In contrast to the borrowing hydrogentype N-alkylation reactions, in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the addition of external aldehydes was accidentally found to be a simple and effective protocol for alcohol activation. This interesting finding subsequently led to an efficient and green, practical and scalable aldehyde-catalyzed transition metal-free dehydrative N-alkylation method for a variety of amides, amines, and alcohols. Mechanistic studies revealed that this reaction most possibly proceeds via a simple but interesting transition metal-free relay race mechanism.
An air-stable oxidation state is observed in an electrochromic triphenylamine–triazine polymer energy storage system after the removal of the applied potential.
Addressing the conflict between achieving high mechanical properties and room-temperature self-healing ability is extremely significant to achieving a breakthrough in the application of self-healing materials. Therefore, inspired by natural spider silk and nacre, a room-temperature self-healing supramolecular material with ultrahigh strength and toughness is developed by synergistically incorporating flexible disulfide bonds and dynamic sextuple hydrogen bonds (H-bonds) into polyurethanes (PUs). Simultaneously, abundant H-bonds are introduced at the interface between graphene oxide nanosheets with dynamic multiple H-bonds and the PU matrix to afford strong interfacial interactions. The resulting urea-containing PU material with an inverse artificial nacre structure has a record mechanical strength (78.3 MPa) and toughness (505.7 MJ m −3 ), superior tensile properties (1273.2% elongation at break), and rapid room-temperature self-healing abilities (88.6% at 25 °C for 24 h), forming the strongest room-temperature self-healing elastomer reported to date and thus upending the previous understanding of traditional self-healing materials. In addition, this bionic PU−graphene oxide network endows the fabricated flexible intelligent robot with functional repair and shape memory capabilities, thus providing prospects for the fabrication of flexible functional devices.
Although organometal halide perovskite materials have shown great potential in light-emitting diodes, their performance is greatly restricted by the poor morphology of the perovskite layer. In this work, we demonstrate a facile one-step solution method to improve the perovskite film morphology via a non-solvent/solvent mixture. An efficient CH3NH3PbBr3-based light-emitting diode was prepared with a chlorobenzene/N,N-dimethylformamide mixed solvent. A high efficiency of 0.54 cd A(-1) is demonstrated, which is 22 times higher than that of a device fabricated by a traditional one-step solution process. Furthermore, the uniformity of the emission region and the device stability are strongly improved by this facile one-step solution process. Our work paves a new way for the morphological control of perovskite films for application in light-emitting diodes.
In this paper, we consider two-dimensional Riesz space fractional diffusion equations with nonlinear source term on convex domains. Applying Galerkin finite element method in space and backward difference method in time, we present a fully discrete scheme to solve Riesz space fractional diffusion equations. Our breakthrough is developing an algorithm to form stiffness matrix on unstructured triangular meshes, which can help us to deal with space fractional terms on any convex domain. The stability and convergence of the scheme are also discussed. Numerical examples are given to verify accuracy and stability of our scheme.
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