Search Results (445)

Polymer–ceramic piezoelectric composites are widely investigated to combine the high piezoelectric performance of ferroelectric ceramics with the flexibility and processability of electroactive polymers. However, achieving enhanced dielectric properties while preserving the intrinsic piezoelectric response of the polymer matrix remains challenging, particularly due to dielectric mismatch between the constituent phases and interfacial effects. In this work, barium titanate (BaTiO₃) loaded poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) nanocomposites were fabricated by solvent casting using polyvinylpyrrolidone (PVP) and polysorbate 80 (PS80) as dispersing agents, aiming to obtain polarizable materials capable of retaining high piezoelectric strain coefficient (d₃₃) values and potentially exploiting the opposite polarity of matrix and filler through tailored poling strategies. Morphological, crystallographic, structural, thermal, thermomechanical, dielectric, and piezoelectric characterizations were performed by SEM/EDXS, XRD, FTIR, DSC, TGA, DMTA, dielectric spectroscopy, and d₃₃ measurements. Both dispersants improved filler dispersion and film densification, increasing the crystalline fraction of the matrix, without altering the relative fraction of β-phase (up to 93%). PVP enabled moderate and stable permittivity enhancement with weak frequency dependence, whereas PS80 introduced an electrically active interfacial contribution that amplified low-frequency permittivity at high filler loadings but made the permittivity more frequency-dependent. The piezoelectric response (between −20 pC/N and −25 pC/N) remained predominantly governed by the polymer phase, suggesting limited polarization played by BaTiO₃. These results underlined the critical role of interfacial electrical properties in designing stable high-performance flexible PVDF-TrFE/BaTiO₃ composites. Full article

The development of durable and practical polymer-supported photocatalytic materials that are suitable for use in continuous-flow systems has become an increasingly pressing issue in the field of water treatment. In this study, FeTiO₃/BiOCl heterojunction structures were synthesized at different ratios and integrated into a poly(vinylidene fluoride) (PVDF) matrix to develop photocatalytic thin-film systems. The resulting materials were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and UV–visible diffuse reflectance spectroscopy (UV-DRS) analyses. In photocatalytic experiments conducted under visible light, a 66.3% removal of doxycycline was achieved for pristine FeTiO₃ within 180 min, whilst the FTO@BiOCl(III) composite reached 74.4%. In the PVDF-based thin-film system, the film catalyst demonstrated a removal efficiency of 68.9%. When the pH effect was investigated, the highest total removal of 90.3% was achieved under pH 6.0 conditions. Radical scavenging experiments revealed that superoxide radicals were the predominant active species (a decrease to 30.5% in the presence of benzoquinone (BQ). In experiments conducted in the air-lift reactor system, the P-FTO@BiOCl(III) film achieved approximately 65% removal after 9 h and maintained its structural stability. The PVDF-supported FeTiO₃/BiOCl heterojunction thin-film system offers a noteworthy alternative for environmental applications due to its suitability for continuous systems, structural stability and effective photocatalytic performance. Full article

Multifunctional polymer–ferrite composites based on poly(vinylidene fluoride) (PVDF) and magnetic fillers are of increasing interest for applications requiring coupled electrical, dielectric, and magnetic responses. However, the relationship between magnetic filler concentration, PVDF phase composition, and the resulting multifunctional properties remains insufficiently understood. In this work, PVDF/BaFe₁₂O₁₉ (PVDF/BaF) composite membranes containing 2–20 wt.% BaF were fabricated using a combined non-solvent and thermally induced phase-inversion (NIPS–TIPS) method. Structural evolution was analyzed by X-ray diffraction and quantitative FTIR spectroscopy, thermal behavior by differential scanning calorimetry, optical properties by diffuse reflectance spectroscopy, dielectric response in the frequency range 10³–10⁶ Hz, and magnetic characteristics by vibrating sample magnetometry. At moderate filler concentrations (2–10 wt.%), BaFe₁₂O₁₉ nanoparticles acted as effective β-phase nucleating centers, leading to electroactive phase fractions of 97.7–99.9% and a maximum β-phase content of 86.7% for PVDF/BaF10. At higher loadings (15–20 wt.%), particle agglomeration and restricted chain mobility promoted a transition toward α-phase-dominated crystallization. Thermal analysis indicated competing nucleation and confined crystallization processes, while optical and dielectric measurements revealed nonmonotonic changes associated with interfacial interactions and Maxwell–Wagner–Sillars polarization. Magnetic measurements showed a linear increase in saturation magnetization with filler concentration and a nonmonotonic coercivity dependence with a pronounced change near the critical agglomeration concentration. These results demonstrate that the multifunctional response of PVDF/BaFe₁₂O₁₉ membranes is governed by the interplay between β-phase nucleation, interfacial polarization, and magnetic particle interactions, with approximately 10 wt.% ferrite providing the most balanced electrical, dielectric, and magnetic characteristics. Full article

In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films embedded with silver nanoparticles were fabricated to investigate their antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Inspired by the nanoscale topographies of natural antibacterial surfaces, such as dragonfly and cicada wings, microstructured pillars were introduced onto the polymer surface to enhance its bactericidal activity by increasing the effective contact area. Surface morphology was characterised using scanning electron microscopy (SEM), including higher-magnification imaging of micropillar surfaces, while energy-dispersive X-ray spectroscopy confirmed the presence of silver. Higher-magnification SEM revealed nanoscale surface features on the micropillars, attributed to embedded or surface-associated silver nanoparticles. Antibacterial performance was evaluated using confocal laser scanning microscopy with live/dead staining. The PVDF-HFP/Ag films exhibited a significant reduction in bacterial viability, particularly against S. aureus (reducing viability to 0.6% ± 1.1%), while showing moderate activity against E. coli (41.0% ± 3.7% viability). While the fabricated micropillars (~5 µm) are larger than bacterial cells and unlikely to induce direct mechanical rupture, they increase surface interaction. To further investigate the theoretical antibacterial mechanism of scaled-down features, finite element analysis (FEA) was performed to model the mechanical interaction between bacterial cells and nanostructured pillars. The simulation results indicated localised stress concentrations that could compromise bacterial membrane integrity, suggesting a possible mechanobactericidal contribution if the microstructures are further reduced to the nanoscale, in addition to the primary biochemical effects of silver nanoparticles. FEA results do not aim to explain the experimentally observed antibacterial performance and should be interpreted only as a conceptual investigation. These findings demonstrate the potential of bio-inspired PVDF-HFP/Ag films as antibacterial materials for food packaging and related applications, subject to future comprehensive toxicity and quantitative microbiological evaluations. Full article

Conductive polymer composites with a segregated structure are a promising route to obtaining electrically active materials at low filler loadings. In this work, aminated graphene (AmG) was used as a functional conductive filler for the fabrication of composites with a segregated structure based on polyvinyl chloride (PVC) and poly(vinylidene fluoride-co-tetrafluoroethylene) (P(VDF-TFE)). AmG was comprehensively characterized by electron microscopy, core-level and near-edge spectroscopy, optical spectroscopy, and electrical measurements. The synthesized AmG contained 14.34 at.% nitrogen, with amines accounting for 81.44% of the nitrogen-related spectral intensity, corresponding to an amine concentration of 11.78 at.%. AmG also exhibited a restored π-conjugated network, intrinsic conductivity of 20–33 S/cm, and a crumpled-flake morphology favorable for interfacial contact with polymer particles. At a filler loading of only 1 wt.%, the segregated composites reached electrical conductivity up to 1.3–1.4 × 10⁻⁴ S/cm, exceeding those of the unfilled polymers by seven orders of magnitude. At 11 GHz, the AmG-filled P(VDF-TFE) composite showed 15.1 dB attenuation for a theoretical thickness of 30 mm, transmitting no more than 3% of the incident radiation. These results identify AmG as a functional conductive filler for segregated electrically conductive polymer composites and demonstrate that the combination of amine-containing surface chemistry, restored electrical conductivity, and crumpled morphology enables conductive interparticle network formation in PVC- and P(VDF-TFE)-based composites at only 1 wt.% filler loading. Full article

Limited ionic conductivity and unstable interfaces, primarily caused by poor solid–solid contact, pose significant challenges to the stable cycling of solid-state batteries. In this study, an interfacial in situ polymerization strategy is proposed to construct a poly(1,3-dioxolane) (PDOL) gel electrolyte layer between a poly(vinylidene fluoride) (PVDF)-based solid polymer electrolyte and the electrodes. This approach aims to address interfacial compatibility issues in solid-state lithium metal batteries. By precisely tuning the composition of the gel precursor and employing characterization techniques such as FTIR and NMR, the efficient ring-opening polymerization of 1,3-dioxolane (DOL) was confirmed, achieving a high conversion rate of 90%. The precursor was drop-cast onto the PVDF-based electrolyte/electrode interfaces before cell assembly. Electrochemical evaluations revealed that the in situ formed solidified interlayer significantly enhanced interfacial compatibility and ion transport, yielding a high Li⁺ transference number (0.341), an exceptional critical current density (1.4 mA cm⁻²), and remarkable cycling stability exceeding 1600 h in Li||Li symmetric cells. Furthermore, full cells incorporating LiFePO₄ cathodes demonstrated excellent rate capability and long-term cyclability, retaining 98.7% of their capacity after 1000 cycles. These results collectively underscore the effectiveness of this in situ solidification strategy in optimizing the interface structure and improving the overall performance of PVDF-based solid-state batteries. Full article

Efficient, low-cost catalysts are required for on-demand H₂ generation from chemical hydrides. This study utilized piezoelectric poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers (NFs) as a support to encapsulate bimetallic Co–Mo nanoparticles (NPs) for H₂ production via sodium borohydride (SBH) methanolysis. The PVDF-HFP membranes were synthesized through electrospinning, followed by in situ SBH reduction, which resulted in the uniform dispersion of amorphous Co–Mo NPs within the nanofibrous matrix. The optimized CoMo-0.2@PVDF-HFP membrane exhibited a hydrogen generation rate (HGR) of 1.9 × 10³ mL·min⁻¹·g⁻¹ (Co) at 298 K, indicating a 3.6-fold improvement relative to monometallic Co. Kinetic studies showed a nearly first-order relationship with catalyst dose and a nearly zero-order relationship with respect to SBH concentration, suggesting kinetics controlled by surface saturation. The activation energy (E_a) was determined to be 14.03 kJ·mol⁻¹. Moreover, the catalyst maintained over 80% of its original activity after five cycles. This enhanced performance is attributed to the combined effects of Co and Mo, the amorphous nature of the active sites, and the piezoelectric polarization of PVDF-HFP during mechanical stirring, which together improve charge transfer and reduce NP agglomeration. Full article

This study focuses on the development and characterization of advanced composite materials based on poly(ε-caprolactone) (PCL) and poly(vinylidene fluoride) (PVDF), with or without silver nanoparticles (AgNPs), planned for peripheral nerve or bone regeneration. The complementary properties of PCL (biocompatibility and biodegradability) and PVDF (mechanical stability and piezoelectric functionality) were exploited by blending the polymers in different ratios, resulting in binary (PCL/PVDF) and ternary (PCL/PVDF/AgNPs) composites. Green-synthesized AgNPs were integrated to enhance antimicrobial activity and to support tissue repair through improved signal transmission. Functional thin films and electrospun fibres were obtained and subjected to advanced characterization techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermal analysis. The results demonstrated appropriate morphology, chemical composition, structural stability, and favourable interactions with simulated physiological media. Preliminary biocompatibility assays confirmed good cell viability, supporting the biomedical applicability of the designed scaffolds. Overall, the obtained results highlight the potential of AgNPs-functionalized PCL/PVDF binary and ternary composites as promising candidates for flexible, durable, and bioactive implants in peripheral nerve or bone regeneration. Full article

The practical application of inorganic ferroelectric fillers in flexible piezoelectric composites is critically constrained by low polarization efficiency and severe interfacial incompatibility with polymer matrices. Herein, we report a multi-level in situ surface modification strategy that simultaneously addresses both limitations. High-purity one-dimensional tetragonal barium titanate nanofibers (BTO NFs) are first synthesized via sol–gel electrospinning combined with a two-step gradient annealing process, which precisely controls phase evolution and preserves structural continuity. To overcome the detrimental acid-induced degradation of BTO NFs during functionalization, a polydopamine (PDA) buffer layer is first conformally coated, followed by the liquid-phase deposition of a conductive polypyrrole (PPy) shell, forming a robust core–shell PPy@PBT NFs architecture. Incorporating only 4 wt% of these multifunctional fillers into a poly(vinylidene fluoride) (PVDF) matrix yields a dramatic enhancement in electromechanical performance. The resulting flexible piezoelectric energy harvesters achieve a piezoelectric coefficient (d₃₃) of 28.7 pC/N, an output voltage of 13 V, and an output current of 0.7 μA, representing substantial improvements over unmodified filler systems. This synergistic enhancement originates from the PDA-mediated interfacial stress transfer and the PPy-induced Maxwell–Wagner polarization intensification, establishing a robust and generalizable paradigm for high-performance flexible piezoelectric composites in self-powered wearable electronics. Full article

As a prospective two-dimensional conductive filler, titanium carbide (MXene) can remarkably boost the dielectric constant (ε) of polymer composites at low loadings. Nevertheless, the accompanied large dielectric loss (tan δ) and leakage current greatly limit their practical applications in dielectric-related fields. To tackle this dilemma, an organic polydopamine (PDA) shell was coated on an MXene surface via a self-polymerization method, and the dielectric properties of PDA-modified MXene/poly(vinylidene fluoride) (PVDF) were explored. The findings show that, in comparison to unmodified MXene/PVDF, MXene@PDA/PVDF retains a high ε and improved breakdown strength (E_b). It further realizes a notable decrease in both tan δ and electrical conductivity. The introduced PDA interlayer serves to effectively separate adjacent MXene nanosheets, which inhibits the development of conductive paths and introduces charge traps to restrict carrier migration, thus reducing tan δ. Further, the interlayer not only improves the interfacial compatibility, but also mitigates strong dielectric mismatch between MXene and PVDF, which facilitates the homogeneous redistribution of the local electric field, contributing to enhanced E_b. Theoretical fitting and simulation studies unlock the profound polarization mechanisms and charge migration modulated by the PDA interlayer. The resulting Mxene@PDA/PVDF exhibits concurrently elevated ε (35.68) and enhanced E_b (12.94 kV/mm), as well as low tan δ (0.34) at 10³ Hz and 7 wt% filler loading, which is not achievable in neat MXene/PVDF. This work demonstrates that core–shell interfacial engineering offers an effective strategy for designing flexible polymer dielectrics with superior dielectric performances, showcasing potential applications in energy storage, advanced power systems and flexible electronics. Full article

Graphene incorporation into polymer fibers offers a strategy to tune nanoscale morphology while preserving mechanical conformity for flexible composite applications. Graphene-based dopants can enable modulation of polymer fiber structure; however, the relationship between graphene incorporation, fiber morphology, and mechanical flexibility must be evaluated. This study investigates the integration of graphene oxide (GO) and reduced graphene oxide (RGO) into fibrous materials to tailor the structural and surface characteristics by fabricating GO- and RGO-enhanced poly(vinylidene fluoride) (PVDF) fibers via a wet-spinning process and examining the tunability of their morphology and its influence on mechanical properties. The effect of graphene doping and reduction state on fiber architecture is explored using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Brunauer–Emmett–Teller (BET) surface area analysis. Fourier transform infrared (FTIR) and Raman spectroscopy analyses confirmed the incorporation and reduction of graphene derivatives within the PVDF matrix while revealing corresponding changes in chemical functionality and the piezoelectric phase of PVDF. Mechanical flexibility is assessed through tensile testing, revealing increased stiffness with graphene addition, although maintaining sufficient structural integrity for wearable applications. These results collectively demonstrate that graphene doping provides a facile route to engineer composite fibers, enabling a balance between morphological complexity and mechanical compliancy, while establishing graphene-enhanced fibers as promising materials for flexible sensing systems and wearable smart textiles. Full article

Poly(vinylidene fluoride) (PVDF)-based ultrafiltration membranes play key roles in aqueous separation fields. However, the inherent hydrophobicity of PVDF always generates higher water permeation resistance and a greater fouling tendency in the filtration process. Different to the widely reported and widely used blending methods of increasing the hydrophilicity of PVDF membranes, the mass-produced hydrophilic PVDF copolymer is expected to be more efficient in producing high performance membranes. For this purpose, the present research offers a new and scalable approach to improving the hydrophilic properties of PVDF-based membranes through amphiphilic copolymers. Using 2-trifluoromethylacrylic acid (MAF) and hexafluoropropylene (HFP), carboxylated PVDF (PVHM) was synthesized following simple radical suspension copolymerization. Via a non-solvent-induced phase separation (NIPS) method, PVHM membranes were prepared and characterized. It was found that the PVHM membranes had enhanced hydrophilicity, permeability, fouling resistance, and alkali resistance compared with PVDF membranes. For the PVHM containing 8.3 wt% MAF, its membrane demonstrated superior static/dynamic fouling resistance to sodium alginate (FRR up to 99.1% for SA). Therefore, carboxylated PVDF polymers show potential for use in the industrial production of high-performance ultrafiltration membranes. Full article

Electrochromic devices have emerged as promising candidates for non-emissive displays due to their particular photoelectric performance in complex lighting environments. They exhibit considerable potential in emerging fields such as Internet of Things terminals, flexible wearables and human–computer interaction interfaces. In this study, we developed a low-power electrochromic display based on a Pt/FTO (Fluorine doped tin oxide) electrocatalytic counter electrode and a Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) porous gel electrolyte. The Pt catalyst enhances Br⁻/Br³⁻ redox reactivity, which reduces the driving voltage from 2 V to 1 V, and accelerates the electrode reaction kinetics. It is systematically explained by the Density Functional Theory (DFT) calculations and electrochemical characterization. Furthermore, we demonstrate a proof-of-concept multicolor display incorporating the electrocatalytic counter electrode with various viologen derivatives. This approach provides a significant advancement toward next-generation high-performance displays and is supportive of the development of energy-efficient optoelectronic devices. Full article

Bioelectricity plays a vital role in regulating cellular behavior. During the process of tissue repair and regeneration, surface electrical signals provided by biomaterials are found to be helpful. The characteristics of these electrical signals typically vary depending on the specific tissue repair requirements. In this study, zinc oxide nanorod (ZNR) arrays were loaded onto a poly(vinylidene fluoride-trifluoroethylene) (PVTF) substrate via the hydrothermal method. The nanorods were subsequently tilted by uniaxial stretching to form a ZNR/PVTF composite film with in-plane, horizontally aligned ZNRs along the stretching direction on the surface. The distribution of ZNRs created a heterogeneous potential across the PVTF substrate. Under ultraviolet (UV) irradiation, the surface potential of the ZNRs increased by approximately 76 mV due to a photoelectric response, enabling the formation of an adjustable millivolt-level surface potential. After corona polarization, the dipoles within the PVTF were aligned to achieve piezoelectric properties. The existence of oriented surface ZNRs enhanced the piezoelectric response of the ZNR/PVTF film, allowing for volt-level dynamic electrical signals through a force-voltage coupling mechanism. The output voltage increased from 1.32 V (PVTF) to 2.42 V (ZNR/PVTF) under the same 30° bending condition. Moreover, the ZNR/PVTF film exhibited excellent short-term biocompatibility toward bone marrow stem cells (BMSCs). Overall, this work presents an effective strategy for generating multiscale electrical signals through external field applications, demonstrating strong potential for tissue repair and regeneration. Full article

The increasing density of wireless and wearable electronic devices necessitates the development of lightweight, flexible, and absorption-dominated electromagnetic interference (EMI) shielding materials. In this study, electrospun poly(vinylidene fluoride) (PVDF) composite mats reinforced with carbon nanotubes (CNTs) and graphene nanosheets at low filler loadings (1–3 wt.%) were fabricated and systematically investigated for X-band (8.0–12.5 GHz) EMI shielding performance. Raman, FTIR, and thermal analyses confirm enhanced electroactive β-phase formation and improved thermal stability upon nanofiller incorporation. The formation of interconnected conductive networks within the electrospun fibrous architecture leads to a significant increase in electrical conductivity from 10⁻⁷ S·cm⁻¹ for pure PVDF to 10⁻² S·cm⁻¹ and 10⁻¹ S·cm⁻¹ for CNT/PVDF and Graphene/PVDF composites, respectively, at 3 wt.% loading. Consequently, the total EMI shielding effectiveness (SE_T) increases from 2.5 dB for pure PVDF to 40 dB for CNT/PVDF and 42 dB for graphene/PVDF composites at 3 wt.%. The shielding effectiveness arising from absorption (SE_A) dominates the overall EMI shielding performance, contributing more than 85% of the total shielding effectiveness (SE_T), which clearly indicates an absorption-controlled shielding mechanism. The combination of high absorption-dominated EMI shielding, low filler content, and mechanical flexibility highlights these electrospun CNT/PVDF and graphene/PVDF composites as promising candidates for next-generation flexible, wearable, and biomedical EMI shielding applications. Full article