Excellent Conductivity Research Articles

Designing Bilayer Heterostructure Functional Polymer Electrolytes with Interfacial Engineering Strategy for High‐Performance Lithium Metal Batteries

AbstractThe uncontrollable lithium (Li) dendrites growth and complex electrode/electrolyte interface (EEI) problems are hindering the further application of high energy density lithium metal batteries (LMBs) in practice. Herein, a bilayer heterostructure gel polymer electrolyte (BGPE) is designed by directly curing functional boron‐containing monomers on the electrode surface to ensure excellent conductivity while solving the interface problems, achieving durable high voltage resistance and Li dendrites suppression. The unoccupied p‐orbital boron moiety of the 3D crosslinked network in BGPE not only improves the Li+ transference number (0.78), but also enhances the interfacial stability of the Li metal and inhibits the dendrites growth by anchoring PF6− anions and regulating the uniform Li deposition, thus ensuring a long cycle for Li/BGPE/Li cells. In addition, the functional additives tris(trimethylsilyl) phosphite and tris(pentafluorophenyl)borane can preferentially oxidize and decompose to form stable B, F, and Si‐rich EEIs, and effectively regulate the uniform growth of EEI. Thus, the LiNi0.5Co0.2Mn0.3O2/BGPE/Li and LiFePO4/BGPE/Li full cells exhibit stable cycling and excellent rate performance. This work provides a guiding design direction to address the EEI problems for high energy density LMBs.

High-Conductivity and Ultrastretchable Self-Healing Hydrogels for Flexible Zinc-Ion Batteries.

Aqueous zinc-ion batteries are promising candidates for flexible energy storage devices due to their safety, economic efficiency, and environmental friendliness. However, the uncontrollable dendrite growth and side reactions at the zinc anode hinder their commercial application. Herein, we designed and synthesized a dual network self-healing hydrogel electrolyte with zwitterionic groups (PAM-PAAS-QCS), which can be used for the large deformations of flexible devices due to its excellent stretchability (ε = 5100%). The incorporation of zwitterionic groups into the PAM-PAAS-QCS hydrogel electrolyte endows it with high ionic conductivity (33.61 mS/cm), a wide electrochemical stability window, and the ability to suppress zinc dendrite formation and side reactions. Besides, the Zn//Zn symmetric cell with PAM-PAAS-QCS can stably plate and strip zinc for 1500 h at 0.5 mA/cm2, and the Zn//Polyaniline full cell retains 82.4% of its capacity after 1500 cycles at 1 A/g. Additionally, flexible batteries based on both the original and self-healed PAM-PAAS-QCS hydrogel electrolytes demonstrate good cycling stability and stable charge-discharge performance under various bending conditions. This self-healing hydrogel electrolyte with excellent stretchability and high ionic conductivity is expected to pave the way for the development of high-performance flexible energy storage and wearable devices.

Structural, Electronic, and Mechanical Properties of α(U) and α(U-Zr) Alloy Fuels

Uranium-zirconium (U-Zr) alloy fuels have been taken into consideration for fast reactors because of their superior reactor safety, high uranium (U) density, and excellent thermal conductivity. In this paper, the structural and mechanical properties of metallic U and U-Zr alloy fuels are calculated at the atomic level by density functional theory–based calculations with Hubbard U (density functional theory + U) corrections. Several structure-property relations, such as lattice volume, bulk modulus, Young’s modulus, shear modulus, electronic density of states, etc. are calculated for U metal and U-Zr alloy fuels. In addition, the Zr content in metallic U fuel is adjusted from roughly 5 at. % to 15 at. % in order to determine how the Zr content affects the characteristics of U-Zr fuel material. A linear relationship between the volume and Zr concentrations is observed. The concentration of Zr in the fuel affects the mechanical characteristics of U-Zr alloy fuel. It is also observed that the electronic structure of the α-U phase is not changed significantly in the presence of Zr. Our computations provide insight into how U-Zr alloy fuels behave in reactor conditions.

Construction and Performance Study of an Injectable Dual-Network Hydrogel Dressing with Inherent Drainage Function.

With the widespread utilization of moist wound dressings, the extended healing time and increased risk of wound infection caused by excessively moist environments have garnered significant attention. The development of hydrogel dressings that can effectively control the wound moisture level and promote healing is very important. Inspired by the pore-opening perspiration effect of the skin, this study constructed an injectable dual-network hydrogel, CMCS-OSA/AG/MXene, by the composition of a dynamic covalent network of carboxymethyl chitosan and oxidized sodium alginate based on the Schiff base and hydrogen bond network of the thermosensitive low-melting-point agar with the advantage of the upper critical solution temperature (UCST) effect. Under near-infrared (NIR) light stimulation, the CMCS-OSA/AG/MXene hydrogel shows characteristics conducive to rapid removal of wound exudate while maintaining an appropriate moist environment for the wound and excellent antibacterial effects with its photothermal responses. The excellent conductivity of the hydrogel can also promote cell proliferation under external electrical stimulation (ES). Further validation through animal experiments on a full-thickness skin defect model demonstrates the excellent capability of CMCS-OSA/AG/MXene in accelerating wound healing. This work provides an innovative approach to the development of injectable hydrogel dressing materials with inherent drainage functionality and shows a new avenue to wound moisture control and wound healing promotion.

Effect of Microalloying Rare-Earth Nd on Microstructure Evolution and Mechanical Property of Cu Alloy

Cu alloys have been widely used in the manufacture of liners because of their high density, good plasticity, and excellent thermal conductivity. In order to achieve excellent jet stability and penetration performance, it is necessary to further improve the mechanical properties of Cu-based liners. Nevertheless, the simultaneous enhancement of strength and ductility of the Cu alloys remains a huge challenge due to the strength–ductility trade-off phenomenon of metals/alloys. In this study, the microstructure evolution of rare earth Nd-modified Cu alloy and its effect on mechanical properties were investigated using OM, SEM, EBSD, and TEM techniques. The results show that the ultimate tensile strength (218 MPa) and elongation (50.7%) of sample 1 without Nd are the lowest. With increasing Nd content; the tensile strength and elongation of the samples increase; and the mechanical properties of sample 4 are the best, with a tensile strength of 278.6 MPa and elongation of 65.2%. In addition, with the increase in Nd content, not only is the grain size of the Cu-Nd alloy refined, but also the strength and plasticity are improved so that the strength–ductility trade-off phenomenon is improved. The strength improvement is mainly attributed to grain refinement strengthening, dispersion strengthening, and strain hardening. The increase in ductility is mainly related to the improvement of the microstructure heterogeneity by the Nd element.

High-performance fluoride removal by Fe/N co-doped microporous carbon: Mechanism of capacitive deionization with FeNx sites

Fluoride pollution is becoming increasingly serious with industrial growth. Controlling fluoride pollution have become important environmental issues of global concern. Transition metal nitrides are excellent CDI electrode materials due to their excellent conductivity and electrochemical stability. In this study, FeNx/C was synthesized as an electrode material for using the capacitive deionization (CDI) technique to achieve the effective removal of fluoride ions from wastewater. Its high specific surface area (463.278 mg/g) and high capacitance (44.29 F/g) were demonstrated and it had a high adsorption capacity of 158.33 mg/g. FeN3 and FeN4 were used as the main sites as capacitive deionization for removing fluoride from the water by chemisorption and hydrogen bonding. The higher adsorption energy by density functional calculation also indicated that the existence of Fe-N coordination bond effectively improved its electrosorption capacity. This study is beneficial to provide references and research ideas for removing fluoride in the CDI field.

Next-gen strain sensors: Self-healing, ultra-sensitive, lightweight, and durable MWCNT-silicone rubber for advanced human motion tracking

Strain sensors that have flexible wearable forms can be applied in different aspects, such as in soft robotics, human-computer interaction, motion monitoring, and medical treatment process. The main challenge is creating lightweight, flexible sensors with high sensitivity. In this study, we developed flexible strain sensors using a simple sandwich manufacturing method. To achieve this, multi-walled carbon nanotubes (MWCNTs) were chosen for their excellent conductivity, while silicone rubber (SR) provided a flexible and durable substrate. Advanced SEM-EDX and FTIR analyses were conducted to assess the material structure. Furthermore, the electromechanical performance of the sensors was thoroughly evaluated, highlighting their potential in real-world applications. Electromechanical performance evaluation showed that the SR/0.7-MWCNT/SR sensor in the 0–90 % strain range had a sensitivity of 34.47, an increase of 53.35 %, and a linearity of 0.978, an increase of 10 % compared to the SR/0.5-MWCNT/SR sensor. In addition, the sensor has extremely fast response and recovery times of 65 ms and 60 ms, respectively. The sensor is also able to withstand up to 1.200 cycles of stretching, twisting, and bending. The sensor also exhibited good autonomous electromechanical self-healing properties against physical damage. The sensor developed in the present study are proven to be used to detect human movements such as finger bending, wrist, elbow, and knee movements.

In Situ Growth of MoN on Nickel Foam for Highly Efficient Hydrogen Evolution in Alkaline Solution.

Highly efficient, stable, and low-cost hydrogen evolution catalysts are urgently required for water electrolysis. Herein, a method for in situ growth of medium-nitrogen nanosheet MoN catalysts with a large electrochemical surface area on nickel foam (NF) is proposed. The results show that the morphology of the as-prepared catalysts greatly depends on the nitrogen sources and nitridation temperature. The MoN/NF catalyst nitride at 700 °C using melamine as a nitrogen source exhibits a spindle-like morphology consisting of stacked nanosheets, which is conducive to exposing more active sites, thereby increasing the catalyst activity. The N atoms in MoN could adjust the chemical environment of the metal by changing the density of the d-band electron state, which further improves the HER performance. Benefiting from the regulation of Mo charge distribution and exposure to more active sites through N doping and morphological control, the MoN/NF catalyst exhibits superior HER performance with an overpotential of 70 mV at a current density of 10 mA·cm-2, a Tafel slope of 44.3 mV dec-1, and an Rct of 1.83 Ω, indicating high HER catalytic activity, fast kinetics, and excellent conductivity. Theoretical calculations reveal that among the (002), (202), and (200) planes of MoN, the (202) plane exhibits the lowest value of |ΔGH*| (0.47 eV), which is close to that of Pt(111) (0.14 eV). More importantly, MoN(202) also has the smallest work function of 3.58 eV, indicating an enhanced capability to offer electrons. This work develops a strategy to design high-performance and low-cost transition-metal nitride HER catalysts.

Bottom-up stripping of graphene with controlled oxidation behaviors towards supercapacitors energy storage

Due to its distinctive two-dimensional planar structure, room temperature quantum Hall effect, and high strength, graphene has garnered significant interest in the fields of energy storage and conversion. In order to achieve high efficiency in the production of graphene, electrochemical peeling has been extensively investigated. Nevertheless, the intermolecular forces between graphite layers are disrupted during ion intercalation in solution, leading to inconsistent bonding forces and low yields. In order to address the issues above, this study introduces a novel bottom-up electrochemical peeling method, wherein graphite expansion occurs above the electrolyte. By preventing contact between the peeled graphene and the electrolyte, the oxidation of graphene is significantly minimized, resulting in a substantial yield of 88 %. At the current density of 1.0 A g−1, the Go-QAS displayed 225.5 F g−1, and kept about 220.2 F g−1 after 500 cycles. The well-designed bottom-up peeling process leads to graphene nanosheets with reduced structural degradation, high purity, and excellent conductivity. This technique is expected to introduce innovative concepts for the field.

Synergistic promotion of reaction kinetics for LiPSs at high loadings by interfacial built-in electric field and sulfur vacancies of ternary heterostructure for high-performance Li-S batteries

The practical application of lithium-sulfur batteries is significantly impeded by the chaotic migration of lithium polysulfides, sluggish redox-reaction kinetics, and pronounced shuttle effect. Herein, a ternary heterostructure (MoS2-x/MoO2/CoP) is developed with a spontaneous built-in electric field (BIEF) and enriched sulfur vacancies. This heterostructure comprises MoS2-x, which has a high adsorption capability and work function; CoP, noted for its low work function and potent catalytic properties; and MoO2, which features a work function between that of MoS2-x and CoP and serves as a bridge with excellent electronic conductivity. An appropriate combination of the catalyst and adsorbent with sulfur vacancies controls the direction of the BIEF, realizing the “adsorption-directed migration-catalytic” reaction mechanism for sulfur species. Specifically, the synergetic effect of the BIEF and sulfur vacancies enhances electron migration from CoP to MoS2-x, which improves the lithium polysulfide (LiPSs) trapping and accelerates the directional migration of LiPSs to CoP, thereby enabling the efficient catalytic conversion of sulfur species. Consequently, batteries equipped with MoS2-x/MoO2/CoP interlayers that contain sulfur vacancies demonstrate an ultrahigh initial specific capacity of 1356.2 mA h g−1 at 0.2 C, maintaining a capacity of 708.3 mAh g−1 after 1000 cycles at 2 C. Even with sulfur loading increased to 7.13 mg cm−2, these batteries display an initial specific capacity of 7.2 mAh cm−2. This work provides a feasible approach for the rational design of vacancy-containing ternary heterostructure catalysts for commercial lithium-sulfur batteries.

Gain performance and thermal effects of Nd:Glass and Nd,Y:SrF2 crystal

The gain performance and thermal effects of Nd:glass (N31) and Nd,Y:SrF2 crystal are investigated and compared. The results show that, under the same pump conditions, Nd,Y:SrF2 can provide a small-signal gain similar to that of N31. The main advantages of Nd,Y:SrF2 are its weaker thermal effects and greater thermal-fracture limitations compared with those of N31. In this paper, the two gain media are compared in the form of rods whose diameter is 5 mm and length is 60 mm. The small-signal gain coefficients of N31 and Nd,Y:SrF2 are 1.39 and 1.46, respectively, at a pump energy of 1.5 J/1 Hz. The pump energy is set at 1.5 J/8 Hz to experimentally investigate their thermal effects. The thermal wavefront of N31 is 0.987λ at a repetition rate of 10 Hz, whereas that of Nd,Y:SrF2 is 0.679λ. In thermal destructive experiments, N31 fractured at an average pump power of 15 W (1.5 J/10 Hz), whereas Nd,Y:SrF2 fractured at a higher power of 27 W (1.5 J/18 Hz) owing to its excellent thermal conductivity, which is 7.28 times that of N31. These results indicate the potential of Nd,Y:SrF2 crystal as a gain medium for high-repetition-rate laser amplifiers.

Janus-Architectured Lithium Replenishment Separators Boosting Longevity of Anode-Free Lithium Metal Batteries.

Addressing the issue of inactive dead lithium deposition on the anode side remains a significant challenge for anode-free lithium metal batteries. While lithium compensation techniques can mitigate lithium depletion, directly introducing lithium compounds into the cathode material may degrade the electrode structure. Here the design and fabrication of a novel lithium replenishment separator (LRS) using a lithium compensation agent of Li2C4O4 is reported. The electrospun LRS demonstrates excellent ionic conductivity of 1.82 mS cm-1 and a high Li+ transference number of 0.51. Such a functionalized LRS not only provides additional active lithium for anode-free lithium metal batteries but also promotes uniform deposition of lithium metal. Compared with conventional polyolefin-based separators, the LRS effectively boosts LiFePO4||Cu anode-free batteries with enhanced cyclability. These results suggest this LRS strategy can find promising applications in next-generation anode-free batteries with high energy densities.

Theoretical study of point defects on transport properties in metallic interconnections

During the line width reduction, electron scattering caused by various defects in metal interconnects increases dramatically, which causes leakage or short circuit problems in the device, reducing device performance and reliability. Point defects are one of the important factors. Here, using density functional theory and non-equilibrium Green's function methods, we systematically study the effects of point defects on the transport properties of metals Al, Cu, Ag, Ir, Rh, and Ru, namely vacancy defects and interstitial doping of C atom. The results show that the conductivity of all systems decreases compared to perfect systems, because defects cause unnecessary electron scattering. Since the orbital hybridization of the C atom with the Al, Cu and Ag atoms is stronger than that metals Ir, Rh and Ru, the doping of C atom significantly reduces the conductivity of metals Al, Cu and Ag compared to vacancy defects. In contrast, vacancy defects have a greater impact than doping on the transport properties of metals Ir, Rh and Ru, which is mainly attributed to the larger charge transfer of the host atoms around the vacancies caused by lattice distortion. In addition, metal Rh exhibits excellent conductivity in all systems. Therefore, in order to optimize the transport properties of interconnect metals, our work points out that the doping of impurity atoms should be avoided for metals Al, Cu and Ag, while the presence of vacancy defects should be avoided for metals Ir, Rh and Ru, and Rh may be an excellent candidate material for future metal interconnects.

Two-dimensional p-n heterojunctions of black phosphorus nanosheet-sensitized α-MoO3 nanoflake for low-temperature chemiresistive NH3 recognition

Of diverse NH3 gas-detection strategies applied in the fields of individual healthcare and industrial production, chemiresistive gas sensors gain the most popularity owing to the superior merits of low cost, convenient signal processing and high sensitivity. However, severe challenges still exist such as elevated operation temperature (>200 °C), limited sensitivity and unsatisfactory selectivity especially under low-concentration and high-humidity conditions. To overcome these hindrances, a sensing layer of black phosphorus nanosheets (BP)-modified α-MoO3 nanoflakes was prepared in this work. After subtle optimization of ingredient composition and operation temperature, the composite sensor S2 could recognize NH3 gas with the concentration spanning from 0.4 to 25 ppm at 40 °C. In particular, a larger mean response (27 % vs. ∼ 2.3 %) with a response/recovery speed of 275/388 s toward 10 ppm NH3 and lower detection of limit (LoD, 0.4 ppm vs. 10 ppm) was achieved with respect to pure BP counterpart. In addition, excellent repeatability, selectivity, long-term stability and humidity-tolerant features were demonstrated for Sensor S2. The improved sensing performance after α-MoO3 incorporation was primarily ascribed to abundant p-n heterojunctions, excellent conductivity of BP and hydrophilic MoO3 that mitigated the water corrosion effect on susceptible BP nanosheets. This work offers an alternative strategy for sensitive and low-temperature NH3 detection, and well cater for the demanding requirements of high sensitivity and low-power consumption in the field of novel gas sensors applicable in the future Internet of Things and exhaled breath-oriented medical diagnosis.

Bio‐inspired graphene oxide/epoxy coating with ordered stacking for anticorrosion/wear protection of Mg alloy

AbstractThe random arrangement of graphene oxide (GO) nanosheets within the organic coating forms a conductive network, thereby accelerating galvanic corrosion and exacerbating metal deterioration. Inspired by ordered layered structure of natural nacre, this study has successfully fabricated a biomimetic GO/epoxy coating on Mg alloy to prevent corrosion and reduce wear. By polymerizing polyaniline (PANI) and dopamine (PDA) on the GO, GO/PANI/PDA sheets with good dispersibility and impermeability are obtained. Subsequently, the bio‐inspired coating (I‐GO/PANI/PDA‐WEP) with “nacre‐like” structure is prepared via alternately spraying GO/PANI/PDA layers with epoxy layers. The anisotropic electrical conductivity of the coating is derived from the ordered distribution of GO/PANI/PDA layers to the Mg substrate, which can conduct electricity more efficiently in‐plane while suppressing longitudinal electron transport. The enhanced physical barrier effect by the “nacre‐like” structure and the electron suppression effect can improve anticorrosion performance. The coating reduces the corrosion rate by 6.3 × 105 times in comparison to Mg alloy. Moreover, this coating shows excellent wear resistance, which protects Mg alloy from friction and wear with a reduction in wear rate by approximately 96%. This bio‐inspired approach offers a unique strategy for fabricating GO composite coatings with exceptional performance.Highlights The corrosion/wear resistance of I‐GO/PANI/PDA has greatly improved. GO/PANI/PDA coating exhibits excellent anisotropic conductivity. Galvanic corrosion is inhibited due to the addition of GO/PANI/PDA. “Nacre‐like” structure shows high labyrinth effect. The ordered orientation of GO/PANI/PDA suppresses out‐plane electron transport.

Harnessing carboxymethyl cellulose as eco-binder to transform polyester textile waste into high-performance fire-resistant thermal insulation panels

This study aims to investigate the applicability of carboxymethyl cellulose (CMC) as a binder in insulating panels made from polyester textile waste (PTW), which is the most produced textile waste worldwide. This combination addresses the pressing need to recycle a widely manufactured material while introducing CMC as an environmentally friendly solution for elaborating panels with excellent thermal insulation and fire resistance. The composite panels were manufactured using compression molding process. The resulting thermal insulation panels demonstrate excellent thermal conductivity values, ranging from 0.0499 to 0.0514 W/m.K, comparable to established insulation materials. Panels with increased CMC content show remarkable mechanical strength, with compressive strengths of 217 kPa and 351 kPa for samples S4 and S5, respectively, and a flexural strength of 1.58 MPa for sample S5. This emphasizes that CMC as a binder helps distribute stresses more evenly across the composite, leading to higher strength and stiffness. Furthermore, employing CMC in the composite preparation confers exceptional resistance to flame propagation, namely, samples S4 and S5 exhibited immediate self-extinguishing properties and resistance to flame propagation. Accordingly, the mechanism behind CMC ability to resist flame propagation was investigated. Despite the composite's remarkable characteristics, its water sensitivity remains a disadvantage. Therefore, this shortcoming has been addressed highlighting several strategies that can be employed to mitigate CMC sensitivity to water including applying a waterproof coating to improve the composite humidity and water resistance increasing its overall durability.

Microfluidic Wearable Electrochemical Sensor Based on MOF-Derived Hexagonal Rod-Shaped Porous Carbon for Sweat Metabolite and Electrolyte Analysis.

Wearable sensors enable the noninvasive continuous analysis of biofluid, which is of great importance for healthcare monitoring. In this work, a wearable sensor was seamlessly integrated with a microfluidic chip which was prepared by a three-dimensional printing technology for noninvasive and multiplexed analysis of metabolite and electrolytes in human sweat. The microfluidic chip could enable rapid sampling of sweat, which avoids the sweat evaporation and contamination. Using a Zn metal-organic framework as a sacrificial template, the hexagonal rod-shaped porous carbon nanorod (PCN) with high porosity, a large specific surface area, and excellent conductivity was synthesized and exhibited the robust electrocatalytic ability of uric acid (UA) oxidation. Therefore, the PCN-based sensor showed high sensitivity and good selectivity of UA with a wide linear range of 10-200 μM and a low detection limit of 4.13 μM. Meanwhile, the potentiometry-based ion-selective electrode was constructed for detection of pH and K+, respectively, with good sensitivity, selectivity, reproducibility, and stability. In addition, the testing under different bending states demonstrated that mechanical deformation had little effect on the electrochemical performance of the wearable sensors. Furthermore, we evaluated the utility of the wearable sensor for multiplexed real-time analysis of UA, pH, and K+ in sweat during aerobic exercise, and the effect of the amount of consumed purine-rich foods on uric acid metabolite levels in sweat and urine was further investigated. The relationship between urine UA and sweat UA was obtained. Overall, this wearable sensor enables multiple electrolyte and metabolite analysis in different noninvasive biofluids, suggesting its potential application in personalized disease prevention.

Facile Preparation of Three-Dimensional Cubic MnSe2/CNTs and Their Application in Aqueous Copper Ion Batteries.

Transition metal sulfide compounds with high theoretical specific capacity and excellent electronic conductivity that can be used as cathode materials for secondary batteries attract great research interest in the field of electrochemical energy storage. Among these materials, MnSe2 garners significant interest from researchers due to its unique three-dimensional cubic structure and inherent stability. However, according to the relevant literature, the performance and cycle life of MnSe2 are not yet satisfactory. To address this issue, we synthesize MnSe2/CNTs composites via a straightforward hydrothermal method. MnSO4·H2O, Se, and N2H4·H2O are used as reactants, and CNTs are incorporated during the stirring process. The experimental outcomes indicate that the fabricated electrode demonstrates an initial discharge specific capacity that reaches 621 mAh g-1 at a current density of 0.1 A g-1. Moreover, it exhibits excellent rate capability, delivering a discharge specific capacity of 476 mAh g-1 at 10 A g-1. The electrode is able to maintain a high discharge specific capacity of 545 mAh g-1 after cycling for 1000 times at a current density of 2 A g-1. The exceptional electrochemical performance of the MnSe2/CNTs composites can be ascribed to their three-dimensional cubic architecture and the 3D CNT network. This research aids in the progression of aqueous Cu-ion cathode materials with significant potential, offering a viable route for their advancement.

Synthesis of perylene‐PEO hyperdispersants for aqueous graphene dispersion

AbstractGraphene, with excellent thermal conductivity, electrical and corrosion shielding performance has great application potential in the fields of heat dissipation coating, conductive agent and anticorrosion composite coatings. However, due to its large specific surface area, resulting strong aggregation behavior limits its application. Herein, the hyperdispersants with perylene anchoring groups are synthesized through the amidation coupling reaction between diacid anhydride and polyetheramine. The branching degree and length of hydrophilic chains on hyperdispersant are revealed to be the very important factors to affect the dispersion stability of aqueous graphene dispersion. The hyperdispersant with a single hydrophilic chain and the molecular weight 2000 of polyetheramine has the excellent dispersal activity discovered by Rheology, particle size distribution and Raman measurements. The possible mechanism is the strongest anchoring effect of perylene on graphene surface and thus achieving in best effective spatial exclusion stabilization effect of hydrophilic chains.

A Molecular Dynamics-Based Approach to Study the Effect of Covalently Bonded Modified Graphene on the Heat Transport Properties of Graphene/Natural Rubber Composite Material Interfaces.

Due to its excellent thermal conductivity, graphene can have great potential in the thermal conductivity of rubber composites. However, the interfacial thermal resistance between graphene and rubber severely hinders this application. In this work, molecular dynamics methods were used to study the interfacial thermal transport of carboxylated, aminated, hydroxylated, and oxy-bridged graphene in rubber composites. The results showed that the covalently bonded modified graphene significantly improved the thermal conductivity of the composites, with increases in thermal conductivity of 156.56%, 86.83%, 60.71%, and 44.28% and decreases in interfacial thermal resistance of 41.84%, 34.72%, 31.86%, and 16.74%, respectively. By calculating the phonon densities of states of different functionalized graphenes, it was found that covalently bonded functional groups increased the phonon match between graphene and natural rubber. However, when the degree of functionalization was greater than 11.96%, the phonon match was maintained at a stable value, which was why the covalently bonded modified graphene could significantly reduce the interfacial thermal resistance. Moreover, the graphene modified by covalent bonding was more uniformly distributed inside the natural rubber. The results of this study provide important theoretical guidance for preparing graphene/natural rubber composites with high thermal conductivity.