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Hyperbranched polymers (HBPs) have the characteristics of low viscosity, high fluidity, and excellent solubility, which enable them to have many potential applications in various fields. In this study, unequal activity 3,4′,5-trifluoro dibenzophenone (B'B 2) monomers and large volume 9,9-bis (4-hydroxyphenyl) fluorene (A 2) monomers were used to prepare hyperbranched poly (aryl ether ketones) (HBPAEKs) through nucleophilic substitution reaction, and three different hyperbranched HBPAEKs with hydroxy-terminated, fluoro-terminated, and epoxy-terminated groups were synthesized. The properties of the three HBPAEKs were systematically characterized by FT-IR, NMR, GPC, TGA, DSC and others. The solubility test shows that the synthesized HBPAEKs were soluble in most common organic solvents. Thermal analysis results showed that the fluorine-terminated HBPAEKs had excellent thermal stability, with a 5% weight loss temperature of 568 °C (T d5% = 568 °C), which is equivalent to that of poly (ether ether ketone) (PEEK, T d5% = 573 °C). Moreover, by adding HBPAEKs, the Melt Flow Rates (MFR) of PEEK was increased by 59%, which can greatly improve the processability of PEEK. [Display omitted] • Three different terminated HBPAEKs were successfully synthesized with high branching degrees and excellent solubility. • The fluorine-terminated HBPAEKs showing excellent thermal stability, which is comparable to that of PEEK (T d5% =573 ℃). • The HBPAEKs significantly enhanced the MFR of PEEK, which effectively mitigated the poor processability of PEEK. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have attracted widespread attention as future energy storage systems. However, the development of advanced anodes for SIBs still lags far behind. Metal sulfides exhibit high theoretical capacity yet suffer from low rate-capability and limited life span, resulted from their poor electric conductivity, volumetric fluctuation, and polysulfide dissolution and shuttling. Herein, a two-dimensional (2D) vertical aligned nickel sulfide nanosheets grown uniformly on reduced graphene oxide (rGO) is designed. The unique 2D on 2D structure enhances the electrolyte/electrode contact and reduces the migration/diffusion path of electrons/Na+, thereby greatly improving the rate-performance. Besides, the rGO provides sufficient surface area to absorb polysulfides, which effectively mitigates the shuttling of the intermediates. The NiS@rGO composite delivers 360 mAh/g after 800 cycles at 5 A/g, and a capacity of 540 mAh/g is maintained after 100 cycles at 0.1 A/g. In-situ XRD diffraction confirmed the reversible transformation between NiS and Ni during cycling. Furthermore, when coupled with the well-developed Na 3 V 2 (PO 4) 3 @C (NVP@C) cathode, the NiS@rGO/NVP@C full cell achieves a stable discharge capacity of around 200 mAh/g. [Display omitted] [ABSTRACT FROM AUTHOR]

Acrylic fiber is one of three important synthetic fibers in the world. The disposal and reuse of large number of waste acrylic fibers from fabric manufacturers or waste recovery is an urgent economic and environmental issue. Here, a porous carbon was derived from waste acrylic fibers via pre-oxidized, carbonization and KOH activation. Furthermore, we adopted melamine as nitrogen source to dope the porous carbon materials. When used as the anode of lithium ion batteries, this nitrogen-doped porous carbon shows high reversible capacity of ca. 1200 mA h g −1 after 50 cycles at 0.1 A g −1 . Reversible capacities of 550 and 370 mA h g −1 are obtained at higher current densities of 1 and 5 A g −1 after 500 cycles, respectively. The outstanding electrochemical performance are a result of its large mesopore volume, high-level N-doping (especially, pyridinic-N), large quantity of edge defects, and three-dimensional hierarchical porous architecture. This paper demonstrates that the reuse of waste industrial acrylic fibers as energy storage materials is a promising method for both energy and environmental fields. [ABSTRACT FROM AUTHOR]

The rational structure design and strong interfacial bonding are crucially desired for high performance zinc oxide (ZnO)/carbon composite electrodes. In this context, micro-nano secondary structure design and strong dopamine coating strategies are adopted for the fabrication of flower-like ZnO/carbon (ZnO@C nanoflowers) composite electrodes. The results show the ZnO@C nanoflowers (2–6 μm) are assembled by hierarchical ZnO nanosheets (∼27 nm) and continuous carbon framework. The micro-nano secondary architecture can facilitate the penetration of electrolyte, shorten lithium ions diffusion length, and hinder the aggregation of the nanosheets. Moreover, the strong chemical interaction between ZnO and coating carbon layer via C-Zn bond improves structure stability as well as the electronic conductivity. As a synergistic result, when evaluated as lithium ion batteries (LIBs) anode, the ZnO@C nanoflower electrodes show high reversible capacity of ca. 1200 mA h g −1 at 0.1 A g −1 after 80 cycles. As well as good long-cycling stability (638 and 420 mA h g −1 at 1 and 5 A g −1 after 500 cycles, respectively) and excellent rate capability. Therefore, this rational design of ZnO@C nanoflowers electrode is a promising anode for high-performance LIBs. [ABSTRACT FROM AUTHOR]

The current routes to couple dispersive liquid-liquid microextraction with capillary electrophoresis are the evaporation of water immiscible extractants and the back-extraction of analytes. In this study, a new methodology for this combination using water-in-oil microemulsion electrokinetic chromatography coupled with normal stacking mode on-line sample concentration was developed to analyze chlorophenols in water samples. The analytes were extracted with tributyl phosphate and the extractant dilution (3×) was directly injected into an electrophoresis buffer (7.7 cm) containing 5% sodium dodecyl sulfate, 78% 1-butanol, 2% 1-heptane, and 15% sodium acetate solution (pH 8.0). This proposed method is very simple and convenient compared to the conventional procedures. The key parameters affecting separation and concentration were systematically optimized. Under the optimized conditions, dispersive liquid-liquid microextraction contributed an enrichment factor of 45-50, and the overall sensitivity improvement was 312-418-fold. Limits of detection between 1.4 and 3.0 ng/mL and limits of quantification between 4.5 and 10.2 ng/mL were achieved. Acceptable repeatability lower than 3.0% for migration time and 9.0% for peak areas were obtained. The developed method was successfully applied for analysis of the chlorophenols in real water samples. [ABSTRACT FROM AUTHOR]

With the rapid development of high-frequency communication and large-scale integrated circuits, insulating dielectric materials require a low dielectric constant and dielectric loss. Poly (aryl ether ketone) resins (PAEK) have garnered considerable attention as an intriguing class of engineering thermoplastics possessing excellent chemical and thermal properties. However, the high permittivity of PAEK becomes an obstacle to its application in the field of high-frequency communication and large-scale integrated circuits. Therefore, reducing the dielectric constant and dielectric loss of PAEK while maintaining its excellent performance is critical to expanding the PAEK applications mentioned above. This study synthesized a series of poly (aryl ether ketone) resins that are low dielectric, highly thermally resistant, and soluble, containing cyclohexyl and diphenyl fluorene. The effects of cyclohexyl contents on the properties of a PAEK resin were studied systematically. The results showed that weakly-polarized cyclohexyl could reduce the molecular polarization of PAEK, resulting in low permittivity and high transmittance. The permittivity of PAEK is 2.95–3.26@10GHz, and the transmittance is 65–85%. In addition, the resin has excellent solubility and can be dissolved in NMP, DMF, DMAc, and other solvents at room temperature. Furthermore, cyclohexyl provided PAEK with excellent thermal properties, including a glass transition temperature of 239–245 °C and a 5% thermogravimetric temperature, under a nitrogen atmosphere of 469–534 °C. This makes it a promising candidate for use in high-frequency communications and large-scale integrated circuits. [ABSTRACT FROM AUTHOR]

The development of green, controllable, and simplified pathways for rapid dopamine polymerization holds significant importance in the field of polydopamine (PDA) surface chemistry. In this study, a green strategy is successfully devised to accelerate and control the polymerization of dopamine through the introduction of ozone (O3). The findings reveal that ozone serves as an eco‐friendly trigger, significantly accelerating the dopamine polymerization process across a broad pH range, spanning from 4.0 to 10.0. Notably, the deposition rate of PDA coatings on a silicon wafer reaches an impressive value of ≈64.8 nm h−1 (pH 8.5), which is 30 times higher than that of traditional air‐assisted PDA and comparable to the fastest reported method. Furthermore, ozone exhibits the ability to accelerate dopamine polymerization even under low temperatures. It also enables control over the inhibition–initiation of the polymerization process by regulating the "ON/OFF" mode of the ozone gas. Moreover, the ozone‐induced PDA coatings demonstrate exceptional characteristics, including high homogeneity, good hydrophilicity, and remarkable chemical and mechanical stability. Additionally, the ozone‐induced PDA coatings can be rapidly and effectively deposited onto a wide range of substrates, particularly those that are adhesion‐resistant, such as polytetrafluoroethylene (PTFE). [ABSTRACT FROM AUTHOR]

Highlights • Large specific surface area porous carbon. • Biomass-derived nitrogen/oxygen co-doped biomass carbon. • Excellent rate capability and cycle stability performance in sodium ion battery. Abstract Biomass derived porous carbons are economic and attractive materials for anode electrodes in sodium-ion batteries. In this work, a novel porous carbon has been prepared through activation of longan shell, which demonstrates an interconnected hierarchical porosity comprised of macro-, meso- and micro-pores as well with a high specific surface area of 2990 m2 g−1. Benefiting from the unique pore structure and oxygen and nitrogen dual doping, a well-developed ionic and electronic conductivity is achieved. Remarkably, it exhibits an excellent cycling stability with a capacity up to 345.9 mAh g−1 at a current density of 0.1 A g−1, and maintains a capacity of 304.2 mAh g−1 even at a high current density of 5 A g−1 after 1000 cycles as anodes for sodium-ion batteries. These results indicate that the fabricated porous carbon could be a promising electrode material for sodium-ion batteries. The mechanism of such high sodium-ion storage was also discussed with the scan-rate-dependent CV curves to quantify the pseudo-capacitive contribution. [ABSTRACT FROM AUTHOR]

Graphical abstract A simple co-precipitation approach to fabricate the Ni-NiCo 2 O 4 @ZnCo 2 O 4 yolk-shell nano-tetrahedron composites has been developed, which significantly improve the structural stability and conductivity of composite materials and exhibit excellent cycling and rate performance for lithium ion batteries. Highlights • A Ni-NiCo 2 O 4 @ZnCo 2 O 4 yolk-shell nano-tetrahedron has been prepared. • The capacity is up to 1571.9 mA h g−1 at 0.1 A g−1. • Ni-NiCo 2 O 4 @ZnCo 2 O 4 exhibited excellent rate capability and cycle stability. • Its excellent electrochemical performance came from yolk-shell architecture and the Ni-doping. Abstract Transition-metal oxide materials have gained significant attention as high-performance anode materials for lithium ion batteries. Great advances have been achieved in the development of micro/nanostructured materials with controllable shape and tunable pore size. In this work, a facile co-precipitation approach has been developed to fabricate the Ni-NiCo 2 O 4 @ZnCo 2 O 4 yolk-shell nano-tetrahedron composites, which significantly improve the structural stability and conductivity of the material. The Ni-NiCo 2 O 4 @ZnCo 2 O 4 is proven to exhibit excellent cycling and rate performance for lithium ion batteries, such as the charge capacity of 1571.9 mA h g−1 after 70 cycles at 0.1 A g−1, 1097.5 mA h g−1 after 600 cycles at 1.0 A g−1. This superior electrochemical performance may attribute to the yolk-shell architecture and the Ni-doping. [ABSTRACT FROM AUTHOR]

For the analysis of edible oils, saponification is well known as a useful method for eliminating oil matrices. The conventional approach is conducted with alcoholic alkali; it consumes a large volume of organic solvents and impedes the retrieval of analytes by microextraction. In this study, a low-organic-solvent-consuming method has been developed for the analysis of benzo[a]pyrene in edible oils by high-performance liquid chromatography with fluorescence detection. Sample treatment involves aqueous alkaline saponification, assisted by a phase-transfer catalyst, and selective in situ extraction of the analyte with a supramolecular solvent. Comparison of the chromatograms of the oil extracts obtained by different microextraction methods showed that the supramolecular solvent has a better clean-up effect for the unsaponifiable matter from oil matrices. The method offered excellent linearity over a range of 0.03- 5.0 ng mL−1 ( r > 0.999). Recovery rates varied from 94 to 102% (RSDs <5.0%). The detection limit and quantification limit were 0.06 and 0.19 μg kg−1, respectively. The proposed method was applied for the analysis of 52 edible oils collected online in China; the analyte contents of 23 tested oil samples exceeded the maximum limit of 2 μg kg−1 for benzo[a]pyrene set by the Commission Regulation of the European Union. [ABSTRACT FROM AUTHOR]

Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260–791. Limits of qualification ranged from 5.5 to 16.0 ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl − ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyl-capped HBP resins containing 2,4,6-tris(p-phenyl)pyridine were synthesized. • The synthesis conditions of the HBP were optimized by orthogonal tests. • The effect of the addition of HBP on the properties of epoxy resins was investigated. • In addition to good properties [T g : 113.9 °C, impact strength: 57.03 kJ/m2]. Epoxy resins are well used in many fields, but their problem of poor toughness restricts the further expansion of their applications. Facing this problem, this study successfully prepared high toughness epoxy resins using hydroxyl-terminated hyperbranched poly(aryl ether ketone) (HBPAEK-OH) as a toughening agent. Firstly, HBPAEK-OH was synthesized based on molecular structure design, combined with the optimized conditions of heat resistance and solubility. Then HBPAEK-OH was mixed with bisphenol A diglycidyl ether (DGEBA) to prepare a series of epoxy resins (HBP/DGEBA-n) with superior thermal properties, whose glass transition temperature (T g) can reach 113.9 °C, which is about 38 °C higher than that of HBP/DGEBA-0. The tensile strength, flexural strength, impact strength, and elongation at break of HBP/DGEBA-n showed a tendency to increase and then decrease with the increase of HBPAEK-OH content, and the highest values reached 86.43 MPa, 128.50 MPa, 57.03 kJ/m2, and 7.15 %, respectively. Among them, the impact strength and elongation at break increased by 179.3 % and 87.2 %, indicating that the toughness of HBP/DGEBA-n was significantly improved. This study explores a new method for toughening epoxy resins, which improves their toughness and heat-resistant properties and provides new possibilities for their expansion in different applications. [ABSTRACT FROM AUTHOR]

Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodium-ion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the construction of heterogeneous interfaces of multimetal sulfides remain great challenges. Herein, a hierarchical 1T-MoS 2 /carbon nanosheet decorated Co 1– x S/N-doped carbon (Co 1– x S/NC@MoS 2 /C) hollow nanofiber was designed and constructed via a one-pot hydrothermal method using a cobalt-based coordination polymer nanofiber. This nanofiber can transform in-situ into conductive N-doped carbon hollow fibers embedded with active Co 1– x S nanoparticles, enabling the epitaxial growth of MoS 2 nanosheets. Consequently, the Co 1– x S/NC@MoS 2 /C composites achieve exceptional lithium/sodium-ion storage performance. Compared to MoS 2 /C microspheres and Co 1– x S/NC hollow nanofibers alone, the Co 1– x S/NC@MoS 2 /C hollow nanofibers deliver higher discharge capacities (1085.9 mAh g−1 for lithium-ion batteries (LIBs) and 748.5 mAh g−1 for sodium-ion batteries (SIBs) at 100 mA g−1), better capacity retention (910 mAh g−1 for LIBs and 636.5 mAh g−1 for SIBs after 150 cycles at 100 mA g−1), and increased cycling stability (407.2 mAh g−1 after 1000 cycles for SIBs at 1000 mA g−1). Furthermore, the kinetic analysis shows that the lithium/sodium-ion storage processes of the Co 1– x S/NC@MoS 2 /C electrode are mainly controlled by pseudocapacitance behavior. The excellent electrochemical properties can thus be ascribed to the synergy of the MoS 2 /C nanosheets with the enlarged interlayer spacing, good conductivity of the carbon layers, and the Co 1– x S nanoparticles embedded in the hollow nanofibers with extensive reaction sites. [ABSTRACT FROM AUTHOR]

Graphical abstract A simple electrospinning approach has been developed to fabricate the Mo 2 C@C core-shell nanofibers, which significantly improves the structural stability and conductivity, exhibit excellent cycling and rate performance as anode of lithium-ion batteries. Highlights • Hollow Mo 2 C@C core-shell nanofibers have been synthesized via an coaxial electrospinning. • The hollow Mo 2 C@C composites can enhance the performance during the alloying reactions. • The obtained nonofibers exhibit excellent rate capability and cycle stability. Abstract Hollow Mo 2 C@C core-shell nanofibers (H-Mo 2 C@C/NFs) have been successfully synthesized via an integrated procedure including coaxial electrospinning, oil extraction and carbonization. As an anode of lithium-ion batteries, H-Mo 2 C@C/NFs delivers high discharge capacity of 1176.3 mA h g−1 in the first cycle at a current density of 0.1 A g−1 and exhibits good rate capability and reversibility. The capacity can maintain at 595.1 mA h g−1 even when the current density is up to 5 A g−1. In addition, at a high current density of 1 A g−1, H-Mo 2 C@C/NFs also displays extraordinary long-term cycling performance with a capacity of 674.4 mA h g−1. The excellent rate performance and cycling stability result from the synergistic effect of Mo 2 C nanoparticles and hollow structure nanofiber matrix. Coaxial electrospinning technology can be widely extended to manufacture other metal carbide/carbon composites to achieve important energy storage and other applications. [ABSTRACT FROM AUTHOR]

Abstract Exploiting new comonomers is still required for high performance polyacrylonitrile (PAN) based carbon fiber. In this paper, we have proposed an efficient methodology, combining of theoretical calculation and experimental verification, to develop new comonomer for polyacrylonitrile (PAN)-based carbon fiber. The cyclization energy barriers of PAN copolymers, including comonomers of α-nitryl acrylic acid (IA-NO 2), α-amino acrylic acid (IA-NH 2), acrylamide (AAM), itaconic acid (IA), and ethylenesulfonic acid (ESA), have been calculated based on the autocatalytic cyclization mechanism using density functional theory (DFT) at B3LYP/6-31 + G (d, p) level. The theoretical calculation indicated that ionic cyclization of nitrile group was more easily initiated by ESA than other comonomers. Correspondingly, the PAN copolymers including comonomers of ESA and IA have been prepared and studied on their properties. The experimental results further demonstrated the P(AN-co-ESA) copolymer had better thermal properties such as smaller cyclization energy, slower heat release rate, and higher char yielding. Therefore, this theoretical calculation combined with experimental verification methodology is a powerful tool for exploiting new comonomer for PAN-based carbon fiber. Graphical abstract Image 1 Highlights • The cyclization energy barriers of selective comonomers were calculated via DFT. • The nitrile group is more easily initiated by ESA than the others by calculation. • The new comonomer of ESA containing sulfonic group has better thermal properties. • Combined theory and experiment are a useful methodology to exploit new comonomers. [ABSTRACT FROM AUTHOR]

• A 2D MXene wrapped Ni-Fe oxide nanocube based flexible electrode was synthesized. • The composite film functioned like a mixed analogous heterostructure. • The film successfully combined the advantages of different components. • The film demonstrated satisfied electrochemical performance and flexibility. In this work, we addresses the fabrication of a flexible film electrode based on 2D MXene wrapped 3D Ni-Fe oxide nanocube mixed analogous heterostructure. The resulted composite film electrode successfully inherits the merit of different building blocks: MXene layers works as binders and conductive additives that can connect cubic Ni-Fe oxide nanoparticals, facilitate the charge transfer and avoid a significant conductivity decrease in the resulting electrode. While cubic Ni-Fe oxide serves as an active spacer inside the adjacent MXene layers to increase the interlayer space, facilitate the electrolyte diffusion and enhance the electrochemical activity of the composite film. As a result, the optimized composite film manifests excellent specific capacitance of 1038.43 mF cm−2 at current density 0.5 mA cm−2. Meanwhile by assembling into all-solid-state flexible supercapacitor, an excellent specific areal capacitance of 328.35 mF cm−2 at 0.2 mA cm−2 was achieved. Additionally, the excellent energy storage performance is well maintained with a capacitance retention of 90.9% during 10,000 charging-discharging long cycles. Furthermore, a high mechanical robustness with 88.9% capacitance remained after subjected to bending at 90° for 50 cycles, suggesting great potentials for the applications in future flexible and wearable devices. [ABSTRACT FROM AUTHOR]