Formation Of Conductive Network Research Articles

Understanding the dielectric properties and electromagnetic shielding efficiency of zirconia filled epoxy-MWCNT composites

In the present study, hybrid composites are prepared by reinforcing various concentrations of high permittivity zirconia nanofiller into epoxy/CNT compositions to test their usability in EMI shielding applications in the X and Ku bands. ZrO2 nanofiller is added in different proportions to improve absorbance shielding while maintaining the composite conductivity uniform by adding constant CNT concentration to restrict the reflectance shielding. The microscopic studies have revealed an efficient dispersion of ZrO2 nanoparticles in the CNT networks and provided a smoother surface. The presence of zirconia nanofillers increased the dielectric properties, viz. the dielectric constant (194 at 0.1 Hz) and loss tangent (1.57 at 0.1 Hz), respectively, whereas the conductivity was found to be invariantly constant. The increased permittivity of composites enhanced the shielding by absorption, while the shielding by reflection is least influenced by the addition of zirconia nanofiller. The addition of zirconia nanofillers increased the permittivity and tan delta, allowing charges to accumulate at the interfacial areas for incoming EM radiations, resulting in increased absorbance shielding. Limiting the CNT concentration in all composites to the same level resulted in the formation of conductive networks, thus resulting in uniform reflectance shielding for all the hybrid composites in the present study. The dynamic mechanical analysis showed the improvement in the storage modulus and activation energy due to the enhanced interfacial adhesion and cross-linked polymer density.

Preparation and thermoelectric properties of Mn<sub>3</sub>As<sub>2</sub>-doped Cd<sub>3</sub>As<sub>2</sub> nanostructures

Cd<sub>3</sub>As<sub>2</sub>, especially its various nanostructures, has been considered as an excellent candidate for application in novel optoelectronic devices due to its ultrahigh mobility and good air-stability. Recent researches exhibited Cd<sub>3</sub>As<sub>2</sub> as a candidate of thermoelectric materials by virtue of its ultralow thermal conductivity in comparison with other semimetals or metals. In this work, at first <b>(</b> Cd<sub>1–<i>x</i></sub>Mn<sub><i>x</i></sub>)<sub>3</sub>As<sub>2</sub> (<i>x</i> = 0, 0.05, 0.1) bulk alloys are prepared by high-pressure sintering to suppress the volatilization of As element, and then several kinds of Mn<sub>3</sub>As<sub>2</sub>-doped Cd<sub>3</sub>As<sub>2</sub> nanostructures are obtained on mica substrates by chemical vapor deposition (CVD), with bamboo-shoot-nanowire structure forming in a high-temperature region and films in a low-temperature region. Effects of Mn<sub>3</sub>As<sub>2</sub> doping on the crystalline structure, phase compositions, microstructures and thermoelectric properties of the Cd<sub>3</sub>As<sub>2</sub> nanostructures are systematically studied. Energy-dispersive spectrometer (EDS) analysis at various typical positions of the Mn<sub>3</sub>As<sub>2</sub>-doped Cd<sub>3</sub>As<sub>2</sub> nanostructures shows that the Mn content in these nanostructures is in a range of 0.02%–0.18% (atomic percent), which is much lower than the Mn content in <b>(</b> Cd<sub>1–<i>x</i></sub>Mn<sub><i>x</i></sub>)<sub>3</sub>As<sub>2</sub> (<i>x</i> = 0, 0.05, 0.1) parent alloys. The main phases of these nanostructures are all body centered tetragonal <i>α</i> phase with a small amount of primitive tetragonal <i>α</i>′ phase. Doping results in the <i>α</i>″ phase and Mn<sub>2</sub>As impurity phase occurring. The Cd<sub>3</sub>As<sub>2</sub> film presents a self-assembled cauliflower microstructure. Upon Mn<sub>3</sub>As<sub>2</sub> doping, this morphology finally transforms into a vertical-growth seashell structure. In a high temperature region of the mica substrate, a unique bamboo-shoot-nanowire structure is formed, with vertical-growth bamboo shoots connected by nanowires, and at the end of these nanowires grows a white pentagonal flower structure with the highest Mn content of 0.18% (atomic percent) for all the nanostructures. Conductivity of the Cd<sub>3</sub>As<sub>2</sub> film and the bamboo-shoot-nanowire structure are ～20 and 320 S/cm, respectively. The remarkable conductivity enhancement can be attributed to higher crystallinity and the formation of nanowire conductive network, which significantly increase carrier concentration and Hall mobility. The Hall mobility values of the nanowire structures range from 2271 to 3048 cm<sup>2</sup>/(V·s) much higher than the values of 378–450 cm<sup>2</sup>/(V·s) for the films. The Seebeck coefficient for the bamboo-shoot-nanowire structure is in a range of 59–68 µV/K, which is about 15% higher than those for the films (50–61 µV/K). Although maximal power factor of the bamboo-shoot-nanowire structure is 14 times as high as that of the thin film, reaching 0.144 mW/(m·K<sup>2</sup>) at room temperature, this value is still one order of magnitude lower than the previously reported value of 1.58 mW/(m·K<sup>2</sup>) for Cd<sub>3</sub>As<sub>2</sub> single crystal.

Multifunctional pressure/temperature/bending sensor made of carbon fibre-multiwall carbon nanotubes for artificial electronic application

A flexible sensor with excellent pressure, temperature, and bending sensitivity is fabricated based on the conductive skeleton material with hierarchical porous structure. The conductive skeleton material is composed of carbon fibres (CFs) and multiwalled carbon nanotubes (MWCNTs), in which lay perpendicular to each other CFs are used as conductive frames, while MWCNTs are served as bridges to connect the CFs and increase the conductive network formation. Owing to the unique structure and the conductive materials, the as-prepared sensor exhibits a high-pressure sensing performance of 42.7 kPa (0–1 kPa), fast response, relaxation times of<100 ms, wide working range of 0–60 kPa, and high stability over more than 6000 cycles. Furthermore, the fabricated sensor presents a high thermal sensitivity of 2.46 °C−1 between 30 and 40 °C, excellent bending sensitivity of 95.5 % rad−1 in the working range of 0–180°, and great flexibility (over 1000 cycles), demonstrating its potential applications in multifunctional wearable electronics.

Stretchable silver@CNT-poly(vinyl alcohol) films with efficient electromagnetic shielding prepared by polydopamine functionalization

The design of CNT/polymer composite shields is reduced to resolve the issue of CNTs agglomeration which has been tackled by complex and harsh chemical treatments damaging their electrical conductivity and limiting shielding capability. Herein, CNTs were coated with polydopamine (PDA) by exploiting the in-situ spontaneous polymerization of PDA on organic/inorganic surfaces. The PDA functional layer not only resulted in improved CNT dispersion after 2 h-coating time but also served as a platform for subsequent immobilization of silver nanoparticles by the catechol and nitrogen-containing groups of PDA. The well-dispersed CNT and the incorporation of extra silver particles conductive phase resulted in flexible and highly conductive Ag@PDA@CNT-poly(vinyl alcohol) (PVA) films with significantly improved shielding effectiveness of 42.75 dB with respect to pristine CNTs (21 dB). The size of silver particles controlled by PDA polymerization time, the formation of an efficient conductive network and conduction/interfacial polarization-induced loss mechanisms were reasoned to be responsible for dictating the films shielding performance. Such low-key and green approach could be instrumental to developing other metal/CNT polymer films as next-generation lightweight shields for flexible electronics.

Electrical discharge machining of boron carbide-graphene nanoplatelets composites

Boron carbide (B4C) composites containing 0–10 wt.% graphene nanoplatelets (GNPs) were consolidated using hot pressing at 1950 °C for 60 min under 30 MPa in an argon atmosphere. Their electrical discharge machining (EDM) characteristics were evaluated for the first time. Additionally, the effects of GNPs on the microstructure, electrical conductivity, material removal rate (MRR), and surface roughness (Ra) of B4C composites were investigated. The results show that the B4C composite containing 10 wt.% GNPs exhibited the highest electrical conductivity of 4997 S·m−1 because of the formation of GNPs conductive networks. Under a fine machining condition, the MRR of the B4C composite was enhanced by 43.5 % (from 6.55 to 9.40 mm3 min−1) compared with that of monolithic B4C. Furthermore, the Ra decreased to 1.12 μm, which was significantly lower than that of pure B4C (2.44 μm). Scanning electron microscope and energy disperse spectroscopy analysis of the EDM surfaces were used to determine that the main material removal mechanisms for B4C composites with less than 2 wt.% GNPs were spalling and melting. As the GNPs content increased, B4C grain fallout, melting, and evaporation became more dominant. The other mechanisms, including thermal shock and oxidation, are also discussed in detail.

Flexible electronics from hybrid nanocomposites and their application as piezoresistive strain sensors

Poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) is one of the most commonly used styrene-based thermoplastic elastomer (TPE) with unique properties including high resilience and stretchability. In the case of incorporation of conductive fillers into SEBS matrix piezoresistive strain sensors can be fabricated. In this study, conductive flexible polymer nanocomposites were prepared by combination of solvent casting and compression molding by using SEBS matrix with conductive fillers including carbon black (CB), vapor grown carbon nanofibers (VGCNFs), and their mixtures (CB:VGCNF, 1:1) at various filler loadings from 0.5 to 6.5 wt%. Two different SEBS with different block ratios (styrene to ethylene-butylene ratio (S/EB): 13/87 and 19/81) were used in order to observe their effects on morphological, mechanical, thermal, electrical, and electromechanical properties. In all cases, single and hybrid fillers were found to show good dispersion in the matrix. However, polymer type was found significant in terms of mechanical, electrical, and electromechanical properties. SEBS with lower EB content (S/EB:19/81) led to formation of conductive network at lower concentrations for fillers. Although both polymers and all fillers can be used for strain sensors, hybrid composites generally tend to show higher sensitivity. The strain-reversibility of the composites was directly affected by filler type, filler ratio, and polymer type. The most sensitive and stable response was obtained from 3.5 wt% CB-VGCNF filled SEBS with S/EB:19/81 block type. Test conditions (strain %, test speed) were found significant for both mechanical and electromechanical properties. Generally, for both polymers, lower filler ratio, higher strain ratio, and lower test speed resulted in higher sensitivity. • The polymer nanocomposites were prepared by combination of high shear mixing, solvent casting, and compression molding. • CB, VGCNF and CB-VGCNF mixtures and two different SEBS polymers (S/EB: 13/87 and 19/81) were used. • 3.5 wt% CB-VGCNF/SEBS (S/EB:19/81) showed the most sensitive and stable response and GF was between 333-113. • Filler type, filler ratio, polymer type, strain amplitude, and test speed were significant for piezoresistance

Dielectric and electromagnetic interference shielding performance of graphene nanoplatelets and copper oxide nanoparticles reinforced polyvinylidenefluoride/poly(3,4-ethylenedioxythiophene)-block-poly (ethylene glycol) blend nanocomposites

The fabrication of nanocomposites consisting of graphene nanoplatelet (GNP) and copper oxide nanoparticles (CuO) reinforced polyvinylidenefluoride (PVDF)/poly(3,4-ethylenedioxythiophene)-block-poly (ethylene glycol) (PEDOT-block-PEG) blend were done using solution casting technique. The structures and thermal properties of PVDF/PEDOT-block-PEG/GNP/CuO nanocomposites were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC). The morphological analysis done by Scanning electron microscope (SEM) has confirmed the uniform distribution of GNP and CuO throughout the polymer matrix. The dielectric properties and electromagnetic interference shielding efficiency (EMI SE) of produced nanocomposites were also investigated. The maximum values at the low-frequency region (100 Hz and 150 °C), for dielectric constant and dielectric loss obtained, are 34.0 and 9.2, respectively. The maximum EMI SE was observed to be 17 dB for nanocomposites containing 2/20 wt% of GNP/CuO in 12–18 GHz (Ku-band) region and the shielding mechanism was found to be absorption-dominated. The conductive network formation by GNP and CuO in the PVDF/PEDOT-block-PEG blend improved the SE which further emphasizes the potential use of these nanocomposites as an effective EMI shielding material.

Tailorable high-k and negative-k percolation behaviors in PPy/P(VDF-HFP) composites

Polymer-based composites with high permittivity and low loss are highly desirable for many applications such as embedded capacitors and pulse-power. In the meantime, percolating composites with negative permittivity can be promising candidates for metamaterials. In this paper, nanocomposites using conductive polypyrrole nanowires as fillers and poly(vinylidenefluoride-hexafluoropropylene) (P(VDF-HFP)) as matrix were prepared by a solution-casting method. The electrical properties were investigated in detail. Two types of percolation behavior were observed in the composites with increasing PPy content. The permittivity significantly enhanced when the PPy content exceeded high-dielectric percolation threshold (i.e. fhigh-k) due to the large number of microcapacitors formed by PPy fillers and P(VDF-HFP) matrix. With further increasing PPy content, tunable negative permittivity behavior was achieved due to the formation of conductive networks, this phenomenon can be regarded as a negative-dielectric percolation (i.e. negative-k percolation), which can be well described by Drude-Lorentz model. The realization of high permittivity and tunable negative permittivity in PPy/P(VDF-HFP) nanocomposites gives a new and efficient strategy toward high-k materials and random metamaterials.

Low percolation behavior of HDPE/CNT nanocomposites for EMI shielding application: Random distribution to segregated structure

In this study, three different types of nanocomposites with random (r-CPC), segregated (s-CPC) and semi-segregated (ss-CPC) distribution of carbon nanotubes in High Density Polyethylene matrix were fabricated using hot compaction method. Microstructure of nanocomposite samples were observed by Scanning Electron Microscopy, which revealed the formation of carbon nanotubes conductive network at the polymer granule interfaces in segregated structure. While, partial formation of segregated structure was shown in semi-segregated samples. A significant reduction of Young modulus and strength of s-CPC6 and ss-CPC6 compared to r-CPC6 nanocomposite has been correlated to weak interface and voids between HDPE granules in segregated structure. DSC results proved that the crystallinity index of HDPE decreases when the distribution of CNTs in polymer matrix changes from segregated to random structure. Electrical conductivity was measured using four-point probe. Segregated structure samples showed electrical conductivity up to 9 and 5 order of magnitude larger than semi-segregated and random structure nanocomposites, respectively. Nanocomposites follow percolation behavior and applying percolation theory showed a decrease in percolation threshold from 7.1 vol% in r-CPC to 0.099 vol% in s-CPC. Finally, Electromagnetic Interference shielding properties were studied and the highest Shielding Effectiveness (SE) was obtained 21.8 dB in segregated sample at 6 wt% CNTs. While, in random structure the highest EMI SE was 9 dB at 20 wt% CNTs. Absorption and reflection were the dominant shielding mechanisms in segregated and random structure nanocomposites, respectively.

In situ inorganic conductive network formation in high-voltage single-crystal Ni-rich cathodes

High nickel content in LiNixCoyMnzO2 (NCM, x ≥ 0.8, x + y + z = 1) layered cathode material allows high specific energy density in lithium-ion batteries (LIBs). However, Ni-rich NCM cathodes suffer from performance degradation, mechanical and structural instability upon prolonged cell cycling. Although the use of single-crystal Ni-rich NCM can mitigate these drawbacks, the ion-diffusion in large single-crystal particles hamper its rate capability. Herein, we report a strategy to construct an in situ Li1.4Y0.4Ti1.6(PO4)3 (LYTP) ion/electron conductive network which interconnects single-crystal LiNi0.88Co0.09Mn0.03O2 (SC-NCM88) particles. The LYTP network facilitates the lithium-ion transport between SC-NCM88 particles, mitigates mechanical instability and prevents detrimental crystalline phase transformation. When used in combination with a Li metal anode, the LYTP-containing SC-NCM88-based cathode enables a coin cell capacity of 130 mAh g−1 after 500 cycles at 5 C rate in the 2.75-4.4 V range at 25 °C. Tests in Li-ion pouch cell configuration (i.e., graphite used as negative electrode active material) demonstrate capacity retention of 85% after 1000 cycles at 0.5 C in the 2.75-4.4 V range at 25 °C for the LYTP-containing SC-NCM88-based positive electrode.

Comparison of Three Interfacial Conductive Networks Formed in Carbon Black-Filled PA6/PBT Blends.

Interfacial localization of carbon fillers in cocontinuous-structured polymer blends is well-known as a high-efficiency strategy for conductive network formation. However, a comparison with interfacial localization of carbon fillers in sea-island-structured polymer blends is lacking. Here, three types of highly efficient conductive networks formed on the basis of interfacial localization of carbon black (CB) in polyamide 6 (PA6)/poly(butylene terephthalate) (PBT) blends with different blend compositions (80/20, 50/50 and 20/80 vol/vol) were investigated and compared in terms of electrical resistivity, morphology as well as rheological and mechanical properties. The order of the electrical percolation threshold of CB in the three blends is 50/50 < 20/80 < 80/20, which can be attributed to different network structures. The rheological percolation thresholds are close to the electrical ones, confirming the formation of CB networks. The formation mechanisms for the three types of CB network structures are analyzed. All the three types of PA6/PBT-6 vol% CB composites showed improved tensile strength compared with PA6/PBT blends, being in favor for practical applications.

Ultrahigh energy density of polymer nanocomposites containing electrostatically self-assembled graphene oxide and hydrotalcite nanosheets

In this paper, the nanofiller consisting of graphene oxide (GO) and organically modified hydrotalcite (HT) was fabricated via the electrostatic self-assembly and further reduced and incorporated into the polyimide (PI) matrix to prepare superior nanocomposite films with high energy storage density. It was observed by transmission electron microscopy (TEM) that the insulating HT facesheets were attached well onto the GO film to form a stable sandwich structure. The synthesized ternary nanocomposite film (1.0 rGO@HT/PI) showed high breakdown strength of 175.9 kV/mm and ultra-high dielectric constant at 10 kHz (εr = 35.4), about 10 folds more than pure PI (εr = 3.4), resulting in a maximum energy storage density of 4.84 J/cm3. On account of electrostatic self-assembly, HT nanosheets can efficiently reduce the contact area between graphene oxides and inhibit the formation of conductive networks, thus maintaining a high level of breakdown strength and increasing the energy storage density of the nanocomposite films.

Interface Strengthening of PS/aPA Polymer Blend Nanocomposites via In Situ Compatibilization: Enhancement of Electrical and Rheological Properties.

The process of strengthening interfaces in polymer blend nanocomposites (PBNs) has been studied extensively, however a corresponding significant enhancement in the electrical and rheological properties is not always achieved. In this work, we exploit the chemical reaction between polystyrene maleic anhydride and the amine group in nylon (polyamide) to achieve an in-situ compatibilization during melt processing. Herein, nanocomposites were made by systematically adding polystyrene maleic anhydride (PSMA) at different compositions (1–10 vol%) in a two-step mixing sequence to a Polystyrene (PS)/Polyamide (aPA) blend with constant composition ratio of 25:75 (PS + PSMA:aPA) and 1.5 vol% carbon nanotube (CNT) loading. The order of addition of the individual components was varied in two-step mixing procedure to investigate the effect of mixing order on morphology and consequently, on the final properties. The electrical and rheological properties of these multiphase nanocomposite materials were investigated. The optical microscope images show that for PS/aPA systems, CNTs preferred the matrix phase aPA, which is the thermodynamically favorable phase according to the wettability parameter calculated using Young’s equation. However, aPA’s great affinity for CNT adversely influenced the electrical properties of our blend. Adding PSMA to PS/aPA changed the structure of the droplet phase significantly. At 1.5 vol% CNT, a more regular and even distribution of the droplet domains was observed, and this produced a better framework to create more CNT networks in the matrix, resulting in a higher conductivity. For example, with only 1.5 vol% CNT in the PBN, at 3 vol% PSMA, the conductivity was 7.4 × 10−2 S/m, which was three and a half orders of magnitude higher than that seen for non-reactive PS/aPA/CNT PBN. The mechanism for the enhanced conductive network formation is delineated and the improved rheological properties due to the interfacial reaction is presented.

Formation of thermal conductive network in boron nitride/polyvinyl alcohol by ice-templated self-assembly

Ceramic/resin composite is an important thermal management material for electronic packaging. The formation of a thermally conductive network of ceramic fillers in the composite is the key to improving thermal conduction performance. We design a method of ice-templated self-assembly followed by hot pressing to prepare oriented boron nitride/polyvinyl alcohol (BN/PVA) composites. First, the BN/PVA aerogel is made by freezing and then freeze-drying. BN flakes are squeezed by ice crystals to form a 3D network at the ice interfaces. After further removing the gaps between the BN flakes by hot pressing, a dense BN/PVA composite material is obtained. The resulting polymer composite has a thermal conductivity up to 10.04 W m−1 K−1 at h-BN content of 68 wt%. Theoretical analysis shows a low interfacial thermal resistance between BN flakes. This approach can potentially be used in advanced electronic packaging technology, especially in the design of thermal interface materials.

Highly flexible carbon nanotubes/aramid nanofibers composite papers with ordered and layered structures for efficient electromagnetic interference shielding

Efficient electromagnetic interference (EMI) shielding materials with high flexibility, thin thickness, excellent mechanical property, and superior EMI shielding performance are urgently needed for modern electronic devices in areas of aerospace, military, and wireless communication systems. Herein, highly flexible multi-walled carbon nanotubes (MWCNTs)/aramid fibers (ANFs) composite papers with ordered and layered structures were successfully fabricated via a facile vacuum-assisted filtration. The obtained composite papers exhibited high electrical conductivity, outstanding mechanical property, excellent EMI shielding performance of 41.7 dB at a low density of 0.7–0.8 g cm−3 and an average thickness of 0.3 mm. A parameter of the specific shielding effectiveness/thickness (SSE/t) was as high as 2395.8 dB cm2 g−1, which was benefited from the layer structures and the formation of conductive networks inside composite papers. It is expected to provide a promising strategy to prepare high-performance nanocomposite papers for EMI shielding in the field of artificial intelligence or smart and wearable electronics.

Sub‐micron calcium carbonate isolated carbon nanotubes/polyethylene composites with controllable electrical conductivity

AbstractThe dispersion and distribution of carbon nanotubes (CNTs) on/in the polymer composites are greatly affected by the molding technology progress, which results in different electrical conductivity. The uncontrollable electrical conductivity has limited the application of conductive polymer composites, for example, sensor components. In this work, to enhance the dispersion stability of CNTs in polyethylene (PE) matrix, sub‐micron calcium carbonate isolated CNTs (smCaCO3@CNTs) were selected based on the fact that smCaCO3 is much easier to disperse in polymer in comparison with CNTs. This good distribution of CNTs in smCaCO3@CNTs/PE was characterized by transmission electron microscope and Raman mapping. The electrical performance test results show that when 0.5 wt% of CNTs filled in smCaCO3@CNTs/PE, the percolation network begins to form; when CNTs filled increases to 1‐2 wt%, the surface resistance of smCaCO3@CNTs/PE ranges from 106 to 109Ω almost not affected by the molding technology process (compression molding or injection molding). The possible reason is that the isolated CNTs by smCaCO3 in polymer matrix are favorable for the formation of the stable conductive network.

Stimulation of phenanthrene and biphenyl degradation by biochar-conducted long distance electron transfer in soil bioelectrochemical systems

The bioelectrochemical degradation of organic pollutants has attracted considerable attention owing to its remarkable sustainability and low cost. However, the application of bioelectrochemical system (BES) for the degradation of pollutants in soils is hindered by limitations in the effective distance in the soil matrix. In this study, a biochar-amended BES was constructed to evaluate the degradation of organic pollutants. This system was expected to extend the electron transfer distance via conductive biochar in soils. The results showed that biochar pyrolyzed at 900 °C facilitated the degradation of phenanthrene (PHE) and biphenyl (BP) in the soil BES (SBES), reaching 86.4%–95.1% and 88.8%–95.3% in 27 days, respectively. The effective distance of SBESs was estimated to be 154–271 cm away from the electrode, which increased 1.9–3 fold after the addition of biochar. Microbial community and functional gene analysis confirmed that biochar enriched functional degrading bacteria. These findings demonstrate that the promotion of long-distance electron transfer and the formation of soil conductive networks can be achieved by biochar amendment. Thus, this study provides a basis for the effective degradation of for persistent organic pollutants in petroleum-contaminated soils using bioelectrochemical strategy.

Self-healing liquid metal composite for reconfigurable and recyclable soft electronics

Soft electronics and robotics are in increasing demand for diverse applications. However, soft devices typically lack rigid enclosures which can increase their susceptibility to damage and lead to failure and premature disposal. This creates a need for soft and stretchable functional materials with resilient and regenerative properties. Here we show a liquid metal-elastomer-plasticizer composite for soft electronics with robust circuitry that is self-healing, reconfigurable, and ultimately recyclable. This is achieved through an embossing technique for on-demand formation of conductive liquid metal networks which can be reprocessed to rewire or completely recycle the soft electronic composite. These skin-like electronics stretch to 1200% strain with minimal change in electrical resistance, sustain numerous damage events under load without losing electrical conductivity, and are recycled to generate new devices at the end of life. These soft composites with adaptive liquid metal microstructures can find broad use for soft electronics and robotics with improved lifetime and recyclability.

Effects of Al2O3 on Thermal Conductivity of Silicone Rubber

Thermal conductivities of silicone rubber filled with Al2O3 were prepared. Thermal conductivity experimental results obtained were analyzed using the Nielsen and Agari models to explain the effect of Al2O3 filler on the formation of thermal conductive networks. Thermal conductivities increased with the adding of mixed Al2O3 of large and small sizes fillers. The scanning electron microscopy (SEM) showed that it is the optimum particle sizes and quantities that made the filler packing closer, which thus leads to formation of more thermal conductive chains.

The enhancement in dielectric properties for PVDF based composites due to the incorporation of 2D TiO2 nanobelt containing small amount of MWCNTs

Film capacitors can be used as energy storage for fast storage and release energy, but the low energy density limits their applications. In our previous study, we have demonstrated that a small amount of 2D titanium dioxide (TiO2) nanobelts in PVDF could significantly enhance the energy density of these composite films. In order to increase the dielectric constant and energy density of these composites, multi-walled carbon nanotubes (MWCNTs) are introduced into these 2D TiO2 nanobelts obtained during electrospinning, and parallelly oriented along these 2D nanobelts. The shell formed by insulating TiO2 can avoid the formation of conductive network and realize high polarization efficiency. It’s shown that when the ratio of MWCNTs and TiO2 in the composite filler is 1:30, the breakdown voltage of the filler can achieve 478 kV/mm, the polarizability is 8.34 μC/cm2, and the energy density is increased from 2.87 J/cm3 to 17.97 J/cm3 comparing with neat PVDF.