which reaches 153% of pure PVDF. It is revealed that the greatly enhanced breakdown strength originated from the Coulomb-blockade effect of Au NPs and the excellent insulating properties of PMSQ microspheres with a special molecular-scale organic-inorganic hybrid structure. Benefiting from the concurrently enhanced dielectric and breakdown performances, an outstanding energy density of 22.42Jcm-3 with an efficiency of 67.1%, which reaches 249% of that of the pure PVDF, is achieved. It is further confirmed that this design strategy is also applicable to linear dielectric polymer polyethyleneimine. The composites exhibit an energy density of 8.91Jcm-3 with a high efficiency of ≈95%. This work offers a novel and efficient strategy for concurrently enhancing the dielectric and breakdown performances of polymers toward pulsed power applications.

Poling-Induced Wettability Transition of a Uniaxially Oriented Poly(vinylidene fluoride) Film

Poling-Induced Wettability Transition of a Uniaxially Oriented Poly(vinylidene fluoride) Film

Polymer Coating Enabled Carrier Modulation for Single-Walled Carbon Nanotube Network Inverters and Antiambipolar Transistors.

The control of the performance of single-walled carbon nanotube (SWCNT) random network-based transistors is of critical importance for their applications in electronic devices, such as complementary metal oxide semiconducting (CMOS)-based logics. In ambient conditions, SWCNTs are heavily p-doped by the H2O/O2 redox couple, and most doping processes have to counteract this effect, which usually leads to broadened hysteresis and poor stability. In this work, we coated an SWCNT network with various common polymers and compared their thin-film transistors' (TFTs') performance in a nitrogen-filled glove box. It was found that all polymer coatings will decrease the hysteresis of these transistors due to the partial removal of charge trapping sites and also provide the stable control of the doping level of the SWCNT network. Counter-intuitively, polymers with electron-withdrawing functional groups lead to a dramatically enhanced n-branch in their transfer curve. Specifically, SWCNT TFTs with poly (vinylidene fluoride) coating show an n-type mobility up to 61 cm2/Vs, with a decent on/off ratio and small hysteresis. The inverters constructed by connecting two ambipolar TFTs demonstrate high gain but with certain voltage loss. P-type or n-type doping from polymer coating layers could suppress unnecessary n- or p-branches, shift the threshold voltage and optimize the performance of these inverters to realize rail-to-rail switching. Similar devices also demonstrate interesting antiambipolar performance with tunable on and off voltage when tested in a different configuration.

Scalable wet-spinning multilevel anisotropic structured PVDF fibers enhanced with cellulose nanocrystals-exfoliated MoS2 for high-performance piezoelectric textiles

The high-performance fabric-based piezoelectric nanogenerators (PENGs) is the ideal choice for the next generation of wearable electronics. However, large-scale fabrication of high-performance fabric-based PENGs remains a great challenge. In this study, cellulose nanocrystals (CNCs) exfoliated MoS2 (C@M) are integrated into the poly (vinylidene fluoride) (PVDF) matrix, which are successfully fabricated PVDF/C@M fibers (PCF) by wet-spinning and post-drawing processes. Accompanied by the stress-induced anisotropic alignment of C@M and PVDF molecular chains during post-drawing, the interfacial interactions between C@M and PVDF dipoles greatly promote the formation of the electroactive β-phase of PVDF as well as the orientation of the dipoles. The PCF demonstrate excellent mechanical performance with a tensile strength of 301 MPa and toughness of 68.5 MJ·m−3. Subsequently, the PCF are woven into fabrics and subsequently assembled into a flexible PENG (PCF-PENG), exhibiting excellent piezoelectric coefficient (d33 = 40.3 pC·N−1), power density of 56.25 μW·cm−2. Furthermore, scenarios such as energy harvesting, motion detection, and posture recognition of the PCF-PENG are demonstrated, providing a feasible proposal for the large-scale fabrication of electronic textiles.

A self-adaptive inorganic in-situ separator by particle crosslinking for nonflammable lithium-ion batteries

All-safe liquid-state lithium-ion batteries (ASLS-LIBs) is of great interest as they can potentially combine the safety of all-solid-state batteries with the high performance and low manufacturing cost of traditional liquid-state LIBs. However, the practical success of ASLS-LIBs is bottlenecked by the lack of advanced separator technology that can simultaneously realize high performances in puncturing-tolerability, fire-resistance, and importantly, wetting-capability with non-flammable liquid-electrolytes. Here, we propose a concept of inorganic in-situ separator (IISS) by hybrid-sol physical crosslinking directly onto the electrode surface to address the above challenges. Particularly, the hybrid-sol is designed with silica nanoparticles as the building block and poly(vinylidene difluoride) nanoparticles as the crosslinking agent. The critical factors for controlling the IISS microstructures and properties have been systematically investigated. The advantages of the IISS have been confirmed by its fast wetting with various fire-resistant liquid-electrolytes, customizable thickness and porous structures, robust interface with planar or three-dimensional (3D)-structured electrodes, and importantly, unexpected self-adaptability against puncturing. Enabled by the above merits, a fire-resistant ASLS-LIB is successfully assembled and demonstrated with stable electrochemical performance. This sol-crosslinked IISS may open an avenue for the studies on the next-generation separator technology, cell assembling, solid electrolyte processing as well as non-flammable secondary batteries.

Exploiting Metal-Organic Frameworks for Vinylidene Fluoride Adsorption: From Force Field Development, Computational Screening to Machine Learning.

Metal-organic frameworks (MOFs) represent a distinctive class of nanoporous materials with considerable potential across a wide range of applications. Recently, a handful of MOFs has been explored for the storage of environmentally hazardous fluorinated gases (Keasler et al. Science 2023, 381, 1455), yet the potential of over 100,000 MOFs for this specific application has not been thoroughly investigated, particularly due to the absence of an established force field. In this study, we develop an accurate force field for nonaversive hydrofluorocarbon vinylidene fluoride (VDF) and conduct high-throughput computational screening to identify top-performing MOFs with high VDF adsorption capacities. Quantitative structure-property relationships are analyzed via machine learning models on the combinations of geometric, chemical, and topological features, followed by feature importance analysis to probe the effects of these features on VDF adsorption. Finally, from detailed structural analysis via radial distribution functions and spatial densities, we elucidate the significance of different interaction modes between VDF and metal nodes in top-performing MOFs. By synergizing force-field development, computational screening, and machine learning, our findings provide microscopic insights into VDF adsorption in MOFs that will advance the development of new nanoporous materials for high-performance VDF storage or capture.

Investigating the electrochemical properties of poly(vinylidene fluoride)/polyaniline blends doped with lithium-based salt

Conductive polymers have attracted much attention in various applications, owing to their excellent chemical, thermal, and oxidative stability. However, they have low dielectric constant, which limits their performance in electrochemical devices. To overcome this drawback, blending with other polymers helps improving their electrochemical properties. Herein, we investigate structural and electrochemical properties of poly (vinylidene fluoride) (PVDF)/polyaniline (PANI) blends doped with lithium-based salt. Results showed that the blends exhibit phase separation of PANI and PVDF, which is confirmed by the thermodynamic interaction parameter. We found that the interaction between the two polymers enhanced the ionic conductivity from 4.9 × 10−5 S cm−1 for neat PVDF to 5.3 × 10−4 S cm−1 for composition of 50:50 (PANI50), whereas the ionic conductivity was inversely proportional to the temperature. Moreover, by adding lithium salt to the blend, the thermal stability increased from 376.6 to 478.5 °C for PANI50. The ionic conductivity of the blends depends on the PVDF content, which affects the interaction between the two polymers.

Enhancing Oxygen Sensing Properties of Plasticized PVC Films by Blending Poly (Vinylidene Fluoride-Co-Hexafluoropropylene)

Enhancing Oxygen Sensing Properties of Plasticized PVC Films by Blending Poly (Vinylidene Fluoride-<i>Co</i>-Hexafluoropropylene)

Surface functionalization of cellulose derived from hemp by tetraethyl orthosilicate (TEOS) and poly vinylidene fluoride (PVDF)-based composite separator membrane for lithium-ion batteries (LIBs)

Separators play a crucial role in enhancing the electrochemical performance of lithium-ion batteries (LIBs). However, achieving separators with exceptional electrochemical performance and high stability remains a significant challenge. In this study, we meticulously designed composite membranes based on polyvinylidene fluoride (PVDF) with varying contents of microcrystalline cellulose/tetraethyl orthosilicate (MCC/TEOS). The increase in hydrophilicity of PVDF by adding MCC-TEOS weight contents endowed the 3 wt% MCC/TEOS-based PVDF separator membrane with superior electrolyte absorption and reduced resistance, resulting in an impressive ionic conductivity of 0.514 mS/cm higher than the pristine PVDF membrane (0.253 mS/cm). Furthermore, the LIB cell utilizing the 3 wt % MCC/TEOS-based PVDF separator membrane consistently demonstrated stable charge/discharge profiles at a rate of 0.2C, achieving a specific capacity of 98 mAh/g, compared to only 43 mAh/g for the pristine PVDF membrane. These findings underscore the significant potential of MCC/TEOS as a biofiller for bio-membranes, making it an optimal choice for applications in LIBs.

Development of Transparent Self-Cleaning Coatings for Solar Panels: Spray-Coated Polydimethylsiloxane/Poly (vinylidene fluoride) (PVDF/PDMS)/TiO2 Approach

Development of Transparent Self-Cleaning Coatings for Solar Panels: Spray-Coated Polydimethylsiloxane/Poly (vinylidene fluoride) (PVDF/PDMS)/TiO2 Approach

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

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

The phase transition and enhanced dielectric properties in La0.7Ba0.3MnO3 /P(VDF-HFP) composited films

Polymer-based ferroelectric composites, particularly those containing Poly (vinylidene fluoride) (PVDF), have emerged as preferred materials for flexible electronics and sensors owing to their excellent electro-mechanical attributes and ease of fabrication. The efficacy of PVDF composites is significantly influenced by the fillers and the proportion of the β-phase present. This research details the synthesis of La0.7Ba0.3MnO3 (LBMO) particles via solid-state reaction, surface-functionalized with acetic acid, and subsequently introduced as nucleating agents into Poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) to fabricate LBMO/P(VDF-HFP) composite membranes. The LBMO fillers before modification significantly increased the β-phase content from 32.7 % to 87.8 % in 5 wt% unmodified LBMO/P(VDF-HFP) membranes. After modification, the hydroxyl groups attached to acetic acid-modified LBMO form hydrogen bonds with -CF2 groups in P(VDF-HFP), inducing the formation of the β phase while enhancing macroscopic polarization and piezoelectricity. At a 7.5 wt% acetate-modified LBMO doping level, the composite membrane exhibits a β-phase content of 64.5 %, but concurrently enhancing the film's dielectric properties. At 103 Hz, the dielectric constant of 5 wt% modified LBMO/P(VDF-HFP) membrane increases to 24.8, with a minimal rise in dielectric loss from 0.0293 to 0.0314. Moreover, under a 10 N compressive load at 1 Hz, the 5 wt% modified LBMO/P(VDF-HFP) composite achieves an open-circuit voltage of 4.3 V. These improved dielectric and piezoelectric properties indicate the composite's suitability for energy harvesting applications.

Piezoelectric Nanogenerators Based on Poly(vinylidene fluoride) Doped with High Entropy Oxide Nanoparticles for Sensitive Pressure Sensors

Piezoelectric Nanogenerators Based on Poly(vinylidene fluoride) Doped with High Entropy Oxide Nanoparticles for Sensitive Pressure Sensors

Fabrication of TiO2@ZIF-67 metal organic framework composite incorporated PVDF membranes for the removal of hazardous reactive black 5 and Congo red dyes from contaminated water

Novel application of TiO2@ZIF-67 composite incorporated poly (vinylidene fluoride) (PVDF) mixed matrix flat-sheet membranes for treating the water contaminated with hazardous reactive black 5 and congored dyes was the crux of this work. The composite was characterized by FTIR, BET, XRD, zeta potential and particle size, and TGA. The as-synthesized composite was embedded in the PVDF polymeric matrix and flat-sheet-membranes were fabricated adopting the NIPS method followed by the different characterizations like scanning electron microscopy, EDS, elemental mapping, contact angle, atomic force microscopy, surface energy, and XPS. Results of the performance studies showed an enhanced pure water permeability from 150.99 Lm-2h−1 for neat membrane to 261.39 Lm-2h−1 for TZM-2. The reactive black 5 dye was rejected in 97.4 %, 92.2 %, and 84.84 % in acidic, basic and neutral conditions respectively by TZM-2 membrane. Whereas, the PVDF membranes without the composite showed rejections of 83.19 %, 82.5 %, and 72.1 % respectively in acidic, basic, and neutral conditions. The Congo Red dye was rejected in 89.4 %, 95.68 %, and 92.4 % in acidic, neutral and basic conditions respectively by TZM-2 membranes. Whereas, the PVDF membranes without the composite showed rejections of 82.8 %, 91.9 %, and 85.4 % respectively in acidic, neutral and basic conditions.

Fabrication of omniphobic PVDF membrane with SiO2–FeOOH hierarchical structures for robust membrane distillation

Omniphobic membrane has been demonstrated as an effective strategy to mitigate membrane wetting and fouling risks in membrane distillation (MD) processes. In this work, novel omniphobic membranes with hierarchical re-entrant surface structure were fabricated. Firstly, the FeOOH nanorods were deposited on the polydopamine (PDA) pre-treated poly (vinylidene fluoride) PVDF membrane. After that, the SiO2 nanoparticles (NPs) were coated on the FeOOH nanorods via electrostatic attraction to form hierarchical structures. Finally, the fluorosilane was utilized to reduce the membrane surface free energy, contributing to PVDF based omniphobic membranes. The effects of reaction time, FeCl3·6H2O and SiO2 NPs concentrations on membrane properties, including membrane surface morphology, average pore size, contact angles (CAs), surface roughness and permeate flux, were investigated in detail. The resulting omniphobic membranes showed high CAs towards various tested liquids, such as 0.4 mM sodium dodecyl sulfate (SDS) solution (143.9 ± 0.8°), hexadecane (113.5 ± 3.2°) and mineral oil (132.5 ± 2.8°). This membrane exhibited outstanding performance in a continuous 50-h vacuum membrane distillation (VMD) process with a 10 wt% NaCl feed solution. Besides, the anti-oil-fouling properties were further assessed with a feed solution containing 200-ppm hexadecane and 3.5-wt% NaCl, the omniphobic membrane exhibited steady permeate flux of above 24.18 kg m−2 h−1 and a 99.99 % rejection rate during 50-h testing. Finally, the omniphobic membrane showed high anti-wetting properties by SDS/salt solution. This work introduces a new strategy for fabricating omniphobic membranes that shows significant potential for treating complex industrial wastewaters.

Deeper Spectroscopic Characterizations of Vinylidene Fluoride (VDF) Oligomers Prepared via Iodine Transfer Polymerization (ITP)

Deeper Spectroscopic Characterizations of Vinylidene Fluoride (VDF) Oligomers Prepared via Iodine Transfer Polymerization (ITP)

AC/DC Magnetic Field Sensing Based on a Piezoelectric Polymer and a Fully Printed Planar Spiral Coil.

Additive manufacturing (AM) is emerging as an eco-friendly method for minimizing waste, as the demand for responsive materials in IoT and Industry 4.0 is on the rise. Magnetoactive composites, which are manufactured through AM, facilitate nonintrusive remote sensing and actuation. Printed magnetoelectric composites are an innovative method that utilizes the synergies between magnetic and electric properties. The study of magnetoelectric effects, including the recently validated piezoinductive effect, demonstrates the generation of electric voltage through external AC and DC magnetic fields. This shift in magnetic sensors, utilizing piezoinductive effect of the piezoelectric polymer poly(vinylidene fluoride), PVDF, eliminates the need for magnetic fillers in printed devices, aligning with sustainability principles, essential for the deployment of IoT and Industry 4.0. The achieved sensitivity surpasses other studies by 100 times, showcasing linear outputs for both applied AC and DC magnetic fields. Additionally, the sensor capitalizes on the linear phase shift of the generated signal with an applied DC magnetic field, an unprecedented effect. Thus, this work introduces a remarkable magnetoactive device with a sensitivity of ST = 95.1 ± 0.9 μV Oe-1 mT-1, a significantly improved performance compared to magnetoelectric devices using polymer composites. As a functional proof of concept of the developed system, a magnetic position sensor has been demonstrated.

Enabling room temperature solid-state lithium batteries by blends of copolymers and ionic liquid electrolytes

High lithium-concentration phosphonium ionic liquids electrolytes have shown outstanding properties even overcoming ammonium derivatives in terms of viscosity and transport properties. Consequently, they have been also combined with fluorinated polymers, such as poly(vinylidene fluoride) (PVDF) or poly(ionic liquids), for solid-state batteries with satisfying performance at 50 °C. The aim of this work is to develop highly lithium conducting solid-state electrolyte (≥0.1 mS cm−1) at room temperature but maintaining solid-state properties. For this, polymer electrolytes based on ISOBAM alternating copolymer (isobutylene and maleic anhydride) and ionic liquid (P111i4FSI) were developed. The composition-dependent behavior of the solid electrolytes was studied in terms of electrochemical impedance spectroscopy (EIS), reaching σLi+ of 0.52 mS cm−1; differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) under different ionic liquid electrolyte loadings and salt concentration. The polymer electrolytes presented a solid-like behavior in the range of 25 to 90 °C with a storage modulus of 2.3·104 Pa. Finally, the best free-standing membrane electrolytes were tested and compared electrochemically in lithium symmetrical cells and lithium iron phosphate full cells exhibiting an excellent cycling at room temperature.