Conductive Pathways Research Articles

Photosensitive polyimide enabled simple, reversible and environmentally friendly selective metallization on diverse substrates

For breaking through the limitation of metal patterning in constructing conductive pathways of electronic devices, which is proposed to be an upgrade of traditional etching technique, a photo-reversible, transparent and soluble polyimide carrying spiropyran side chains is synthesized. The merocyanine isomers produced from the spiropyran moieties under digitalized ultraviolet irradiation bind the silver−histidine complexes in water, while the absorbed silver ions are in-situ reduced into metal silver seeds by the photo-generated radicals from histidine molecules, catalyzing copper deposition and yielding the desired copper patterns. Accordingly, the conventional time-consuming steps (like surface modification, immobilization of catalytic ions and (photo)chemical reduction) are simplified to a single one, and the environmentally unfriendly solvent and costly/toxic palladium reagent are excluded. The Cu patterns deposited on the polyimide show high resolution, electrical conductivity (1.785 × 10−6 Ω‧cm), adhesion strength (18.14 MPa) and fatigue resistance (> 2.6 million cycles of bending). Due to the absence of invasive surface treatments (e.g., surface hydrolysis and laser direct structuring), extremely low surface roughness of 7.83 nm is achieved. Besides, the developed strategy can be easily expanded to stretchable elastomer and other organic/inorganic substrates with irregular surfaces, showing promising application prospects. The solubility of the polyimide and ultraviolet/visible light triggered reversibility of the included spiropyran groups further enable repeated recycling, erasing and re-patterning.

Growth of polyaniline nanowire arrays on boron nitride microrods enables high‐efficient thermal transport

AbstractThe rapid development of flexible conductive materials has promoted the research on conductive polymer (CP)‐based materials. However, CPs have relatively low thermal conductivity (TC), which can result in severe heat dissipation problems for device applications. In this work, core–sheath structured polyaniline@boron nitride (BN@PANI) composites were prepared by in‐situ growth strategy, in which PANI nanowire arrays were uniformly anchored to the surface of BN microrods. Thanks to the particular structure, the as‐prepared BN@PANI composite shows excellent thermal management capabilities. Specifically, the TC of the BN@PANI composite is 4.32 W/m·K at low BN loading of 10 wt%, which is almost 17.8 times that of pure PANI. Moreover, the excellent heat dissipation performance is intuitively presented through infrared imaging technology. Impressively, the PANI nanowire arrays are vertically arranged on the BN surface to form a conductive pathway, which results in conductivity comparable to pure PANI. This work broadens the ideas for preparing high‐performance CP‐based composites by using insulating fillers.Highlights Core–sheath structured BN@PANI composites were prepared by an in‐situ growth strategy. The thermal conductivity of composite was 4.32 W/m·K at 10 wt% BN loading. The introduction of BN had little effect on the conductivity of PANI. The BN@PANI composites possessed excellent thermal management capability. This work contributes to understanding heat transport in conductive polymers.

Stretch-Induced Conductivity Enhancement in Highly Conductive and Tough Hydrogels.

The resistance of gels and elastomers increases significantly with tensile strain, which reduces conductive stability and restricts their use in stable and reliable electronics. Here, highly conductive tough hydrogels composed of silver nanowires (AgNWs), liquid metal (LM), and poly(vinyl alcohol) (PVA) are fabricated. The stretch-induced orientations of AgNWs, deformable LM, and PVA nanocrystalline create conductive pathways, enhancing the mechanical properties of the hydrogels, including increased ultimate fracture stress (13-33MPa), strain (3000-5300%), and toughness (390.9-765.1MJ m-3). Notably, the electrical conductivity of the hydrogels is significantly improved from 4.05 × 10-3 to 24 S m-1 when stretched to 4200% strain, representing a 6000-fold enhancement. The incorporation of PVA nanocrystalline, deformable LM, and AgNWs effectively mitigates stress concentration at the crack tip, thereby conferring crack propagation insensitivity and fatigue resistance to the hydrogels. Moreover, the hydrogels are designed with a reversible crosslinking network, allowing for water-induced recycling.

Bioinspired Thermal Conductive Cellulose Nanofibers/Boron Nitride Coating Enabled by Co-Exfoliation and Interfacial Engineering.

Thermal conductive coating materials with combination of mechanical robustness, good adhesion and electrical insulation are in high demand in the electronics industry. However, very few progresses have been achieved in constructing a highly thermal conductive composites coating that can conformably coat on desired subjects for efficient thermal dissipation, due to their lack of materials design and structure control. Herein, we report a bioinspired thermal conductive coating material from cellulose nanofibers (CNFs), boron nitride (BN), and polydopamine (PDA) by mimicking the layered structure of nacre. Owing to the strong interfacial strength, mechanical robustness, and high thermal conductivity of CNFs, they do not only enhance the exfoliation and dispersion of BN nanoplates, but also bridge BN nanoplates to achieve superior thermal and mechanical performance. The resulting composites coating exhibits a high thermal conductivity of 13.8 W/(m·K) that surpasses most of the reported thermal conductive composites coating owing to the formation of an efficient thermal conductive pathway in the layered structure. Additionally, the coating material has good interface adhesion to conformably wrap around various substrates by scalable spray coating, combined with good mechanical robustness, sustainability, electrical insulation, low-cost, and easy processability, which makes our materials attractive for electronic packaging applications.

Research Progress in Nano Materials and Structural Designs for Flexible Piezoresistive Sensors

This review provides an overview of recent advances in the materials and structural design of flexible piezoresistive sensors, which are of significant interest as smart devices in the Fourth Industrial Revolution. Recent research has focused on addressing demand for a wide pressure range and high sensitivity for use in diverse applications. In terms of sensor materials, this review begins by introducing elastomers used for matrix and substrate, which provide exceptional conformability to curved surfaces and mechanical flexibility to withstand stretching and bending. They can also incorporate sensing materials in various forms of nanostructures capable of effectively transmitting electrical signals, exploiting the nanomaterial’s electrical properties and conductivity pathways formation mechanisms under pressure, which define the sensor’s characteristics. Additionally, this review explores structural design considerations, including different types of microstructures that can deform easily even under low pressure, enhancing sensor sensitivity, as well as hierarchical structures capable of gradual changes in contact area to provide a wide range of operating pressures. Moreover, the review discusses time- and cost-efficient microfabrication techniques to facilitate practical utilization of the device. This review then summarizes the applications of high-performance sensors in fields such as health monitoring, including pulse detection and motion tracking, robotics, and human-machine interaction involving components such as touch screens and keypads.

Facilitating electroless metalization of blind holes in glass substrates by electrochemical discharge-assisted surface roughening

This study introduces a novel approach involving the utilization of electrochemical discharges (ECD) to roughen a glass substrate to enhance the electroless metalization within blind holes. An array of 6 × 6 microholes was machined in a glass substrate using room-temperature-based Ultrasonic machining (USM) followed by electroless nickel and copper electrodeposition. Oxidation of the electroless seed layer obstructing the conductive pathway during electrodeposition and constraints to the flow of electroless solution into microholes resulted in unfilled vias. Roughening of the glass surface with ECD enabled the deposition of a thicker electroless seed layer and also infiltrated electroless solution into microholes through a network of valleys and channels generated on the top surface. A continuous electroless seed layer deposition was demonstrated in a blind via with an aspect ratio (AR) of nearly 1.5.

Stretchable and Highly Sensitive Flexible Strain Sensor Based on a Three‐Layer Core–Shell Structure of Polydopamine/Polypyrrole@Natural Rubber for Human Activity Monitoring

In recent years, flexible strain sensors with a wide detection range and high sensitivity have garnered significant attention for human health monitoring. However, fabricating strain sensors with a broad strain range while retaining high sensitivity remains a major challenge. Herein, a green and facile method is successfully developed to fabricate the polydopamine/polypyrrole@natural rubber (PDA/PPy@NR)‐based strain sensor with a three‐layer core–shell structure. PDA and PPy are coated uniformly onto the surface of the NR nanosphere by in situ polymerization. The electromechanical and strain sensing properties of the fabricated composite are investigated. The homogeneous coating of PPy and PDA layers has facilitated the formation of continuous conductive pathways within the NR matrix, even at low loading levels. Consequently, the strain sensor exhibits remarkable sensitivity over a wide strain range (≈800%) and long‐term reliability (2500 cycles at 50%). The PDA/PPy@NR strain sensor shows an exceptionally high gauge factor value (142.6) and a short response time (125 ms). Furthermore, this PDA/PPy@NR strain sensor can effectively detect and capture subtle and large human movements such as limb joints and facial movements as well as even distinguish the pronunciation of different words. The PDA/PPy@NR strain sensor holds great promise for integration into flexible wearable electronics.

Learning in colloidal polyaniline nanorods

Liquid-based computing media are massively parallel computing devices with high fault-tolerance and self-healing capabilities. They can compute by propagating and interacting phase waves or by changing their internal coordination.Colloidal suspensions of conductive polymer nanorods are expected to be interesting candidates for developing the computing subsystem in such applications, because of their anisometry which makes them particularly susceptible to electrical fields.In this work, we investigateda suspension of polyaniline nanorods (NRs) to explorethe potential of generatinglearning mechanisms in the colloid and applyingthem in the computing system of future cybernetic systems. We demonstrated that learning, as expressed in the formation of programmable conductive pathways leading to distinct states, can be implemented using Alternated Current (AC) electrical stimulation. We achievedrepeatable programming of colloid resistance anisotropy that can be easily mapped into binary logic, demonstrating that this is due to the AC field effects on the hydrogen bonds that stabilise the dispersoids in the solvent as well as the charges' orientation inside the polymeric chains. We also influencedthe conductivity of polyaniline (PANI) NRs by changing their molecular conformation. The findings establish robustprotocols for programming future liquid robots.

Optical, conductive, and ferroelectric properties of the first layer of dip-coated BiFeO3 films from methoxyethanol and acetic acid-based chemical dissolvents

The overall performance of the multilayer resulting in a sol-gel bismuth ferrite (BiFeO3) film will be primarily determined by the properties of the first layer, but this has yet to receive much attention, even though chemical and morphological defects of this layer can accumulate as the number of layers increases. Here, we perform an optical, conductive, and ferroelectric study of first layer (L 1) dip-coating sol-gel BiFeO3 films using two routes that vary only in the dissolvent; the first one is based on 2-methoxyethanol (MOE), and the second one on acetic acid (AA) with some MOE (AA-MOE). Tauc plots reveal a band gap of 2.43 eV and 2.75 eV for MOE (30 ± 5 nm thick) and AA-MOE (35 ± 5 nm thick) films, respectively. MOE films showed a dielectric function with features at ∼2.5 eV, ∼3.1 eV, and ∼3.9 eV, which were associated with charge-transfer transitions, but such features are absent in AA-MOE films. Advanced atomic force microscopy techniques were used to identify the fine features or defects of the BiFeO3 films: The conductive maps show that the charge transport pathways in both film routes are controlled by nanometer defects rather than grain or grain boundary defects. Current-voltage curves reveal high conductive pathway at a lower voltage for the MOE films than for AA-MOE films. The piezoelectric coefficient for MOE films was ∼20% higher than AA-MOE films. Both deposition methods yield ferroelectric films with an electromechanical strain controlled by the piezoelectric effect and minimal contribution from electrostriction. An optimization for the AA-MOE-based route in the withdrawal speed results in a significant reduction of morphological defects and a more than twofold increase in the piezoelectric coefficient. Our results broaden the understanding of optical and ferroelectric BiFeO3 films based on a chemical solution by dip-coating.

Atomic Defect Quantification by Lateral Force Microscopy.

Atomic defects in two-dimensional (2D) materials impact electronic and optoelectronic properties, such as doping and single photon emission. An understanding of defect-property relationships is essential for optimizing material performance. However, progress in understanding these critical relationships is hindered by a lack of straightforward approaches for accurate, precise, and reliable defect quantification on the nanoscale, especially for insulating materials. Here, we demonstrate that lateral force microscopy (LFM), a mechanical technique, can observe atomic defects in semiconducting and insulating 2D materials under ambient conditions. We first improve the sensitivity of LFM through consideration of cantilever mechanics. With the improved sensitivity, we use LFM to locate atomic-scale point defects on the surface of bulk MoSe2. By directly comparing LFM and conductive atomic force microscopy (CAFM) measurements on bulk MoSe2, we demonstrate that point defects observed with LFM are atomic defects in the crystal. As a mechanical technique, LFM does not require a conductive pathway, which allows defect characterization on insulating materials, such as hexagonal boron nitride (hBN). We demonstrate the ability to observe intrinsic defects in hBN and defects introduced by annealing. Our demonstration of LFM as a mechanical defect characterization technique applicable to both conductive and insulating 2D materials will enable routine defect-property determination and accelerate materials research.

Polyurethane composite films with self-assembled graphene fluoride: Constructing conductive pathways for thermal management with electrical insulation

Polymer composites incorporating carbon-based fillers have been demonstrated to have high thermal conductivity (TC), yet their high electrical conductivity restricts their utility in electronic devices. As a solution to this issue, we report graphene fluoride (GF) incorporated thermoplastic polyurethane (TPU) composites that are both thermally conductive and electrically insulating. The TPU composites, engineered for both high TC and electrical insulation while maintaining flexibility, were fabricated using a combination of electrospinning, dip-coating, and hot-pressing techniques. This study aimed to investigate the effects of various dip-coating cycles on the in-plane thermal conductivity (λ∥) of GF@TPU composites. Noticeably, GF@TPU composites exhibited an outstanding TC, reaching up to 13.5 W m−1 K−1 with 10 vol% GF loading, marking a 75-fold increase compared to the neat TPU films. Moreover, the GF@TPU composites exhibited an electrically insulating property of 6.5 × 1010 Ω/m. This work provides a promising strategy to make thermally conductive composites with electrical insulation for thermal management in smart electronics.

Fabrication and investigation of graphene‐loaded triiron tetraoxide/silicone‐rubber electromagnetic shielding composites based on static magnetic‐field–induced orientation

AbstractGraphene‐loaded triiron tetraoxide/silicone‐rubber composites containing highly loaded graphene‐loaded Fe3O4 (Fe3O4@RGO) particles were fabricated using static magnetic field‐induced alignment. The Fe3O4@RGO particles were characterized through Fourier transform infrared, x‐ray diffraction, SEM, and XPS analyses. Subsequently, the influence of added material and the strength of the magnetic field on the alignment distribution of the filler were examined through a synergistic combination of SEM and Raman spectroscopy. The electrical conductivity and electromagnetic shielding properties of the composites were assessed. The electrical conductivity of the composites increased with increasing filler addition, the 25 wt% filler mixture had the fastest curing rate and the maximum torque, and the continued increase in filler addition led to the occurrence of many defects. Concurrently, the alignment distribution of the filler progressively enhances with the augmentation of magnetic field strength. The composites synthesized at 180 mT exhibit the most substantial alignment, facilitating the establishment of effective conductive pathways. This results in a notable enhancement in electromagnetic shielding effectiveness, approximately 400% greater than that of pure silicone rubber and around 40% higher than that of non‐aligned composites. This approach introduces a novel concept for shaping the structural design of flexible electromagnetic shielding materials.Highlights Highly loaded Fe3O4@RGO was prepared by self‐assembly. The continuous phase structure of Fe3O4@RGO oriented was assessed. Fully oriented Fe3O4@RGO promotes the formation of conductive pathways. Fully oriented Fe3O4@RGO reduced the SER by 13% and increased the SEA by 67%.

Construction of micro-nano hybrid structure based on carbon nanotube whisker and alumina for thermally conductive yet electrically insulating silicone rubber composites

High-performance electronics urgently need more effective thermally conductive rubber composites to solve interfacial heat transfer problems in the thermal management systems. Tiny amounts nanocarbon materials (NCM) can significantly improve the thermal conductivity of conventional ceramic-filled rubber composites, but the volume exclusion effect of micrometer ceramic fillers makes NCM highly susceptible to the formation of the conductive pathways, which inevitably leads to the substantial decrease in the volume resistivity of the materials, posing a safety hazard, such as short circuits, to electronic devices. Here, we report an electrostatic self-assembly method to prepare CNW@n-Al2O3 hybrids by loading nano-alumina (n-Al2O3) onto carbon nanotube whiskers (CNW) and co-filling them with micrometer alumina (m-Al2O3) to silicone rubber, constructing a micro-nano-multi-level hybrid network structure, which can fully utilize the high thermal conductivity while shielding the electrical conductivity of CNW. The resulting composite filled with 2 phr of CNW@n-Al2O3 exhibits a significantly enhanced thermal conductivity of 1.137 W/(m·K) and a high volume resistance of 1.323 × 109 Ω cm, and is proved to be used as an excellent thermal interface material to assist the heat dissipation of the microelectronic chip. This study provides a facile and effective strategy for the design of thermally conductive yet electrically insulating rubber composites filled with CNW, which shows a bright application prospect in the thermal management of high-performance electronic devices.

Constructing amino-functionalized flower-shaped ZnO@Al2O3 nanofibers composite membrane (ZANFs/SPSF) with hierarchical proton conductive pathways and excellent methanol resistance

Traditional nanofiber-hybrid proton exchange membranes (PEMs) are limited in their further application due to differences in proton conductivity between vertical and horizontal orientations. In this study, we design and synthesize a novel type aminated flower-shaped ZnO@Al2O3 nanofibers and then filling its three-dimensional interstices with sulfonated polysulfone (SPSF) to obtain a nanofiber composite proton exchange membrane (ZANFs/SPSF). The Al2O3 nanofibers provide long-range and stable proton transport nanochannels in plane, while the flower-shaped ZnO on its surface provide additional vertical transport channels for protons. This combination of 1D and 2D conductive pathways forms a typical 3D hierarchical proton conductive configuration, optimizing the proton transfer pathway. Specifically, the amino groups (-N-H) on the nanofibers surface not only form acid-base pairs with sulfonic acid groups (-SO3H), providing a rich hydrogen bonding network for proton hopping, but also have a similar structure to the polyether sulfone groups (–SO2–NH-), which significantly improves the compatibility between the nanofibers and SPSF. Additionally, the flower-like pleated surface of the nanofibers has a high contact area with the SPSF, providing more proton hopping sites, improving the utilization efficiency of proton carriers, and also resulting in a more stable structure. Moreover, the crosslinked network of nanofibers serves as a barrier to further inhibit methanol permeation. The ZANFs/SPSF exhibits excellent parallel proton conductivity of 348 mS cm−1 at 80 °C and 100% RH, which is 2.7 times higher than that of SPSF under the same conditions, and achieves a peak power density of 405.7 mW cm−2. This approach presents a unique perspective for the preparation of high-performance PEMs for methanol fuel cells.

Analytical modeling of the electrical conductivity of CNT-filled polymer nanocomposites

Electrical conductivity of most polymeric insulators can be drastically enhanced by introducing a small volume fraction [Formula: see text] of conductive nanofillers. These nanocomposites find wide-ranging engineering applications from cellular metamaterials to strain sensors. In this work, we present a mathematical model to predict the effective electrical conductivity of carbon nanotubes (CNTs)/polymer nanocomposites accounting for the conductivity, dimensions, volume fraction, and alignment of the CNTs. Eshelby’s classical equivalent inclusion method (EIM) is generalized to account for electron-hopping—a key mechanism of electron transport across CNTs, and is validated with experimental data. Two measurements, namely, the limit angle of filler orientation and the probability distribution function, are used to control the alignment of CNTs within the composites. Our simulations show that decreasing the angle from a uniformly random distribution to a fully aligned state significantly reduces the transverse electrical conductivity, while the longitudinal conductivity shows less sensitivity to angle variation. Moreover, it is observed that distributing CNTs with non-uniform probability distribution functions results in an increase in longitudinal conductivity and a decrease in transverse conductivity, with these differences becoming more pronounced as the volume fraction of CNTs is increased. A reduction in CNT length decreases the effective electrical conductivity due to the reduced number of available conductive pathways while reducing CNT diameter increases the conductivity.

Dynamic Adaptive Wrinkle‐Structured Silk Fibroin/MXene Composite Fibers for Switchable Electromagnetic Interference Shielding

AbstractFlexible and dynamic adaptive conductive composite fibers are demanded for functional fabrics and wearable devices, yet the weak interfaces often impair the critical performances for complicated application scenarios. Here, a general and scalable strategy is proposed to construct robust and reversible wrinkle structures on regenerated silk fibroin (RSF) fiber with 2D nanomaterials (i.e., MXene, graphene) by wet‐spinning technique. The dynamic conformation transition of silk fibroin and the core‐shell modulus mismatching together are responsible for the formation of wrinkled structures. Then, it effectively optimizes the interfaces between the assembled nanomaterials and fiber substrate, which significantly reinforce the fibers, complete conductive pathways, and endow exceptional robustness and durability. The MXene‐based fiber shows a high conductivity of ≈1125 S cm−1, far superior tensile strength of 214.3 ± 6.8 MPa and toughness of 15.2 ± 1.5 MJ m−3 as compared to RSF fiber. More interestingly, the transformable wrinkled structure further modulates surface behaviors and properties of the fibers, such as the switchable shielding performances from “off‐state” to “on‐state” induced by humidity. Additionally, the integration of mechanical flexibility and outstanding capacitance (≈829 F cm−3) further expects the great promise of MXene‐based fibers for self‐powered wearable electronics, and intelligent fabrics.

One-step formation of three-dimensional interconnected T-shaped microstructures inside composites by orthogonal bidirectional self-assembly method

ABSTRACT The fillers inside a polymer matrix should typically be self-assembled in both the horizontal and vertical directions to obtain 3-dimentional (3D) percolation pathways, whereby the fields of application can be expanded and the properties of organic-inorganic composite films improved. Conventional dielectrophoresis techniques can typically only drive fillers to self-assemble in only one direction. We have devised a one-step dielectrophoresis-driven approach that effectively induces fillers self-assembly along two orthogonal axes, which results in the formation of 3D interconnected T-shaped iron microstructures (3D-T CIP) inside a polymer matrix. This approach to carbonyl iron powder (CIP) embedded in a polymer matrix results in a linear structure along the thickness direction and a network structure on the top surface of the film. The fillers in the polymer were controlled to achieve orthogonal bidirectional self-assembly using an external alternating current (AC) electric field and a non-contact technique that did not lead to electrical breakdown. The process of 3D-T CIP formation was observed in real time using in situ observation methods with optical microscopy, and the quantity and quality of self-assembly were characterized using statistical and fractal analysis. The process of fillers self-assembly along the direction perpendicular to the electric field was explained by finite element analogue simulations, and the results indicated that the insulating polyethylene terephthalate (PET) film between the electrode and the CIP/prepolymer suspension was the key to the formation of the 3D-T CIP. In contrast to the traditional two-step method of fabricating sandwich-structured film, the fabricated 3D-T CIP film with 3D electrically conductive pathways can be applied as magnetic field sensor.

Structural Insight into Protective Alumina Coatings for Layered Li-Ion Cathode Materials by Solid-State NMR Spectroscopy.

Layered transition metal oxide cathode materials can exhibit high energy densities in Li-ion batteries, in particular, those with high Ni contents such as LiNiO2. However, the stability of these Ni-rich materials often decreases with increased nickel content, leading to capacity fade and a decrease in the resulting electrochemical performance. Thin alumina coatings have the potential to improve the longevity of LiNiO2 cathodes by providing a protective interface to stabilize the cathode surface. The structures of alumina coatings and the chemistry of the coating-cathode interface are not fully understood and remain the subject of investigation. Greater structural understanding could help to minimize excess coating, maximize conductive pathways, and maintain high capacity and rate capability while improving capacity retention. Here, solid-state nuclear magnetic resonance (NMR) spectroscopy, paired with powder X-ray diffraction and electron microscopy, is used to provide insight into the structures of the Al2O3 coatings on LiNiO2. To do this, we performed a systematic study as a function of coating thickness and used LiCoO2, a diamagnetic model, and the material of interest, LiNiO2. 27Al magic-angle spinning (MAS) NMR spectra acquired for thick 10 wt % coatings on LiCoO2 and LiNiO2 suggest that in both cases, the coatings consist of disordered four- and six-coordinate Al-O environments. However, 27Al MAS NMR spectra acquired for thinner 0.2 wt % coatings on LiCoO2 identify additional phases believed to be LiCo1-xAlxO2 and LiAlO2 at the coating-cathode interface. 6,7Li MAS NMR and T1 measurements suggest that similar mixing takes place near the interface for Al2O3 on LiNiO2. Furthermore, reproducibility studies have been undertaken to investigate the effect of the coating method on the local structure, as well as the role of the substrate.

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.

Soft-Hard Janus Nanoparticles Triggered Hierarchical Conductors with Large Stretchability, High Sensitivity, and Superior Mechanical Properties.

There is a long-standing conflict between the large stretchability and high sensitivity for strain sensors, a strategy of decoupling the mechanical/electrical module by constructing the hierarchical conductor has been developed in this study. The hierarchical conductor, consisting of a mechanically stretchable layer, a conductive network layer, and a strongly bonded interface, can be produced in a simple one-step process with the aid of soft-hard Janus nanoparticles (JNPs). The introduction of JNPs in the stretchable layer can evenly distribute stress and dissipate energy due to forming the rigid-flexible homogeneous networks. Specifically, JNPs can drive graphene nanosheets (GNS) to fold or curl, creating the unique JNPs-GNS building block that can further construct the conductive network. Due to its excellent deformability to hinder crack propagation, the flexible conductive network could be stretched continuously and the local conductive pathways could be reconstructed. Consequently, the hierarchical conductor could detect both subtle strain of 0-2% and large strain of up to 370%, with a gauge factor (GF) from 66.37 to 971.70, demonstrating outstanding stretchability and sensitivity. And it also owns large tensile strength (5.28MPa) and high deformation stability. This hierarchical design will give graphene-based sensors a major boost in emerging applications.