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Engineered thiol anchored Au-BaTiO3/PVDF polymer nanocomposite as efficient dielectric for electronic applications
摘要： In modern electronic and electric appliances industries, polymer nanocomposites-based capacitors comprising of high dielectric constant ceramics (eg. BaTiO3 (BT), SrTiO3, CaCu3Ti4O12, etc.) and polymers (eg. polyvinyledene fluoride (PVDF), polyethylene terephthalate (PET), polycarbonate (PC), etc.) are becoming attractive for electrical energy storage applications. High dielectric constant fillers improve the energy density of the capacitors but at the cost of decreased efficiency, large dielectric loss as well as electrical conduction at high fields. In this paper, we present novel dielectric core-satellite BT-Au NPs for high energy density capacitor application. Hydroxylated barium titanate nanoparticles (BTO NPs) were immobilized with gold (Au) nanoparticles of size ~4 nm and were used as fillers into PVDF polymer matrix. The results show that the incorporation of Au on BaTiO3 nanoparticles improved the dielectric constant, energy density as well as efficiency, while reduction in the dielectric loss. To further improve the dielectric properties, Au-BTO NPs were coated with 2,3,4,5,6-Pentafluorothiophenol (PFTP) layer. The dielectric properties were further tuned with different PFTP concentrations. The PFTP serves as the bridge between nanoparticle and PVDF polymer by forming hydrogen bonding. The dielectric properties were measured at two different PFTP concentrations (PFTP1 and PFTP1.5, where 1 and 1.5 refers to the molar ratio of PFTP and Au decorated BaTiO3). The lower PFTP concentration results in improved dielectric properties, while increasing the concentration decreases the overall performance of the capacitors. The energy density of PFTP1@Au@BTO/PVDF was 2.04 J cm-3 at ~2100 kV cm-1 which was ~21% higher than that of PVDF and 70% higher than biaxially oriented polypropylene (BOPP), a present state-of-the art dielectric polymer. Thus, the combination of both, Au decoration on BT NPs and hydrogen bonding of PFTP with PVDF chains are responsible for improved dielectric properties and make these nanocomposites a promising candidate for energy storage applications.
关键词： Dielectrics,BaTiO3 nanoparticles,Polymer composites,Capacitors
更新于2025-11-14 17:28:48
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A conducting composite microfiber containing graphene/silver nanowires in an agarose matrix with fast humidity sensing ability
摘要： We report agarose-polymer-based composite microfibers with enhanced conductivity and fast humidity sensing owing to incorporation of conductive nanofillers. The microfibers are fabricated by extruding a hydrogel filament containing silver nanowires (AgNWs) and graphene oxide (GO, chemically reduced after extrusion) as 1D and 2D nanofillers, respectively. For the same concentration, GO enhances the mechanical properties of the microfibers more effectively than AgNWs. The microfiber with nanofillers has a higher Young’s modulus than commercial nylon-6 and polyamide. Due to synergy between AgNWs and reduced GO (rGO), the microfiber with both fillers shows higher conductivity than those with only one filler. The flexible microfiber retains its conductivity well under repeated bending/unbending cycles. Since rGO ionizes water molecules, the conductivity of the microfiber increases with increasing environmental humidity. Humidity sensing ability of the composite microfiber, based on the humidity-dependent conductivity, is demonstrated. The microfiber with both nanofillers respond rapidly and reversibly to humidity changes because the AgNWs facilitate charge carrier transport and water adsorption/desorption. The humidity sensor based on the composite microfiber also reliably detects repeated short human breaths.
关键词： Conducting microfibers,Polymer composites,Fast humidity sensing
更新于2025-09-23 15:22:29
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[IEEE 2018 Applications of Electromagnetics in Modern Techniques and Medicine (PTZE) - Rac?awice (2018.9.9-2018.9.12)] 2018 Applications of Electromagnetics in Modern Techniques and Medicine (PTZE) - Attenuation of High Frequency Electromagnetic Waves by Polymer Composites with Waste Materials
摘要： Composite materials with polymers and waste materials like zinc ore, mill scale, and iron dust are studied with respect to attenuation of electromagnetic radiation of high frequency. Samples of such composites were prepared and tested for several frequencies in 8-12 GHz band. The composites relatively strongly attenuate electromagnetic radiation in the considered band. Using various waste materials has also ecological aspect.
关键词： electromagnetic radiation,high frequency,attenuation,polymer composites,waste materials
更新于2025-09-23 15:22:29
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Photoemissive polymer composite based on new Y(III), Gd(III), and Tb(III) complexes with N-hydroxyphthalimide
摘要： In the present work, a green emitting composite with attractive photoluminescent properties was obtained through the embedding of the Tb 3+ complex with N-hydroxyphthalimide in a poly-(N-vinyl-pyrrolidone) matrix, which was further processed in thin or thick films. First, several complexes of Gd 3+ , Tb 3+ , and Y 3+ with N-hydroxyphthalimide with the general formula [M(NHF) 3 (DMF) 2 ] were prepared at a 1:3 metal/ligand ratio. The Tb 3+ complex presents specific emission peaks, with the most intense peak located at 543 nm, thus being selected for incorporation in the poly(N-vinyl-pyrrolidone) matrix. The prepared complexes and composites were investigated through elemental analysis, thermal analysis, FT-IR, P-XRD, and SEM. The photoluminescent properties were studied in detail. Remarkably, through the embedding in the poly(vinyl-pyrrolidone) matrix, the photoluminescent properties of the Tb 3+ complex are notably enhanced compared to the free complex.
关键词： Luminescent complexes,luminescent polymer composites,poly-(N-vinyl-pyrrolidone)
更新于2025-09-23 15:21:21
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Inorganic and Composite Fibers || Photocatalytic Properties of TiO2 Composite Nanofibers Electrospun With Different Polymers
摘要： Electrospinning offers the possibility to create fibers with very fine diameters. Spinning ultrafine fibers with diameters in the range of some hundred nanometers from melt or solution has been established some decades ago. With electrospinning, depending on the exact technology, either continuous fibers or fiber mats with relatively narrow diameter distributions can be created from a broad range of materials, starting from polymers to composites and even ceramics. Due to their large inner surface area, nanofiber mats are typically used as filter materials, catalyzers, medical wound dressing, or for promotion of cell growth in biomedical applications. Electrospinning ceramic nanofibers can be performed by co-spinning a blend of polymer and ceramic precursor, followed by calcination to remove the polymer matrix and keep only the ceramic fibers. Alternatively, ceramic nanoparticles can be bonded on the surfaces of polymer nanofibers, or hybrid nanofibers can be formed, consisting of ceramic and polymer materials. In this way, electrospinning can be used to produce a broad variety of nanofibers, besides other typical methods such as self-assembly, use of templates, or drawing, for applications in life sciences, energy storage, dye-sensitized solar cells (DSSCs), electronic and magnetic devices, bonding, etc.
关键词： TiO2 nanofibers,Electrospinning,photocatalytic properties,calcination,polymer composites
更新于2025-09-23 15:21:01
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The rapid and largea??scale production of carbon quantum dots and their integration with polymers
摘要： Carbon quantum dots (CDs) have inspired vast interests due to their prominent photoluminescence (PL) performances and promising applications in optoelectronic, biomedical and sensing fields. Notably, the development of effective approaches for large-scale CDs production may greatly promote the further advancement of their practical applications. In this review, the newly emerging methods for the large-scale production of CDs are summarized, such as microwave, ultrasonic, plasma, magnetic hyperthermia and microfluidic technology. Then, we introduce the available strategies for constructing CDs/polymer composites with intriguing solid-state PL. Particularly, the multiple roles of CDs are emphatically presented, including fillers, monomers and initiators. Moreover, the typical applications of CDs/polymer composites in light-emitting diodes, fluorescent printing and biomedicine are outlined. Finally, we discuss their current problems and speculate on their future development.
关键词： fluorescent materials,carbon dots,carbon dots/polymer composites,large-scale production
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Electrostrictive polymer composites based on liquid crystalline graphene for mechanical energy harvesting
摘要： High electromechanical coupling is critical to perform effective conversion between mechanical and electrical energy for various applications of electrostrictive polymers. Herein, a giant electrostriction effect is reported in liquid crystalline graphene doped dielectric elastomers. The materials are formulated by an original phase transfer method which allows the solubilization of graphenic monolayers in non-polar solvents. Dielectric spectroscopy is combined with tensile test devices to measure the true electrostriction coefficients with differentiating the Maxwell stress effect. Because of their unique liquid crystal structure, the resultant composites show a giant relative permittivity and ultralarge electrostriction coefficient. This work offers a promising pathway to design novel high performance electrostrictive polymer composites as well as to provide insights into mechanisms of true electrostriction in electrically heterogeneous systems.
关键词： polymer composites,electrostriction,graphene
更新于2025-09-23 15:21:01
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Self-assembled electrodes based on polyaniline grafted with reduced graphene oxide and polystyrene sulfonate
摘要： In this work, composites based on polyaniline (PAni) grafted with reduced graphene oxide (rGO) were obtained by the in situ chemical polymerization of aniline with rGO (mass ratio of 1 and 2.5%) dispersed into the monomer solutions. PAni and its PAni-rGO composites were used to prepare self-assembled (SA) films by depositing them onto indium tin oxide (ITO) substrates with alternating layers of polystyrene sulfonate (PSS). The structure and morphology of the materials were characterized by Fourier-transform infrared spectroscopy (FT-IR), RAMAN spectroscopy, and scanning electron microscopy (SEM). The oxidation states of PAni and its PAni-rGO composites were characterized by cyclic voltammetry (CV) and UV-Vis spectroscopy during the SA procedure. The electrochemical behavior of the obtained SA films was also characterized by electrochemical impedance spectroscopy (EIS). The EIS results showed a significant decrease in the polarization resistance (Rp), from 1020 to 302 Ω, for the film with 1% of rGO (PAni-1%rGO/PSS) when compared with its unmodified counterpart (PAni/PSS). The synergic effects observed for the PAni-1%rGO/PSS film showed that controlling the rGO mass ratio plays an important role in the improvement of the charge transfer processes, and that this electrode has potential for electrochemical applications, such as sensors and charge storage devices.
关键词： Conducting polymer composites,Polyaniline,Reduced graphene oxide,Self-assembly
更新于2025-09-23 15:19:57
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Laser Optoacoustic Method for Quantitative Porosity Assessment of Carbon Fiber Reinforced Plastic Composites Based on Acoustic Impedance Measurement
摘要： A method for measuring the acoustic impedance for the assessment of the porosity of carbon fiber reinforced plastic composites using laser thermo-optical excitation of longitudinal acoustic waves is proposed and experimentally realized. The acoustic impedance of the test sample is measured from the magnitude of the antiderivative ultrasonic pulse reflected from the immersion liquid–sample interface. A method for calculating the porosity of carbon fiber plastic composites based on the measured acoustic impedance is presented. Composite samples with three different carbon fiber layers stacking schemes were investigated. It is shown that in the studied composites, the local porosity distribution is nonuniform along the fiber stacking plane. The porosity value, averaged from optoacoustic measurement results, actually coincides with X-ray tomography data within the error limits. The presented method for determining porosity does not require determining the volume and mass of the studied object and can be used for investigation of composite structures with complex shapes.
关键词： porosity,laser optoacoustic method,polymer composites,longitudinal acoustic waves
更新于2025-09-23 15:19:57
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Robust Polymer Matrix Based on Isobutylene (Co)Polymers for Efficient Encapsulation of Colloidal Semiconductor Nanocrystals
摘要： We introduce new oxygen- and moisture-proof polymer matrices based on polyisobutylene (PIB) and its block copolymer with styrene (poly(styrene-block-isobutylene-block-styrene), PSt-b-PIB-b-PSt) for encapsulation of colloidal semiconductor nanocrystals. In order to prepare transparent and processable composites, we developed a special procedure of the nanocrystal surface engineering including ligand exchange of parental organic ligands to inorganic species followed by attachment of specially designed short-chain PIB functionalized with amino-group (PIB-NH2). The latter provides excellent compatibility of the particles with the polymer matrices. As colloidal nanocrystals, we chose CdSe nanoplatelets (NPLs), since they possess a large surface and thus are very sensitive to the environment, in particular in terms of their limited photostability. The encapsulation strategy is quite general and can be applied to a wide variety of semiconductor nanocrystals, as demonstrated on the example of PbS quantum dots. All obtained composites exhibited excellent photostability being tested in a focus of a powerful white-light source, as well as exceptional chemical stability in a strongly acidic media. We compared these properties of the new composites with those of widely used polyacrylate based materials, demonstrating the superiority of the former. The developed composites are of particular interest for application in optoelectronic devices, such as color-conversion light emitting diodes (LEDs), laser diodes, luminescent solar concentrators, etc.
关键词： photoluminescence,nanocrystals-in-polymer composites,lead sulfide quantum dots,semiconductor nanocrystals,isobutylene (co)polymers,cadmium selenide nanoplatelets,photostability,chemical stability
更新于2025-09-19 17:15:36