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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]

[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]

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]