PVDF Matrix Research Articles

Ultrahigh energy density in dielectric nanocomposites by modulating nanofiller orientation and polymer crystallization behavior

High-energy density dielectrics for electrostatic capacitors are in urgent demand for advanced electronics and electrical power systems. Poly(vinylidene fluoride) (PVDF) based nanocomposites have attracted remarkable attention by intrinsic high polarization, flexibility, low density, and outstanding processability. However, it is still challenging to achieve significant improvement in energy density due to the common contradictions between electric polarization and breakdown strength. Here, we proposed a novel facile strategy that simultaneously achieves the construction of in-plane oriented BaTiO3 nanowires and crystallization modulation of PVDF matrix via an in-situ uniaxial stretch process. The polar phase transition and enhanced Young's modulus facilitate the synergetic improvement of electric polarization and voltage endurance capability for PVDF matrix. Additionally, the aligned distribution of nanowires could reduce the contact probability of nanowire tips, thus alleviating electric field concentration and hindering the conductive path. Finally, a record high energy density of 38.3 ​J/cm3 and 40.9 ​J/cm3 are achieved for single layer and optimized sandwich-structured nanocomposite, respectively. This work provides a unique structural design and universal method for dielectric nanocomposites with ultrahigh energy density, which presents a promising prospect of practical application for modern energy storage systems.

Improved properties of CoFe2O4@rGO/PVDF composites prepared through a solution-mixing approach

In this work, a hybrid material based on CoFe2O4 nanoparticles immobilized on reduced graphene oxide (CoFe2O4@rGO) was successfully synthesized through a one-step green solvothermal method. Subsequently, the resultant CoFe2O4@rGO was further modified by aminopropyltriethoxysilane to form the A-CoFe2O4@rGO hybrid, serving as the filler of poly(vinylidene fluoride) (PVDF). The facile preparation of A-CoFe2O4@rGO was confirmed through various microstructural characterization techniques. PVDF-based composites with varying contents of A-CoFe2O4@rGO (1 wt%, 3 wt%, 5 wt%, 7 wt%, and 10 wt%) were prepared using a solution-mixing approach. SEM results revealed uniform distribution of the A-CoFe2O4@rGO filler within the PVDF matrix. The XPS results indicated an obvious interfacial interaction between the A-CoFe2O4@rGO filler and PVDF matrix. Consequently, the crystallization degree and β crystalline content of PVDF matrix in the A-CoFe2O4@rGO(7 wt%)/PVDF composite were enhanced to 52.3 % and 32.1 %, respectively, compared to 42.2 % and 26.0 %, respectively, in pure PVDF. The A-CoFe2O4@rGO(10 wt%)/PVDF composite enhanced electrical conductivity and dielectric constant at 100 Hz, with values of 1.33 × 10−7 S/m and 22.1, respectively, compared to 1.86 × 10−9 S/m and 8.6, respectively, in pure PVDF. In addition, despite the non-magnetic nature of pure PVDF, the A-CoFe2O4@rGO(10 wt%)/PVDF composite possessed a magnetization value of 1.64 emu/g at 60,000 Oe. The comprehensive enhancement in crystallization behavior, electrical, dielectric, and magnetic properties demonstrates the potential of the A-CoFe2O4@rGO/PVDF composite for various applications.

Electromagnetic interference shielding and DFT study of barium hexaferrites nanoparticles coated polyaniline with heterointerface polarization behavior

Barium-hexaferrite-nanoparticles (BHNs) and polyaniline-nanoparticles (PNs) were prepared individually with average particle sizes of 50 nm and 42 nm. The two nanoparticles were then combined to create hybrid nanoparticles (HNs) with a ferritic core and a conductive surface, by chemically coating polyaniline onto the surface of BHNs via in-situ polymerization. The nanoparticle shape, size, structural, and morphological properties were analyzed using SEM, XRD, and PSA. The nanoparticles were dispersed into a PVDF matrix to produce nanocomposite-films (NFs) for testing EMI shielding effectiveness. The NFs exhibited excellent blocking of near infrared radiation and a shielding effectiveness of more than 50 dB in the microwave region when 30 wt% of HNs was used in the PVDF matrix. Density-function-theory (DFT) based on first-principle was used to confirm the interfacial polarization contribution at the heterointerface, revealing different electron occupied states and considerable charge transfer and accumulation at the interface, enhancing the EMI shielding effectiveness.

PVDF-Halloysite-Ceria multifunctional membrane for one-step treatment to industrial effluent

Industrial wastewater, containing diverse pollutants like dyes and oils, poses detrimental environmental challenges. Membrane technology addresses this complexity well but requires tailored nanofiller modifications that enhance hydrophilicity, oleophobicity, and antifouling potential for efficient separation. In this context, our work focuses on the development of mixed matrix membranes (PV-H-C) – PVDF, halloysite nanotubes (HNTs), and ceria nanoparticles – for effective dye and oil-water emulsion separation, enabling high flux recovery. The tubular structure of HNTs, with a lumen, enables the encapsulation and controlled distribution of ceria nanoparticles, preventing their agglomeration and leading to more uniform dispersion within the membrane matrix. HNTs porous structure, high surface area, and numerous adsorption sites within its nanotubes excel in rapid dye adsorption and ceria’s inherent hydrophobic properties along with low surface energy, forms a barrier against oil adhesion and spreading. Optimal results were achieved by loading 2% HNT and 1% ceria in the PVDF matrix, ensuring improved membrane performance. HNTs enhanced hydrophilicity and achieved pure water permeate flux of 1698 L/m2.h.bar. Developed membranes are super-oleophobic with an underwater contact angle of 132° + 3° and show a 100% increase in dyes and oils separation efficiency as compared to the pristine PVDF membranes. This unique integration of ceria with halloysite nanotubes in PV-H-C membranes is pivotal, bestowing exceptional anti-fouling characteristics and reusability, while providing a one-step, comprehensive solution for the effective treatment of complex industrial wastewater that encompasses both oil and complex dyes.

A bifunctional double-layer Fe3O4-Polyvinylidene fluoride(PVDF)/PVDF separator with enhanced thermal stability for Li-S batteries

Li-S batteries, utilizing sulfur as the active material, have garnered significant attention due to their impressive theoretical specific capacity of 1675 mA h g−1. However, the commercialization of these batteries faces challenges primarily stemming from the volume expansion of sulfur and the shuttling effect caused by soluble polysulfides. In this study, we present a novel solution through the development of a bifunctional double-layer Fe3O4-PVDF/PVDF separator via electrospinning. The mesh structure of PVDF facilitates rapid lithium ion transport and effectively accommodates the volume expansion of sulfur during discharge/charge, leveraging its high thermal stability and mechanical properties. The incorporation of Fe3O4 within the PVDF matrix serves to trap polysulfides, mitigating the shuttle effect. Experimental results demonstrate that Li-S batteries employing the Fe3O4-PVDF/PVDF separator exhibit an initial discharge capacity of 1052.7 mA h g−1 at a current density of 0.5 C, with a commendably low capacity decay rate of 0.08 % per cycle after 250 cycles. This innovative separator design showcases promising advancements in addressing critical issues hindering the commercial viability of Li-S batteries.

On the geometry and material stability of tubular PVDF-TiO2 static mixer membrane contactors for photocatalytic ozonation of micropollutants

The prevention of ozone hotspots in ozonation reactors for wastewater treatment is essential for effective degradation of micropollutants without forming harmful by-products. Membrane contactors can provide a bubble-free ozonation process that is able to decrease by-product formation, e.g., bromate formation in bromide-charged wastewater. Furthermore, the geometry of the reactor influences the distribution of dissolved ozone in a membrane contactor. Turbulence promoters can significantly decrease ozone hotspots and increase ozone mass transfer into wastewater. This work presents a fabrication methodology to produce PVDF-TiO2 helical static mixer membranes using the rotation-in-a-spinneret technology. Static mixer membranes combine the functionality of a membrane contactor and a static mixer in a single component. Furthermore, the PVDF matrix is doped with TiO2 particles as photocatalyst. Thus, we present a membrane-based photocatalytic ozonation process to increase the concentration of hydroxyl radicals for degradation of micropollutants under UV radiation. Static mixer membranes increase the ozone mass transfer coefficient by 70% compared to conventional hollow fiber membranes. Furthermore, the specific photocatalytic degradation rate of methylene blue increases by 50% using static mixer membranes. However, this work also reveals a lack of long-term stability of PVDF-TiO2 membranes in the corrosive environment of photocatalytic ozonation. The molecular weight of PVDF decreases by 11% after use in photocatalytic ozonation resulting in a loss of mechanical stability of the membranes. Similar material concepts are required based on ceramic materials which avoid wetting of the porosity.

Multiple Na+ transport pathways and interfacial compatibility enable high-capacity, room-temperature quasi-solid sodium batteries

Sodium-metal batteries (SMBs) are ideal for large-scale energy storage due to their stable operation and high capacity. However, they have safety issues caused by severe dendrite growth and side reactions, particularly when using liquid electrolytes. Therefore, it is critically important to develop electrolytes with high ionic conductivity and improved safety that are non-flammable and resistant to dendrites. Here, we developed polymerized polyethylene glycol diacrylate (PEGDA)-modified poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) electrolytes (PPEs) with highly conductive sodium bis(trifluoromethanesulfonyl)imide and corrosion-inhibitive sodium bis(oxalato)borate salts for SMBs. Well-complexed PEGDA not only increases the amorphicity of the PVDF matrix, but also offers numerous Lewis basic sites through the polar groups of carbonyl and ether groups (i.e., electron donors). The presence of the Lewis basic sites facilitates the dissociation of sodium salt and transportation of Na+ within the PVDF matrix. This results in the generation of additional Na+ transport pathways, which can enhance the performance of the battery. Among PPEs, the optimized PPE-50 exhibits a high ionic conductivity of 3.42 × 10–4 S cm−1 and a mechanical strength of 14.0 MPa. A Na||Na symmetric cell with PPE-50 displays high stability at 0.2 mA cm−2 for 800 h. PPE-50 further displays high capacity, e.g., a Na3V2(PO4)3|PPE-50|Na battery delivers a decent discharge capacity of 101.5 mAh g−1 at 1.0C after 650 cycles. Our work demonstrates the development of high-performance quasi-solid polymer electrolytes with multiple transport pathways suitable for room-temperature SMBs.

Enhanced Dielectric and Electric Properties of ZnFe2O4‐Poly(Vinylidene Fluoride) Composites by Employing Surface Hydroxylated ZnFe2O4 Nanoparticles

AbstractA facile solvent casting technique has been reported in the fabrication of surface hydroxylated ZnFe2O4 (h‐ZFO) nanoparticles (NPs) filled with poly(vinylidene fluoride) (PVDF) as a matrix. The h‐ZFO filler particles are synthesized from neat ZnFe2O4. The dielectric and electric performance of polymer‐based composites is much related to the interface binding between filler particles and polymer matrix. In this work, the surface alternation technique employed a new path is developed to improve the compatibility between ZFO particles and the PVDF matrix. These PVDF‐ZFO composites were studied by X‐ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The h‐ZFO‐PVDF and ZFO‐PVDF composites are carefully analyzed by dielectric and electric properties by a wide range of frequencies. However, the morphological analysis exhibits uniform dispersion of the h‐ZFO NPs in the PVDF matrix. The h‐ZFO‐PVDF composites have a dielectric constant of about 35 for 1.5 wt.% of filler contents. Moreover, the h‐ZFO‐PVDF composites have lower dielectric loss than PVDF‐ZFO composites. It is suggested that the strong interaction between h‐ZFO filler particles and the PVDF matrix is the main reason for the improvement of dielectric properties. The outcomes of these methods have great potential for making high dielectric constants and relatively suppressed loss PVDF‐ZFO composites for advanced practical applications.

Development of flexible PVDF/ BaTiO3-MoS2 polymer nanocomposites for energy harvesting and gas sensing applications

The need for flexible and wearable devices is quite great in the modern era of advanced electronics and the Internet of Things (IoT). Here, we present a poly(vinylidene fluoride) (PVDF)/Barium Titanate–Molybdenum Disulfide (BaTiO3–MoS2) composite-based flexible piezoelectric nanogenerator (PENG) with an improved electroactive phase. The electroactive, β-phase of the PVDF is shown to increase with the addition of BaTiO3–MoS2 fillers as a result of the filler’s good interfacial interaction with the polymer matrix. The improved electroactive phase in the PVDF matrix was confirmed by the X-ray diffraction method and FTIR analysis of the composite films. The uniform dispersion of filler particles in the polymer matrix was confirmed by a scanning electron microscopy analysis. The developed piezoelectric nanogenerator device generated peak-to-peak output voltage of 4.9 V with a high dielectric constant of 22 and a low dielectric loss of 4.7. The fabricated gas sensor can perform at room temperature and exhibits good gas sensing performance toward the NH3 gas. It was found that, compared to all other samples, the composite PVDF/BaTiO3–MoS2 films had a high level of sensitivity. Additionally, the composite films showed response and recovery times of 11 and 17 s. The composite based on PVDF/BaTiO3–MoS2 is a suitable material for NH3 sensor applications.

Preparation of Three Component PVDF‐Bi4V2O11‐SDS Composites with Enhanced Dielectric and Electrical Properties

AbstractIn this work, poly(vinylidene fluoride) (PVDF)‐bismuth vanadate (Bi4V2O11; BVO)‐sodium dodecyl sulfate (SDS) composite films are fabricated by the solution casting method. The frequency dependence of the dielectric and electric performances of the resultant PVDF‐BVO‐SDS composites on various weight percentages of SDS contents is investigated. The results demonstrate that the three‐component PVDF‐BVO‐SDS composites have a superior dielectric constant (96) and suppressed dielectric loss (<1) at 102 Hz for 20 wt% of SDS contents. The surface morphology of the PVDF‐BVO‐SDS composites shows that SDS is successfully reinforced on the PVDF‐BVO matrix with better homogeneity. The ac conductivity of the PVDF‐BVO‐SDS composites is also improved, which is helpful for the enhancement of the dielectric constant and relatively low loss in the composites. Moreover, the PVDF‐BVO‐SDS composite also exhibits a larger value of the dielectric constant (96) than the pristine PVDF matrix, which is 15 times higher than that of the pristine one. These significantly enhanced dielectric and electrical characteristics of PVDF‐BVO‐SDS composites will fulfill the practical criteria for their use in high dielectric‐constant capacitors and energy storage devices.

An effective microwave absorber using multi-layer Design of carbon allotrope based Co2Z hexaferrite-Polymer nanocomposite film for EMI shielding applications

This report shows impressive electromagnetic interference (EMI) shielding efficiency of laminated nanocomposites of PVDF containing binary nanofillers of rGO and Co2Z hexaferrite. These rGO layers in the PVDF matrix in association with magnetic nanofillers have been considered to improve interfacial polarization by accumulating charges at the interfaces of rGO-Co2Z hexaferrite-PVDF system. The crystallographic phase, chemical composition, and successful incorporation of the binary nanofillers into PVDF have been verified using XRD, XPS, RAMAN, and FESEM analysis. The J-E analysis of rGO-Co2Z hexaferrite-PVDF nanocomposite films confirm that the current density of all the nanocomposite films is very less and found in the order of 10-5 A/m2 under the maximum electric field of 70 kV/m. This indicates the emergence of polarization effect in the nanocomposite films when subjected to high external electric field without having electrical breakdown. The significant magnetization of ∼8.9 emu/g for nanocomposite films, at room temperature is beneficial for boosting the EMI shielding effectiveness due to absorption (SEA). The combination of magnetization and electrical polarization in nanocomposite film helps to attain significantly high total shielding effectiveness (SET) in the frequency range of 12–18 GHz. The shielding effectiveness study of both mono-layer and multi-layer nanocomposite films have been investigated. Improvement of SEA has also been achieved by the elevation of the thickness of the nanocomposite film within the range of 0.8 to 1.0 mm, which in turn improves SET to a value of −54.09 dB at 15.70 GHz for multi-layer system of thickness 0.861 mm with >99.999 % of attenuation whereas the mono-layer film of thickness 0.180 mm shows the SET of −47.03 dB at 14.76 GHz with an attenuation of >99.99 %.

Notably enhanced dielectric response with low loss in PVDF composites filled with RuO2–BaTiO3 hybrid particles

This study delineates the process of fabricating and the results of investigating the dielectric properties of hybrid particles created through the integration of Poly(vinylidene fluoride) (PVDF) filled with RuO2 coated on BaTiO3 nanoparticles (nBT), designated as RuO2–nBT. These hybrid particles were successfully synthesized employing a simple and cost–effective solid–state reaction method. The inclusion of RuO2–nBT in the PVDF matrix engendered a notable enhancement in its dielectric properties. Notably, a RuO2–nBT fraction of 0.5 manifested a dielectric constant (ε′) of 107.4 and a dielectric loss tangent (tanδ) value of 0.062 at 30 °C and 1 kHz. These findings signify the effective role of interfacial polarization occurring between the PVDF matrix and the RuO2–nBT hybrid particles, leading to a marked improvement in dielectric attributes. Moreover, the observed low tanδ value indicates the elimination of conductive pathways, an inhibitory effect attributed to the incorporation of RuO2–nBT hybrid particles. This study underscores the promising potential of RuO2–nBT hybrid particles in fine–tuning and augmenting the dielectric properties of polymer composites, particularly in scenarios necessitating low tanδ and high ε′ values.

Tunable Dielectric Spectroscopy of PVDF Thin Films Crossbred with TiO2 Nanoparticles for the Storage Devices

AbstractPolyvinylidenefluoride (PVDF) is a semi‐crystalline ferroelectric polymer with a wide range of interesting properties and shows potentiality in a variety of technological applications. Flexible thin films of PVDF nanocomposites (NCs) have attracted many researchers due to their tunable electronic properties. This paper reports the synthesis, characterization, and dielectric studies of PVDF‐TiO2 NC thin films. The synthesized films are self‐supporting thin and the average thickness of the thin films is 60 µm measured using a Digital thickness gauge of resolution 0.01 mm. TiO2 nanoparticles are prepared using the combustion method. Commercially available PVDF granules are used to develop PVDF‐TiO2 NC thin films using the film casting technique. The structural study of the prepared thin films is carried out using XRD that confirms the retention of the β‐phase of PVDF. The functional group and bonding nature have been studied using FTIR Spectroscopy. The thermal stability of the NC thin films is studied using TGA. The variation of dielectric constant (DC), dielectric loss (DL), AC conductivity, and dissipation factor of the medium of pristine PVDF and PVDF‐TiO2 NC thin films are studied in the frequency range of 10 Hz to 8 MHz at ambient temperature. The dielectric constant of PVDF‐TiO2 NC thin films increases up to 8 wt% and anomaly for 10 wt% of TiO2 fillers in the PVDF matrix at a lower frequency and found to decrease with increasing frequency. The dielectric loss of NC thin films is high at a lower frequency and decreases with an increase in the frequency that is in good agreement with the Maxwell–Wagner type of interfacial polarization. At lower frequencies, the dielectric constant of PVDF‐TiO2 NC increases with the increase in filler content. AC conductivity shows a sharp increase at higher frequencies whereas the dissipation factor of the polymer NCs remains unaltered with respect to frequency by maintaining the trend. This suggests that PVDF‐TiO2 NC is potential material for energy storage devices.

Synergistic effect of nano-BaTiO3 and montmorillonite nanoclay on the AC conductivity and dielectric properties of poly(vinylidenefluoride) nanocomposite films

Poly(vinylidene fluoride) (PVDF), Barium Titanate (BaTiO3) and Montmorillonite (MMT) nanoclay based polymer nanocomposite (PNCs) were synthesized using a solution casting technique by encapsulating various loadings of BaTiO3 and MMT in PVDF matrix. The completely dispersed and highly flexible PVDF/BaTiO3/MMT nanocomposite films which were subjected to different characterization studies. The structural and morphological analysis of the synthesized nanocomposite films has been done using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). BaTiO3 and MMT reinforcement in the polymer matrix results in structural modifications of the PNCs. Thermogravimetric analysis (TGA) were employed to assess the thermal characteristics of PVDF/BaTiO3/MMT PNCs. The dielectric properties such as dielectric constant (ϵ), dielectric loss (tan δ), and AC conductivity (σac) of nanocomposite films were also examined as functions of frequency (50 Hz to 10 MHz) and temperature (30 °C to 150 °C). The highest ϵ was obtained at low frequency at higher temperatures for all the nanocomposite films. These findings imply that the PVDF/BaTiO3/MMT nanocomposites can be an effective material for energy storage applications.

Influence of Nano-CeO2 and Graphene Nanoplatelets on the Conductivity and Dielectric Properties of Poly(vinylidene fluoride) Nanocomposite Films.

Novel three-phase polymer nanocomposites (PNCs) based on cerium oxide (CeO2) nanoparticles (NPs) and graphene nanoplatelets (GNPs) incorporated in a poly(vinylidene fluoride) (PVDF) matrix were formulated using a solution-casting approach. To understand the structural and morphological features of PVDF/CeO2/GNP nanocomposites (NCs), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses were accomplished. The PVDF/CeO2/GNP NCs displayed improved thermal stability which resulted from strong bonding between GNPs and CeO2 NPs and restriction of the polymer chain movement. The introduction of CeO2 NPs and GNPs within the PVDF matrix and good synergy between CeO2 NPs and GNPs led to variable mechanical properties of the prepared NCs. The PVDF/CeO2/GNP NCs portrayed reduced thermal stability, which could be due to the increased mobility of PVDF chains imposed by GNPs leading to the formation of volatile degradation products. Moreover, PVDF/CeO2/GNP NCs exhibited good electrical conductivity and high dielectric permittivity. The obtained dielectric permittivity value for the PVDF/CeO2/GNP NCs was 3-fold greater than PVDF/CeO2 NCs, making these novel tertiary composite materials a probable candidate for energy-storage applications.

Efficient energy harvesting enabled by large-area piezoelectric PVDF-based composite film enhanced by carbon nanotubes

Considerable attention has been drawn to the use of flexible piezoelectric energy harvesting devices for powering smart wearable technology. Herein, we employed a melt extrusion casting process to prepare large-area PVDF-based piezoelectric composite films and achieved continuous production. The films were prepared by adding 15 wt% lead zirconate titanate powder modified with a titanium coupling agent (PZT@UP15) and different content of carbon nanotubes (CNTs) exhibiting high conductivity into the PVDF matrix. The addition of CNTs in moderate amounts significantly enhanced the mechanical, dielectric, and piezoelectric properties of the composite films. Remarkably, the composite film containing 0.06 wt% CNTs achieved a d33 value of 28 pC/N, generated an open circuit voltage of 16.85 V, and a maximum power density of 0.46 μW/cm2 in the bending-releasing mode. Furthermore, the film exhibited relatively stable output performance even after 1500 cycles. The enhanced performances of the piezoelectric composite films can be attributed to the factors that the CNTs can effectively promote PVDF polarization by inducing dipole alignment and building an internal electric field, and further improve the piezoelectric performance and the electrostrictive performance. This work shows that the prepared piezoelectric composite film holds great potential as an energy harvesting device to provide power for wearable electronic devices.

Piezoelectric thin Film Composites with BaTiO3 for Microelectronics

The piezocomposites from poly-(vinylidene fluoride) (PVDF) with BaTiO3 (BT) are largely presented in literature, but the composites from polydimethylsiloxane (PDMS) with BT consist a very new scientific preoccupation. The novelty of the paper lies in a new simpler route of preparation of the two composites with PDMS and respectively PVDF matrix, with tailored deposition on specific substrates for microelectronic use (e.g. indium-tin-oxide ITO/glass, Si/Pt, polyethylene terephthalate PET), along with an extensive comparation of their dielectric features, a consistent comparison of the influence of polymer matrix upon the piezoelectric features, and a demonstration of direct use for microelectronic applications of the composites of BT with PDMS. An interesting effect is observed around 100 kHz domain, determined by the activity and architecture of BT particles mainly for the BT-PDMS composites, which induce an additional ionic-dipolar conjugated polarization, as a displacement due to the balance between the resonance and anti-resonance frequency. Such phenomena explain the potential use of such composites as resonators/filters, and BT-PDMS composites should be further investigated for tailored applications in radiofrequency electronic field. We can appreciate that superior piezoelectric features are offered by the composites of BT with PDMS, comparing to the composites with PVDF, which means that the composites of BT with PDMS were worth to study, leading to more versatile variants of electronic characteristics and with superior values.

In situ preparation of highly luminescent Sb3+/Mn2+ co-doped Cs2KInCl6 lead-free double perovskites in a PVDF matrix and application to white light emitting diodes and anti-counterfeiting

A strategy for in situ preparation of lead-free double perovskite-based polymer composite film with large area and high efficiency white light emission and its applications.

Exploring the material and dielectric properties of poly(vinylidene fluoride) composites incorporated with graphene and graphene oxide.

This study focuses on enhancing the structural, thermal, and dielectric properties of poly(vinylidene fluoride) (PVDF) nanocomposites loaded with graphene oxide (GO) and graphene (G), synthesized via solution casting. Characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA), revealed significant enhancements due to the nanofillers. The crystallinity of PG composites increased to 60.39% from 49.21% in neat PVDF, transitioning from α to β phases, which is beneficial for high-performance electronics and energy storage. PG composites showed a dielectric constant (ε') of 10.50, higher than those of neat PVDF (ε' = 7.54) and PGO composites (ε' = 8.56). The dielectric loss (tan δ) for PG was low at 0.15, suitable for electronics. The AC conductivity of PG composites (2.22 × 10-7 S cm-1) was higher than those of neat PVDF (1.09 × 10-7 S cm-1) and PGO (1.65 × 10-7 S cm-1), enhancing their suitability for flexible electronics. Thermal stability assessments showed that PG composites had the highest degradation temperature at 471.04 °C, indicating improved thermal resistance. These enhancements are due to the effective dispersion and interaction of graphene-based nanofillers within the PVDF matrix. This study demonstrates that incorporating nanofillers into polymer composites significantly advances materials science by enhancing the dielectric properties for various industrial applications.

Investigation on the properties of PVDF matrix composite porous gel polymer electrolyte doped with lithium silicon gel

Gel polymer electrolytes are safer because they do not contain liquid phase components. On this basis, the introduction of inorganic fillers effectively overcame the problem of low ionic conductivity of polymer electrolyte at room temperature, and the constructed composite polymer electrolyte (CPEs) combined the advantages of inorganic fillers and polymer segments. In this paper, lithium silicon gel SiO2(Li+) was prepared by in-situ polymerization and sol-gel method, and doped in PVDF composite porous gel polymer electrolyte film prepared by immersion precipitation method. The electrochemical properties and surface topography of lithium iron phosphate were investigated by mounting a bonded lithium iron phosphate quasisolid lithium-ion battery. The experimental results show that the solid electrolyte film modified by SiO2(Li+) has good electrochemical and a certain reference value.