Molecular Interaction Mechanisms Between Lubricant-Infused Slippery Surfaces and Mussel-Inspired Polydopamine Adhesive and DOPA Moiety

Lubricant-infused slippery surfaces have recently emerged as promising antifouling coatings, showing potential against proteins, cells, and marine mussels. However, a comprehensive understanding of the molecular binding behaviors and interaction strength of foulants to these surfaces is lacking. In this work, mussel-inspired chemistry based on catechol-containing chemicals including 3,4-dihydroxyphenylalanine (DOPA) and polydopamine (PDA) is employed to investigate the antifouling performance and repellence mechanisms of fluorinated-based slippery surface, and the correlated interaction mechanisms are probed using atomic force microscopy (AFM). Intermolecular force measurements and deposition experiments between PDA and the surface reveal the ability of lubricant film to inhibit the contact of PDA particles with the substrate. Moreover, the binding mechanisms and bond dissociation energy between a single DOPA moiety and the lubricant-infused slippery surface are quantitatively investigated employing single-molecule force spectroscopy based on AFM (SM-AFM), which reveal that the infused lubricant layer can remarkably influence the dissociation forces and weaken the binding strength between DOPA and underneath per-fluorinated monolayer surface. This work provides new nanomechanical insights into the fundamental antifouling mechanisms of the lubricant-infused slippery surfaces against mussel-derived adhesive chemicals, with important implications for the design of lubricant-infused materials and other novel antifouling platforms for various bioengineering and engineering applications.

Memory effect in ferroelectric polyvinylidene fluoride (PVDF) films via spin crossover probes

Ferroelectric polymers are of great interest due to their intrinsic processing capabilities, superior to classic inorganic ferroelectric materials. For example, polyvinylidene fluoride (PVDF) and derivatives have been incorporated into multiple device architectures for information storage and transfer. Here we report an additional advantage of organic ferroelectrics as their flexibility allows for the preparation of composites with spin crossover (SCO) probes to tune their ferroelectric parameters by external stimuli. We demonstrate how the saturation polarization and coercive field of a ferroelectric [Fe(NH2trz)3](NO3)2/PVDF composite film depends on the spin state of the [Fe(NH2trz)3](NO3)2, opening a thermal hysteresis and delivering a ferroelectric material with a memory effect. This switching may now be used to tune the function of a device, adding additional information states to the elemental binary logic. Additional evidence of the synergy between the two components of these films was also found in the glass transition of the PVDF component that induces small changes in the paramagnetic component.

Energy Storage Performance of Polymer-Based Dielectric Composites with Two-Dimensional Fillers

Dielectric capacitors have garnered significant attention in recent decades for their wide range of uses in contemporary electronic and electrical power systems. The integration of a high breakdown field polymer matrix with various types of fillers in dielectric polymer nanocomposites has attracted significant attention from both academic and commercial sectors. The energy storage performance is influenced by various essential factors, such as the choice of the polymer matrix, the filler type, the filler morphologies, the interfacial engineering, and the composite structure. However, their application is limited by their large amount of filler content, low energy densities, and low-temperature tolerance. Very recently, the utilization of two-dimensional (2D) materials has become prevalent across several disciplines due to their exceptional thermal, electrical, and mechanical characteristics. Compared with zero-dimensional (0D) and one-dimensional (1D) fillers, two-dimensional fillers are more effective in enhancing the dielectric and energy storage properties of polymer-based composites. The present review provides a comprehensive overview of 2D filler-based composites, encompassing a wide range of materials such as ceramics, metal oxides, carbon compounds, MXenes, clays, boron nitride, and others. In a general sense, the incorporation of 2D fillers into polymer nanocomposite dielectrics can result in a significant enhancement in the energy storage capability, even at low filler concentrations. The current challenges and future perspectives are also discussed.

Kinetic study of polydopamine sphere synthesis using TRIS: relationship between synthesis conditions and final properties

The synthesis and characterization of polydopamine (PDA) using dopamine (DA) as the monomer and (hydroxymethyl)aminomethane (TRIS) as the oxidant is studied. The effect of temperature and TRIS concentration on the kinetics of dopamine polymerization is evaluated, and the kinetic parameters are also calculated. Three TRIS concentrations are used to assess their effect on DA polymerization kinetics. The reaction at 1.5 mmol of TRIS shows a sustained increase of the rate constant with temperature from 2.38 × 10^-4 to 5.10 × 10^-4 when the temperature is increased from 25 to 55 °C; however, not all reactions follow an Arrhenius law. In addition, the correlation between the synthesis parameters and morphological, structural, and thermal properties of polydopamine is established. The morphology of the PDA particles is evaluated by Scanning Electron Microscopy (SEM), the relationships between the diameter, distribution size, and the rate constant. Thermal characterization by Differential Scanning Calorimetry (DSC) shows an endothermic transition around 130 °C associated with the melting of PDA's regular structure. It is supported by structural studies, such as infrared and Raman spectroscopy and X-ray Diffraction (XRD), by observing a broad peak at 23.1° (2θ) that fits with a graphitic-like structure of PDA.

Mussel-Inspired Two-Dimensional Halide Perovskite Facilitated Dopamine Polymerization and Self-Adhesive Photoelectric Coating

Polydopamine (PDA) is a good adhesion agent for lots of gels inspired by the mussel, whereas hybrid organic-inorganic perovskites (HOIPs) usually exhibit extraordinary optoelectronic performance. Herein, mussel-inspired chemistry has been integrated with two-dimensional HOIPs first, leading to the preparation of new crystal (HDA)₂PbBr₄ (1) (DA = dopamine). The organic cation dopamine can be introduced into PDA resulting in a thin film of (HPDA)₂PbBr₄ (PDA-1). The dissolved inorganic components of layered perovskite in DMF solution together with H₂O₂ addition can facilitate DA polymerization greatly. More importantly, PDA-1 can inherit an excellent semiconductor property of HOIPs and robust adhesion of the PDA hydrogel resulting in a self-adhesive photoelectric coating on various interfaces.

Biomimetically Inspired Highly Homogeneous Hydrophilization of Graphene with Poly(l-DOPA): Toward Electroconductive Coatings from Water-Processable Paints

Water-based processing of graphene-typically considered as physicochemically incompatible with water in the macroscale-emerges as the key challenge among the central postulates of green nanotechnology. These problematic concerns are derived from the complex nature of graphene in the family of sp2-carbon nanoallotropes. Indeed, nanomaterials hidden under the common "graphene" signboard are very rich in morphological and physicochemical variants. In this work, inspired by the adhesion chemistry of mussel biomaterials, we have synthesized novel, water-processable graphene-polylevodopa (PDOPA) hybrids. Graphene and PDOPA were covalently amalgamated via the "growth-from" polymerization of l-DOPA (l-3,4-dihydroxyphenylalanine) monomer in air, yielding homogeneously PDOPA-coated (23 wt %) (of thickness 10-20 nm) hydrophilic flakes. The hybrids formed >1 year stable and water-processable aqueous dispersions and further conveniently processable paints of viscosity 0.4 Pa·s at 20 s-1 and a low yield stress τ0 up to 0.12 Pa, hence exhibiting long shelf-life stability and lacking sagging after application. Demonstrating their applicability, we have found them as surfactant-like nanoparticles stabilizing the larger, pristine graphene agglomerates in water in the optimized graphene/graphene-PDOPA weight ratio of 9:1. These characteristics enabled the manufacture of conveniently paintable coatings of low surface resistivity of 1.9 kΩ sq-1 (0.21 Ω·m) which, in turn, emerge as potentially applicable in textronics, radar-absorbing materials, or electromagnetic interference shielding.

Piezoelectric Materials for Energy Harvesting and Sensing Applications: Roadmap for Future Smart Materials

Piezoelectric materials are widely referred to as "smart" materials because they can transduce mechanical pressure acting on them to electrical signals and vice versa. They are extensively utilized in harvesting mechanical energy from vibrations, human motion, mechanical loads, etc., and converting them into electrical energy for low power devices. Piezoelectric transduction offers high scalability, simple device designs, and high-power densities compared to electro-magnetic/static and triboelectric transducers. This review aims to give a holistic overview of recent developments in piezoelectric nanostructured materials, polymers, polymer nanocomposites, and piezoelectric films for implementation in energy harvesting. The progress in fabrication techniques, morphology, piezoelectric properties, energy harvesting performance, and underpinning fundamental mechanisms for each class of materials, including polymer nanocomposites using conducting, non-conducting, and hybrid fillers are discussed. The emergent application horizon of piezoelectric energy harvesters particularly for wireless devices and self-powered sensors is highlighted, and the current challenges and future prospects are critically discussed.

Vinylidene fluoride polymerization by metal-free selective activation of hydrogen peroxide: microstructure determination and mechanistic study

Hydrogen peroxide-initiated radical polymerization of vinylidene fluoride (VDF) at 130 °C in dimethyl carbonate is presented.

Cellulose/BaTiO3 nanofiber dielectric films with enhanced energy density by interface modification with poly(dopamine)

Flexible electrostatic capacitors have many potential applications in modern electric power systems. In this study, flexible cellulose-based dielectric films were prepared by compositing regenerated cellulose (RC) and one-dimensional BaTiO₃ nanofiber (BTNF) via a simple and environmentally friendly process. To improve compatibility and distributional homogeneity of the fillers/matrix, BTNF was surface modified by dopamine to prepare the poly(dopamine) modified BTNF (PDA@BTNF). The obtained RC/PDA@BTNF composite films (RC-PDA@BTNF) possessed higher dielectric constant and breakdown strength than those of the RC and RC/BTNF composite films. In particular, RC/PDA@BTNF composite films with 2 vol% PDA@BTNF (RC-2PDA@BTNF) exhibited a high discharged energy density of 17.1 J/cm³ at 520 MV/m, which exceeded 40 % compared with that of RC-2BTNF at 460 MV/m. Meanwhile, RC-2PDA@BTNF could continuously work for more than 10,000 times with a high efficiency of 91 %. Furthermore, the composite films could maintain good dielectric properties for a long time when stored in vacuum condition (under 0.3 atm). Therefore, these flexible cellulose-based dielectric materials are promising in the field of novel high-performance film dielectric capacitors.

Ferroelectric behavior in paracrystalline poly(vinyl trifluoroacetate)

Dielectric behavior in paracrystalline poly(vinyl trifluoroacetate) was investigated from the viewpoint of ferroelectricity. This polymer has a large CF3 dipole moment (2.3 Debye) and structural defects due to the atactic sequence in its chain conformation. It is possible to rotate the dipoles in paracrystals with defects under high electric field. The dielectric behavior was measured from 20 to 200 °C. A large dielectric constant and dielectric relaxation strength (Δε = 17 at 110 °C) were observed in the α-relaxation region. Corona poling on the samples was carried out at DC field 80 MV/m and 80 °C. Ferroelectric D–E hysteresis loop was observed under high electric field, and the remanent polarization and coercive field at 40 °C were 15 mC/m2 and 155 MV/m, respectively. Pyroelectric response and thermally stimulated current were measured from the current through the electrode irradiated by a pulsed semiconductor laser. A pyroelectric constant of about 6 μC/m2K was observed, which was stable up to near the poling temperature. The ferroelectricity in poly(vinyltrifluoroacetate) stems from the rotation of molecular chains in its paracrystals and orientation of the CF2 dipoles. Poly(vinyltrifluoroacetate) dielectrics can be used for capacitors with high power density, artificial skins, muscles and other flexible electronics.

Carbonization of Polydopamine-Coating Layers on Boron Nitride for Thermal Conductivity Enhancement in Hybrid Polyvinyl Alcohol (PVA) Composites

Inspired by mussel adhesion proteins, boron nitride (BN) particles coated with homogeneous polydopamine (BNPDA) were prepared, and through an annealing process, a carbonized PDA layer on the surface of BN was obtained, which exhibited a nanocrystalline graphite-like structure. The effect of carbonization of PDA coating layer on BN particles was characterized by various analytical techniques including SEM, TEM, Raman spectroscopy, and XPS. When the resulting particles were used as a thermally conductive filler for polyvinyl alcohol (PVA) composite films, enhanced thermal conductivity was observed compared to raw BN composite due to the ordered structure and improved solubility in water. Furthermore, the homogeneous dispersion of the filler and excellent flexibility of the modified composite film with 21 wt % filler may be attributed to compatibility with the PVA chain. As the whole fabrication process did not use toxic chemicals (mainly water was used as the solvent), it may contribute to green and sustainable chemistry.

An alternating multilayer architecture boosts ultrahigh energy density and high discharge efficiency in polymer composites

Poly(vinylidene fluoride) (PVDF)-based polymers with excellent flexibility and relatively high permittivity are desirable compared to the traditional bulk ceramic in dielectric material applications. However, the low discharge efficiency (<70%) caused by the severe intrinsic dielectric loss of these polymers result in a decrease in their breakdown strength and other problems, which limit their widespread applications. To address these outstanding issues, herein, we used a stacking method to combine poly(methyl methacrylate) (PMMA) with poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) for the synthesis of a series of alternating multilayer films with different layers. Benefitting from the blocking effect of the multilayer structure and excellent insulation performance of PMMA, simultaneous improvements in the breakdown strength and discharge efficiency of the multilayer films were achieved. Compared with the pure polymer films and other multilayer films with different layers, the film with a 9-layer structure exhibited the highest energy storage density of 25.3 J cm⁻³ and extremely high discharge efficiency of 84% at 728 MV m⁻¹. Moreover, the charge and discharge performance of the other multilayer films were also better than that of P(VDF-HFP). In addition, it was also found that for the multilayer composite films with the same components, the blocking effect was reinforced with an increase in the number of layers, which led to a significant improvement in the breakdown strength. We consider that the multilayer structure can correlate with the dielectric properties of different polymer materials to enhance the energy storage of composite materials, and will provide a promising route to design high dielectric performance devices.

Poly(vinylidene fluoride) (PVDF)-based polymers with excellent flexibility and high breakdown strengths are desirable compared to the traditional bulk ceramic in dielectric material applications.

Enhanced Dielectric Performance of P(VDF-HFP) Composites with Satellite-Core-Structured Fe2O3@BaTiO3 Nanofillers

Polymer dielectric materials are extensively used in electronic devices. To enhance the dielectric constant, ceramic fillers with high dielectric constant have been widely introduced into polymer matrices. However, to obtain high permittivity, a large added amount (>50 vol%) is usually needed. With the aim of improving dielectric properties with low filler content, satellite–core-structured Fe₂O₃@BaTiO₃ (Fe₂O₃@BT) nanoparticles were fabricated as fillers for a poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix. The interfacial polarization effect is increased by Fe₂O₃ nanoparticles, and thus, composite permittivity is enhanced. Besides, the satellite–core structure prevents Fe₂O₃ particles from directly contacting each other, so that the dielectric loss remains relatively low. Typically, with 20 vol% Fe₂O₃@BT nanoparticle fillers, the permittivity of the composite is 31.7 (1 kHz), nearly 1.8 and 3.0 times that of 20 vol% BT composites and pure polymers, respectively. Nanocomposites also achieve high breakdown strength (>150 KV/mm) and low loss tangent (~0.05). Moreover, the composites exhibited excellent flexibility and maintained good dielectric properties after bending. These results demonstrate that composite films possess broad application prospects in flexible electronics.

Plasma functional polymerization of dopamine using atmospheric pressure plasma and a dopamine solution mist

By using DBD-type atmospheric pressure plasmas and a dopamine solution mist formed by a piezoelectric module, the possibility of depositing functional polymer films showing the physical and chemical characteristics of polydopamine without breaking the functional group of the dopamine has been investigated for different plasma voltages. The higher DBD voltages up to 3.0 kV decreased the functional groups such as catechol and amine (N/C ratio) relative to dopamine in the deposited polymer by increasing the dissociation of dopamine into atoms and small molecules due to higher electron energies. In contrast, the lower DBD voltages up to 1.5 kV increased the functional group and N/C ratio of dopamine in the deposited polymer by keeping the molecular structures of the dopamine due to lower electron energies. Therefore, the polymer deposited at the lower DBD voltages showed lower contact angles and higher metal absorption properties which are some of the surface modification characteristics of polydopamine. When the metal absorption properties of the polydopamine-like film deposited using the atmospheric pressure plasma of a low DBD voltage with a dopamine solution mist were compared with other metal absorbers for Cu, As, and Cr, the polydopamine-like film exhibited superior metal absorption properties. It is believed that this atmospheric pressure plasma process can be also applied to the plasma polymerization of other monomers without breaking the functional groups of the monomers.

Surface Deposition of Juglone/FeIII on Microporous Membranes for Oil/Water Separation and Dye Adsorption

Deposition of dopamine and tannic acid has received great attention in the fields of surface and interface science and technology. The deposition behaviors of various metal-phenolic systems have been investigated, and it is generally accepted that at least one catechol group is essential to the formation of the coatings. Herein, we report a novel and effective surface-coating system based on the coordination complexes of Fe^III ions with a natural product juglone that contains only one phenolic hydroxyl. We investigated the deposition behaviors of this novel system on various substrates. Microporous polypropylene membrane modified with juglone/Fe^III coatings is superhydrophilic and underwater superoleophobic, showing high separation efficiency and good reusability for various oil/water emulsions. In addition, the modified membrane can adsorb anionic dyes and selectively remove them from dye mixtures with high efficiency. We further demonstrated that the coating is a result of the synergetic effect of juglone/Fe^III coordination and Fe^III hydrolysis. This work not only provides new insights into surface deposition systems but also expands the polyphenol family for surface coatings of multifunctional materials.

Modulating interfacial charge distribution and compatibility boosts high energy density and discharge efficiency of polymer nanocomposites

Polymer nanocomposite dielectrics, composed of polymer matrices with high breakdown strength and nanofillers with high dielectric constant, can achieve outstanding energy density. However, the great difference of intrinsic surface properties between the polymer and nanofillers will lead to poor compatibility and thus damage the dielectric properties of the composites. Introducing a transition layer to the filler surface can effectively reduce the degree of mismatch. In this work, we use a “direct in situ polymerization” method to synthesize core–shell BaTiO₃ nanoparticles (BTO_nps) with three types of stable and dense fluoro-polymer shells, e.g., poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA), poly(2,2,3,4,4,4-hexafluorobutyl methacrylate) (PHFBMA), and poly(1H,1H,7H-dodecafluoroheptyl methacrylate) (PDFHMA), and individually disperse them into the poly(vinylidene fluoride-co-hexafluoro propylene) (P(VDF-HFP)) matrix. Benefitting from the good interaction between the fluorine-containing segments in the shell polymer and the matrix segments, the dispersion of core–shell BTO_nps and their compatibility with P(VDF-HFP) are improved, which leads to a significant improvement in the dielectric properties of the nanocomposites. The results show that BTO@PDFHMA/P(VDF-HFP) composite exhibits an ultrahigh energy density of 16.8 J cm⁻³ at 609 MV m⁻¹ with particle loading amount of 15 wt%, compared to 11.5 J cm⁻³ at 492 MV m⁻¹ for a conventional solution blended BTO/P(VDF-HFP) composite. Meanwhile, the discharge efficiency is enhanced from ∼62 to ∼78%. It is elucidated that the core–shell strategy can achieve improved particle dispersion and dielectric properties. We consider that this simple method can well achieve the preparation of core–shell structures in dielectric nanocomposites.

Fluoro-polymer shells concomitantly enhance the energy density and discharge efficiency by active interactions with BTO cores and P(VDF-HFP).

Surface Modification of Magnetic Iron Oxide Nanoparticles

Functionalized iron oxide nanoparticles (IONPs) are of great interest due to wide range applications, especially in nanomedicine. However, they face challenges preventing their further applications such as rapid agglomeration, oxidation, etc. Appropriate surface modification of IONPs can conquer these barriers with improved physicochemical properties. This review summarizes recent advances in the surface modification of IONPs with small organic molecules, polymers and inorganic materials. The preparation methods, mechanisms and applications of surface-modified IONPs with different materials are discussed. Finally, the technical barriers of IONPs and their limitations in practical applications are pointed out, and the development trends and prospects are discussed.

Dielectric Electroactive Polymers with Chemical Pre-Strain: An Experimentally Validated Model

Dielectric electroactive polymer materials represent a distinct group of smart materials that are capable of converting between electrical and mechanical energy. This research focuses on the modeling and testing of an industrial grade fluoropolymer material for its feasibility as a dielectric elastomer electroactive polymer. Through this process, a novel chemical pre-strain method was tested, along with a one-step process for application of pre-strain and addition of an elastomer conductive layer. Modeled and experimental actuators produced approximately 1 mm displacements with 0.625 W of electrical power. The displacement of the actuators was characterized, and the effects of multiple parameters were modeled and analyzed.

Advanced capability of radially aligned fibrous scaffolds coated with polydopamine for guiding directional migration of human mesenchymal stem cells

In a large tissue defect, faster migration of adjacent tissue toward the defect shortens the tissue regeneration time. Little has been explored on guiding of directional migration from all fronts of the defect boundary towards the center in tissue engineering. This paper demonstrates the effect of radially aligned fibrous scaffolds (RAFSs) coated with polydopamine in order to guide directional migration of human mesenchymal stem cells (hMSCs). RAFSs were electrospun using a collector with a set of electrodes, each constructed with a metallic ring and a point. The polydopamine was then coated by dipping the scaffolds in a dopamine solution (PD-RAFS). The RAFSs exhibited radial distribution of the fibers from the peripheral region toward the center, and polydopamine was uniformly coated over the entire surface by presenting characteristics of the aromatic ring from dopamine. When hMSCs were seeded on the scaffolds, cells grew in an elongated form toward the center along the fiber direction. In particular, the polydopamine coating improved adhesion and spreading of hMSCs on the scaffolds while preserving initial cell orientation. The hMSCs migrated toward the center of the scaffolds at the border of the seeded area; it was enhanced in the order of PD-RAFS > RAFS > random fibrous scaffolds. Therefore, PD-RAFSs can be utilized as an alternate scaffold that can lead to fast and directional migration of cells for finally facilitating tissue regeneration.

2D Ti3C2Tx (MXene)-reinforced polyvinyl alcohol (PVA) nanofibers with enhanced mechanical and electrical properties

Novel 2D Ti3C2Tx (MXene)-reinforced polyvinyl alcohol (PVA) nanofibers have been successfully fabricated by an electrospinning technique. The high aspect ratio, hydrophilic surfaces, and metallic conductivity of delaminated MXene nanosheet render it promising nanofiller for high performance nanocomposites. Cellulose nanocrystals (CNC) were used to improve the mechanical properties of the nanofibers. The obtained electrospun nanofibers had diameter from 174 to 194 nm depending on ratio between PVA, CNC and MXene. Dynamic mechanical analysis demonstrated an increase in the elastic modulus from 392 MPa for neat PVA fibers to 855 MPa for fibers containing CNC and MXene at 25°C. Moreover, PVA nanofibers containing 0.14 wt. % Ti3C2Tx exhibited dc conductivity of 0.8 mS/cm conductivity which is superior compared to similar composites prepared using methods other than electrospinning. Improved mechanical and electrical characteristics of the Ti3C2Tx /CNC/PVA composites make them viable materials for high performance energy applications.

Improved dielectric constant and breakdown strength of γ-phase dominant super toughened polyvinylidene fluoride/TiO2 nanocomposite film: an excellent material for energy storage applications and piezoelectric throughput

Titanium dioxide (TiO₂) nanoparticles (NPs) embedded γ-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m^-1). It also exhibits a high energy density of 4 J cm^-3 which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO₂ NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects

Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers or polymer matrix help in further improving the dielectric properties as compared to two-phase nanocomposites. Recent research has been focused on altering the dielectric properties of different materials while also maintaining their superior flexibility. Flexible polymer nanocomposites are the best candidates for application in various fields. However, certain challenges still present, which can be solved only by extensive research in this field.

Preparation and dielectric properties of polymer composites incorporated with polydopamine@AgNPs core–satellite particles

Polydopamine@AgNPs (PDA@AgNPs) core–satellite particles were fabricated by self-polymerization of dopamine and in situ reduction of Ag⁺ on the as-formed PDA surface.

Effect of the Modifier Structure on the Performance of Barium Titanate/Poly(vinylidene fluoride) Nanocomposites for Energy Storage Applications

Surface modification on ceramic fillers is of interest to help improve their compatibility in ceramic/polymer nanocomposites and, if possible, to control the influence of modifiers on the performance of the nanocomposites. In this paper, four kinds of small-molecule modifiers were chosen to treat the surface of BT nanoparticles, and the PVDF-based nanocomposites filled with the modified BT nanoparticles were prepared. The influences of modifiers on compatibility, permittivity, breakdown strength and polarization have been systematically investigated in order to identify the optimal surface modifier to enhance the energy density of the nanocomposites. Due to different structures (including type, number, and position of functional groups in molecules), the modifiers show different effects on the permittivity of the nanocomposites, while the breakdown strengths are all significantly improved. Consequently, the discharged energy densities of nanocomposites modified by 2,3,4,5-tetrafluorobenzoic acid and phthalic acid increase 35.7% and 37.7%, respectively, compared to BT/PVDF, indicating their potential as high energy density capacitors.