Yan Meng

In the Internet of things, a large number of sensors are needed, triboelectric nanogenerators(TENG)has been proved to be the best solution for energy supply. However, the traditional friction nano-generator has large voltage, small current, large internal resistance and small output power. Therefore, we report a gel-based Solid Ion Channel Battery (SICB) that can greatly improve the output performance compared to traditional triboelectric nanogenerators. Based on the traditional TENG, using PTFE(Polytetrafluoroethylene) and Cu as the friction layer, the ion gel was affixed to the back of copper, and different sodium chloride concentrations were experimentally tested. Finally, it was found that the SICB can achieve 260V open circuit voltage and 0.09mA short circuit current.

Non‐amine‐derived tetrafunctional epoxies have several advantages over the amine‐derived N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenyl methane (TGDDM) in high temperature applications. Although two non‐amine‐derived tetrafunctional epoxies were developed in our laboratory, further improvements in toughness using less loading amount is still desirable. Thus, a tertiary‐amine‐free, non‐planar and triphenylmethane‐containing tetrafunctional epoxy (STFE) with a sulfone spacer was synthesized. When it was mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4′‐diaminodiphenylsulfone (DDS), both thermal and mechanical performances outperformed TGDDM. Moreover, STFE modified system shows the highest toughness (35.7 kJ m^–2) among three amine‐free and triphenylmethane‐containing epoxies at merely 5 wt% loading. Molecular simulation and thermomechanical analysis results suggest that the improved mechanical properties could be related to the geometry of the molecule and larger free volume. Despite a marginal drop in T_g, the thermal degradation temperature is better than that of TGDDM/DDS. In addition, the moisture resistance of STFE/DGEBA/DDS is much better than that of TGDDM/DDS. Thus, STFE modified DGEBA could be a potential replacement for TGDDM in some high temperature applications. © 2020 Society of Chemical Industry

In this paper, hyperbranched polyether functionalized graphene oxide (EHBPE-GO) was prepared by a facile one-step method. Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analyzer (TGA), and trans-mission electron microscopy (TEM) results confirmed the formation of EHBPE-GO. Then, EHBPE-GO was cured with phenolic amides at room temperature to prepare epoxy coatings. The corrosion resistance of epoxy coatings was investigated systematically by using electrochemical and traditional immersion methods. Results show that a small amount of EHBPE-GO (8 wt % of Diglycidyl ether of bisphenol A (DGEBA)) in epoxy coating achieves 50% higher improvement in acid-resistance than unmodified neat DGEBA resin. For the nanocomposite epoxy coating, the superior acid-resistance is attributed to the increased crosslink density and the impermeable 2D structure of EHBPE-GO. This work provides a facile strategy to develop the effective improved corrosion resistance nanofiller for epoxy coating.

An intrinsic white-light-emitting semi-aliphatic hyperbranched polyimide with epoxide terminal groups (EHBPI) has been reported for the first time. The UV/vis absorption spectra and density functional theory calculations showed that the lowest electronic transition of the semi-aliphatic hyperbranched polyimide is hybridized local and charge transfer transition, whereas the lowest electronic transition of aromatic hyperbranched polyimides is charge transfer transition. Due to the hybridized local and charge transfer transition, semi-aliphatic EHBPIs emit visible fluorescence after excitation. The solution fluorescence results suggest that (1) fluorescence depends on the backbone structure and the terminal group; (2) solvent polarity, concentration, degree of aggregation, and temperature also affect emission behaviors; (3) both iron and copper ions quench the solution fluorescence, with Fe³⁺ being the most effective. The decreasing trend of the quantum yield with increasing concentration and/or addition of water as well as the higher solution-state quantum yield compared with that in the solid state indicate the ACQ nature of the fluorescence. Moreover, EHBPI3, which has the most flexible spacer, emits bluish green fluorescence in solution and emits white fluorescence in the solid state. The free-standing film prepared by blending EHBPI3 with poly(vinyl alcohol) also emits white fluorescence with a quantum yield of 0.05. The solid-state white fluorescence in a simple single-component hyperbranched polymer could offer unique benefits for certain applications.

Multilayer hyperbranched–hyperbranched polyethers with a tunable M _n and an invariant DB were reported for the first time.

A high performance, low cost, and environmentally friendly epoxy is demonstrated for the first time by copolymerizing a small amount of epoxide-terminated hyperbranched polyether (EHBPE) with DGEBA. Unlike typical epoxy systems, which involve large amounts of costly, toxic, and volatile curing agents, homopolymerized epoxy curing systems use only small amounts of catalysts instead of curing agents. However, high performance homopolymerized epoxy has not been reported so far, mainly due to brittleness and somewhat uncontrolled fast curing. Our results show that the addition of small amounts of epoxide-terminated hyperbranched polyether (EHBPE) into DGEBA can lead to simultaneous improvements in strength, toughness, and T_g. At 5 wt% EHBPE loading, the homopolymerized hybrid epoxy shows balanced mechanical performance and is suitable for structural materials. In the first part of the work, the effects of catalyst type and catalyst concentration were optimized using neat DGEBA. In the second part, DGEBA/EHBPE hybrid epoxy systems were cured and tested using those optimized conditions. Compared with neat DGEBA, the addition of 5 wt% EHBPE can increase toughness and tensile strength by 47.6% and 18.8%, respectively; in addition, T_g also increases from 171 to 173 °C.

The strong fluorescence, in both the solution and the bulk state, of a chromophore-free aliphatic hyperbranched polyether which does not contain N and P atoms was reported for the first time. Effects of concentration and solvent solubility were measured. Its ethanol solution shows a strong blue-green fluorescence (Y_u = 0.11–0.39), and its fluorescence shows a strong selective quenching with respect to Fe³⁺.