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Modern electronics and electric power grids require high performance polymer-based dielectric nanocomposites. To realize large-scale applications, the energy density of nanocomposites needs to be further increased. Here, we demonstrate a remarkable improvement in energy density of poly(vinylidene fluoride) (PVDF) matrix upon the incorporation of high-κ Bi4.2K0.8Fe2O9+δ (BKFO) nanobelts. High aspect ratio BKFO nanobelts can enhance the Young's moduli of the nanocomposites and increase the path tortuosity of electrical trees, which are favorable for increasing the breakdown strength of the system. Thus, the dielectric constant and breakdown strength increase simultaneously at a low volume fraction (0.35 vol%) of BKFO nanobelts, and an ultrahigh recoverable energy density of 25.4 J/cm3 is achieved. These results provide a strategy to develop high performance flexible high-energy-density devices. Keywords: Dielectric nanocomposite, Energy storage, Nanobelt, Breakdown strength

Rare earth elements (REEs) of low concentration are usually beneficial to plant growth, while they are toxic at high concentrations. The effects of treatment with lanthanum (La) (10 and 20 μM), cerium (Ce) (10 and 20 μM), and terbium (Tb) (10 and 20 μM) on seedling growth of alfalfa (Medicago sativa L.), which is one of the most important perennial leguminous forages in the world, were studied. The results showed that all three REE treatments quickened the germination of seeds. The length of shoot under La (20 μM) treatment was significantly shortened (P < 0.05). In addition, treatment with La, Ce, and Tb had a “hormesis effect” on root length. There was a significant decrease in chlorophyll content on treatment with the three REEs, and the degree of decline was in the order of La < Ce < Tb, under the same concentration. In vitro experiments and quantum chemical calculations were further performed to explain why the treatments with REEs reduced the chlorophyll content. In vitro experiments showed that La, Ce, and Tb treatments reduced the absorbance of chlorophyll, and the decrease followed in the order of La > Ce > Tb. Quantum chemical calculations predicted that the decrease in absorption intensity was caused by the reactions between La, Ce, Tb, and chlorophyll, which formed lanthanides-chlorophyll; and there were five types of stable lanthanides-chlorophyll. In conclusion, the decrease in chlorophyll content on treatment with REEs was caused by the change in chlorophyll structure.

Inorganic nanomaterials exhibit superior friction-reduction and anti-wear properties in oils. In this study, 2D layered α-zirconium phosphate (α-ZrP) nanosheets intercalated with different amines have been synthesized to study their dispersion stabilities in lubricating oil and tribological applications. The intercalated amines should be sufficiently long and lipophilic to provide stabilization to α-ZrP nanosheets in mineral oil. The results of tribological tests illustrate that with the addition of well-dispersed nanosheets, the coefficient of friction (COF) and pin volume loss reduce by ~47% and 75%, respectively. The excellent dispersion stability enables the nanosheets to flow into the contact area at the beginning, and thereby protect the rubbing surface. A reduction in the van der Waals forces between the adjacent layers induced by the intercalated amines transforms the friction between adjacent layers from pin disk to sliding, leading to a decrease in the COF under hydrodynamic lubrication. The study provides a new method to enhance the tribological properties via tuning the dispersion stabilities of nanomaterials in oils.

Two-dimensional layered α-zirconium phosphate (ZrP) nanoplatelets with two distinguished sizes but similar aspect ratio were directly incorporated into polyamide 66 (PA66) by simple melt processing without using any surfactants. Through the electron microscopy analysis, the large ZrP nanoplatelets with ~ 1.33 μm in size and ~ 5.8 in aspect ratio exhibit a uniform dispersion in PA66 matrices at the filler loading up to 3 wt%, while the small ZrP nanoplatelets with an average size of ~ 230 nm and aspect ratio of ~ 6.2 tend to form large-scale aggregates in PA66 even at 1 wt% loading. Tensile testing results illustrate that the large ZrP nanoplatelets exhibit a better reinforcement effect in PA66 than the small ones. With the incorporation of 3 wt% large ZrP nanoplatelets, the PA66 nanocomposites exhibit an increase of ~ 10% in tensile modulus and ~ 14% in tensile strength as compared with the pure PA66. Pin-on-disc wear tests illustrate that the nanocomposites containing large ZrP nanoplatelets have better anti-wear properties than those prepared with small ZrP nanoplatelets. In specific, the PA66 nanocomposites containing 1 wt% large ZrP nanoplatelets show a ~ 43% decrease in friction coefficient and a ~ 59% reduction in the wear rate under the test condition of 40 N in load and 0.6 m/s in velocity. The mechanisms that are responsible for the mechanical and tribological enhancements in the PA66/ZrP nanocomposites have also been discussed.

Hydrophobic graphite fluoride (GrF)-reinforced epoxy coatings are fabricated on steel substrate with a simple, solventless, and surfactant-free approach. The contact angle can be enhanced from 72° ...

In this paper, the correlation of the interfacial molecular array behavior of sugar-based green surfactant dodecyl maltoside DDM, and its apparent foam properties was investigated by molecular dynamics simulation and quantum chemical calculation as well as experimental methods. A common nonionic surfactant nona-ethylene glycol dodecyl ether C12E9, which has same hydrophobic tail and similar O atom number in headgroup with DDM, was studied as a reference. It was found that, not only the array behaviors of hydrophilic groups of DDM and C12E9 at the air-water interface, but also the intermolecular interactions were quite different. The simulation finding agreed well with the experimental results, by which how the interfacial molecular array behavior of the two types of nonionic surfactants affect the foam properties was revealed, and the application potential of DDM being used as foam stabilizer under diverse harsh conditions, such as high salinity, high temperature, strong acid and alkali, was presented, which should be quite meaningful.

The developments of next-generation electric power systems and electronics demand for high temperature (∼150°C), high energy density, high efficiency, scalable and low-cost polymer-based dielectric capacitors which are still scarce. Here, the nanocomposites based on polyimide-poly(amic acid) copolymers with a very low amount of boron nitride nanosheets are designed and synthesized. Under the actual working condition in hybrid electric vehicles of 200 MV m-1 and 150°C, a high energy density of 1.38 J cm-3 with an efficiency of higher than 96% is achieved. This is about 2.5 times higher than the room temperature energy density (∼0.39 J cm-3 under 200 MV m-1 ) of the commercially used biaxially oriented polypropylene, the benchmark of dielectric polymer. Especially, the energy density and efficiency at 150°C show no sign of degradation after 20000 cycles of charge-discharge test and 35 days' high-temperature endurance test. This research provides an effective and low-cost strategy to develop high-temperature polymer-based capacitors. This article is protected by copyright. All rights reserved.

In the wide application of aqueous foam, creating abundant foam and processing appropriate foaming control are both essential, depending upon the actual situation; the latter process is not only harder to achieve, but also more complicated to comprehensively understand on the molecular level. In this paper, a type of natural flavor oil, carvone, was solubilized in a micelle solution of sodium dodecyl sulfate (SDS) to study the effect on the foaming properties. The foamability and foam stability of the swollen micelle solutions were experimentally characterized, and the molecular behavior of the surfactant and oil molecules before, during and after the foaming process were investigated. It was found that the solubilized carvone co-adsorbed with SDS at the gas/water interface and caused a prominent effect on the foam film stability in several approaches, thereby making the flavor oil a possible foam controller that would not inhibit foam formation, but could eliminate foam efficiently once foam was undesired. Interestingly, it was found that the release of flavor in the foaming process was promoted. Detailed discussion of the interfacial behavior of carvone and the effect on the foaming properties of surfactants in different stages of foam may provide a theoretical foundation for exploring green and smart approaches in achieving foaming control.

The widely performance of surfactants is closely related to their interfacial activity, which is essentially determined by the molecular array behaviours at the interface, of which the studies are significance for clearly understanding their structure-performance relationships. In this paper, the detailed molecular array behaviours of green surfactant alkyl polyglycoside (APG) and the mixed systems with other types of surfactants on oil/water interface have been studied using molecular dynamics simulations, and the key theoretical principle was confirmed by quantum chemistry calculations. It was found that the hydrophilic maltose ring head groups of decyl polyglycoside (C10-APG) are prone to lie flatly at the oil–water interface, the steric hindrance results in the low interfacial density, which critically determines the limit of the interfacial activity. The interfacial adsorption behaviours of the binary mixtures of C10-APG and SDS or DATB and the ternary mixtures of C10-APG, SDS and DATB were studied in detail, how the efficient synergism effect could be achieved for the mixture to get super high interfacial activity was discussed. This study provides a strategy to reveal how the molecular interfacial behaviours determine the key interfacial characteristics of the novel surfactants, which might provide help to promote their applications.

The Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to investigate the adsorption and diffusion properties of CH4 and CO2 in montmorillonite slit-nanopor...

Full exploitation and utilization of the unconventional reservoirs of shale gas have become a central issue due to the increasing worldwide energy demand. Enhancing shale gas recovery by injecting CO2 is a promising technique that combines shale gas extraction and CO2 capture and storage (CCS) perfectly. In this study, a kerogen-based slit-shaped pore with a width of ∼21 A was constructed by two kerogen matrices, and the grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to investigate the adsorption and diffusion properties of CH4 and CO2 in the kerogen matrix and slit nanopores and explore the displacement efficiency of the residual CH4 by CO2 in kerogen slit nanopores. The adsorption energy of CH4 and CO2 on the kerogen fragment surface and the isosteric heat of CH4 and CO2 in kerogen slit nanopores were examined to demonstrate the competitive adsorption of CO2 over CH4 in kerogen slit nanopores, and the different intensity of interactions between the CH4 and CO...

Polymer-based dielectric materials play a key role in advanced electronic devices and electric power systems. Although extensive research has been devoted to improve their energy-storage performances, it is a great challenge to increase the breakdown strength of polymer nanocomposites in terms of achieving high energy density and good reliability under high voltages. Here, a general strategy is proposed to significantly improve their breakdown strength and energy storage by adding negatively charged Ca2 Nb3 O10 nanosheets. A dramatically enhanced breakdown strength (792 MV m-1 ) and the highest energy density (36.2 J cm-3 ) among all flexible polymer-based dielectrics are observed in poly(vinylidene fluoride)-based nanocomposite capacitors. The strategy generalizability is verified by the similar substantial enhancements of breakdown strength and energy density in polystyrene-based nanocomposites. Phase-field simulations demonstrate that the further enhanced breakdown strength is ascribed to the local electric field, produced by the negatively charged Ca2 Nb3 O10 nanosheets sandwiched with the positively charged polyethyleneimine, which suppresses the secondary impact-ionized electrons and blocks the breakdown path in nanocomposites. The results demonstrate a new horizon of high-energy-density flexible capacitors.

The synthetic α-zirconium phosphate (ZrP) modified by tetra-n-butylammonium hydroxide (TBA+OH−) was used to fabricate highly transparent and superhydrophilic coating on glass substrate through a facile and effective approach. The influence of molar ratio between TBA+OH− and ZrP on the surface topographical morphology, as well as the hydrophilicity and transparency of coating was explored. It was found that, the higher concentration of TBA+OH− is, the better surface wettability and light transmission performance are. With more introduction of TBA+OH−, more TBA+ ions can be intercalated into the ZrP interlayers to form exfoliated nanoplatelets, which are able to continuously cover the whole glass substrate as revealed by scanning electron microscopy and atom force microscopy. As a result, the contact angle of the prepared coatings can reach to ~4.5° at 400 ms and ~0° within 1 s. The completely exfoliated structure of ZrP nanoplatelets and high surface charge density provided by TBA+ ions make a great contribution to the highly transparent and superhydrophilic coatings on glass substrates. The detailed mechanisms on fabricating high-performance superhydrophilic coatings on glass substates by TBA+OH− modifying ZrP nanoplatelets are carefully elaborated.

In this study, styrene/heptadecafluorodecyl acrylate (St–HFDA) copolymers of different compositions were synthetized for the purpose of thickening supercritical carbon dioxide (SC-CO2). The cloud point pressures of the copolymer–CO2 mixtures and the thickening effects of these copolymers for SC-CO2 were measured. Molecular dynamics (MD) simulations were used to evaluate the intermolecular interactions and microstructures of polymer–CO2 systems, the copolymer–CO2 interaction energy, cohesive energy density (CED), solubility parameter, equilibrium conformations and radial distribution functions (RDFs) were obtained, which provided useful information for microscopic understanding on the thickening capability of copolymers in SC-CO2. It was found that all the synthesized St–HFDA copolymers induced greater viscosity enhancements of SC-CO2 compared to poly(Heptadecafluorodecyl acrylate) (PHFDA), and π–π stacking of the Styrene (St) groups played a key role in thickening SC-CO2. On one hand, the introduction of the St groups into PHFDA weakened the CO2-philicity of the polymers by reducing the polymer–CO2 interaction and increasing polymer–polymer interactions, resulting in higher cloud point pressure in SC-CO2 compared to PHFDA. On the other hand, the increase of the polymer–polymer interaction via π–π stacking provided an associative force to thicken SC-CO2. The subtle relationship between the copolymer composition and thickening abilities of the copolymers in SC-CO2 were evaluated and the optimum styrene molar ratio was determined. It can be concluded that the content of the CO2-philic HFDA groups and the CO2-phobic St groups in the copolymers should be optimized to achieve the balance between the solubility and the thickening capability.

Nylon6 nanocomposites containing pristine layered α-zirconium phosphate (ZrP) nanoplatelets of various sizes have been fabricated by a simple and direct melt-compounding method without adding intercalation or exfoliation agents. Owing to the excellent compatibility between the nanofillers and Nylon6, the pristine ZrP nanoplatelet nanocrystallites were well dispersed and homogeneously distributed into the polymer matrices during the melt processing, but still maintained their original layered state as observed by scanning electron microscopy and X-ray diffraction. Tensile testing and dynamic mechanical analysis on the Nylon6/ZrP nanocomposites illustrate that the size and concentration of the pristine ZrP nanoplatelets have a profound effect on the mechanical properties of such prepared polymer nanocomposites. The improvement of the mechanical reinforcement for the Nylon6 nanocomposites does not show a steady increase with the increase in the size and concentration of the embedded pristine ZrP nanoplatelets, but displays the maximum for the pristine ZrP nanoplatelets with a size ranging from 600 nm to 800 nm at a concentration of ∼3.0–5.0% in the polymer matrices. The mechanisms that are responsible for the mechanical reinforcement of thermoplastic polymer matrices by the embedded pristine ZrP nanoplatelets, as well as their comparisons with corresponding epoxy nanocomposites, are also discussed.

Chemical mechanical polishing (CMP) is the most effective technology for the global and local planarization of metal surfaces. In this study, an environment-friendly and highly efficient CMP slurry for aluminum alloy is prepared by using 2D layered zirconium phosphate (ZrP) platelets and alumina (Al2O3) particles as hybrid abrasives, polyethylene glycol (PEG) as dispersant, hydrogen peroxide (H2O2) as oxidant and sodium dodecyl sulfate (SDS) as corrosion inhibitor. Using the optimized CMP slurry, surface roughness (Ra) of aluminum alloy is decreased from ~200 nm to ~13 nm and material removal rate (MRR) can be increased from 150 nm/min to 300 nm/min. The addition of ZrP platelets can improve the stability and dispersion of the Al2O3 abrasives due to the PEG-induced hydrogen bonding interactions between the used hybrid abrasives. Moreover, the X-ray photoelectron spectroscopy (XPS) and electrochemical analysis reveal that adjusting the concentrations of H2O2 and SDS in the CMP slurry would help to achieve an excellent balance between the chemical corrosion and mechanical removal. The use of binary hybrid abrasives in CMP slurries provides a novel route for the efficient planarization of aluminum alloy and also sheds light on precise polishing for metallic and non-metallic materials with desired surface requirements.

Polylactic acid (PLA) is a promising biodegradable polyester, however, the brittle nature of PLA restricts its applications. In this study, PLA is reinforced by artificially cultured diatom frustules (DFs) to prepare high-performance and biodegradable polymer composites via melt blending. Interpenetrating structure can be observed between DFs and PLA by scanning electron microscope (SEM) due to the porous nature of diatom. Both X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis reveal that well-dispersed DFs can act as a nucleating agent to increase the crystallinity of the α-crystal in PLA, but decrease its cold crystallization temperature (Tcc). Tensile tests show that both strength and ductility of PLA can be enhanced simultaneously by incorporation of a few percent of DFs. Dynamic mechanical analysis (DMA) indicates that DFs can increase the storage modulus and maintain the glass transition temperature of PLA. Our study illustrates the promise of utilizing artificially cultured diatom frustules as biomass-based reinforcing fillers for preparing high-performance fully-biodegraded polymeric materials for green and sustainable applications.

Exploring simple synthesis method of high-performance sodium-ion batteries (SIBs) electrode materials has always been highly concerned in large-scale energy storage technology filed. Here, ultrathin two-dimensional (2D) FexCo1-xSe2 nanosheets as anode material for SIBs are successfully synthesized by one-step solvothermal method. The average thickness of Fe0·08Co0·92Se2 nanosheets is approximately 3.08 nm, which is about equivalent to the thickness of six b-axis crystal cells. When employed as anode for SIBs, Fe0·08Co0·92Se2 nanosheets display a high initial discharge specific capacity of 679.8 mAh/g, a high initial coulombic efficiency of 85.5% and superior reversible specific capacity of 510.4 mAh/g at 1 A/g. Simultaneously, Fe0·08Co0·92Se2 also exhibits an enhanced rate capability (480.0, 460.0, 435.1 mAh/g at 0.2, 2, 4 A/g respectively) and outstanding cycling stability at relatively large current density (397.0 mAh/g at 4 A/g after 1000 cycles). The excellent Na-ion storage performance of FexCo1-xSe2 nanosheets could be ascribed to the abundant electrochemical active sites and shorten ion transfer tunnels provided by this ultrathin 2D structure and bimetallic ion synergistic effect by heteroatom doping. Noticeably, the capacitive contribution may play the key role in the admirable rate capability through electrochemical kinetics analysis of Fe0·08Co0·92Se2 nanosheets. Therefore, this work presents a simple preparation of ultrathin 2D selenide nanosheets and an effective low-cost regulation strategy for improving Na-ion storage performance.

Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to investigate the adsorption and diffusion properties of CH4 and CO2 in calcite slit nanopores with a pore width of ∼22 A. It was found that, in contrast to CH4, CO2 molecules have a much higher capacity to be adsorbed onto calcite pore surfaces. The diffusion capacity of CO2 molecules is much less in comparison with that of CH4 molecules, which could be attributed to diverse interactions between CO2 gas molecules and calcite nanopore surfaces. An effective displacement process of residual adsorbed CH4 in calcite slit nanopores by CO2 was performed, and it was found that the displacement efficiency was enhanced with an increase in the bulk pressure. This work provides microscopic information about the adsorption and diffusion properties of CH4 and CO2 in calcite nanopores, and confirmed the feasibility of the displacement of adsorbed CH4 in calcite nanopores by CO2, with the purpose of providing useful guidance for enhancing the extraction of shale gas by injecting CO2.

In this paper, the detailed behaviors of all the molecules, especially the interfacial array behaviors of surfactants and diffusion behaviors of gas molecules, in foam systems with different gases (N2, O2, and CO2) being used as foaming agents were investigated by combining molecular dynamics simulation and experimental approaches for the purpose of interpreting how the molecular behaviors effect the properties of the foam and find out the key factors which fundamentally determine the foam stability. Sodium dodecyl sulfate SDS was used as the foam stabilizer. The foam decay and the drainage process were determined by Foamscan. A texture analyzer (TA) was utilized to measure the stiffness and viscoelasticity of the foam films. The experimental results agreed very well with the simulation results by which how the different gas components affect the interfacial behaviors of surfactant molecules and thereby bring influence on foam properties was described.

In this study, the magnetic cellulose nanomaterials, containing magnetic nanoscale zerovalent iron (nZVI) and cellulose, were prepared by a novel reduction method and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The XRD and XPS results demonstrated the formation of zerovalent iron nanoparticles in the nanocomposite materials. With a saturation magnetization of 57.2 emu g−1, the cellulose@nZVI composites could be easily separated from solutions in 30 s through the external magnetic field. We investigated the adsorption performance of the magnetic cellulose nanomaterials for As(III) removal from aqueous solutions. The experimental results showed that arsenite adsorption followed the pseudo-second-order kinetic model and Langmuir isotherm model. A maximum removal of 99.27 % was observed for an initial concentration 10 mg L−1, at pH 8.0, and an adsorbent dose of 1.0 g L−1. Considering the high adsorption capacity, fast adsorption rate, and quick magnetic separation from treated water, the cellulose@nZVI composites were expected to be an efficient magnetic adsorbent for arsenic removal from aqueous solutions.