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Due to the shortage of petroleum resources, poly(lactic acid) (PLA), a biodegradable polymer, has been widely considered as a replacement for traditional petroleum-based polymers. Therefore, multifunctional PLA composites have become increasingly popular. In this study, conductive carbon nanotubes (CNTs) and magnetic nano-Fe3O4 fillers were melt-blended with PLA. The impact of CNTs and nano-Fe3O4 composition on the electrical and electromagnetic interference (EMI) shielding properties of PLA nanocomposites was investigated in detail by adjusting the CNTs-to-nano-Fe3O4 ratio. When the hybrid filler content was fixed at 10 wt%, the electrical conductivity results indicated that the addition of single CNTs could effectively improve the conductivity of the nanocomposites, while nano-Fe3O4 contribution was hardly noted. A suitable ratio of electromagnetic hybrid fillers can yield excellent synergistic effects in EMI shielding properties. The nanocomposites containing CNTs and nano-Fe3O4 in a 50:50 ratio exhibited excellent electrical conductivity (90.6 S·m−1) and EMI shielding effectiveness (EMI SE ∼ 40.5 dB). This is primarily because CNTs provide good electrical conductivity, but the addition of magnetic nano-Fe3O4 provides additional interfacial polarization and eddy current losses caused by its dielectric and magnetic properties. These properties synergistically result in an impedance mismatch, dielectric loss, and polarization relaxation of the composite materials, improving the shielding properties against electromagnetic waves. Further, it was found that changing the ratio of electromagnetic hybrid fillers also affected electromagnetic wave absorption. When the ratio of CNT-to-nano-Fe3O4 was 25:75, the nanocomposites had an EMI SE of 24.6 dB, and the absorptivity could reach the maximum (40.3%). Thus, this study provides a valuable reference for preparing multifunctional polymer nanocomposites by constructing electromagnetic hybrid filler networks.

Polyimide (PI) is widely used in the field of microelectronics because of its excellent thermal, mechanical, optical, and electrical properties. With the development of electronics and information industry, PI as a dielectric material needs to possess low dielectric loss. PI/carbon quantum dots (PI/CQDs) composite films with low dielectric loss were prepared by introducing CQDs into PI matrix. At 25°C and 1 kHz voltage, the dielectric loss of pure PI film is about 0.0057. The dielectric loss of PI/CQDs composite film is about 0.0018, which is about 68% lower than that of pure PI film. The dielectric loss of PI/CQD composite film is greatly reduced while the mechanical properties and thermal properties of PI/CQDs composite film roughly remain unchanged. Due to the cross-linking structure formed between CQDs and PI molecular chain, the relative movement of PI molecular chain is hindered.

In light of the small ring strain of five/six-membered cyclic ethers, constructing complex molecules via ring-opening reactions has consistently been a highly challenging topic in organic synthesis. Induced by Lewis acids, the charge redistribution in cyclic ethers forms oxonium ylide intermediates, thereby activating the C–O bond and subsequently facilitating nucleophilic attack for ring opening. In recent years, a variety of novel Lewis acids, encompassing those with new metal centers and frustrated Lewis pairs (FLPs), have been effectively utilized to induce the formation of oxonium ylides, offering a diverse array of methods for the ring opening of five/six-membered cyclic ethers. This review conveys the extensive application advancements of diverse Lewis acid types for cyclic ether ring-opening reactions over the past two decades, originating from the perspective of the classification of Lewis acids. Furthermore, the substrate applicability and chemical transformation efficiency of these Lewis acids in the ring-opening reactions of cyclic ethers have also been discussed herein. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe containing an imine structure was synthesized through a condensation reaction based on the skeleton of antipyrine. Due to the synergistic effect of photoinduced electron transfer (PET), excited-state intramolecular proton transfer (ESIPT), and E/Z isomerization, the probe itself has weak fluorescence. When zinc ions are added to the ethanol solution of the probe, the formed complex inhibits PET, ESIPT, and E/Z isomerization while activating chelation-enhanced fluorescence (CHEF), resulting in fluorescent "turn-on" at 462 nm. Under optimal detection conditions, the probe can rapidly respond to zinc ions within 3 min, with a linear range of 60–220 μM and a lower limit of detection (LOD) of 0.63 μM. It can also specifically identify zinc ions in the presence of 13 common metal ions. [ABSTRACT FROM AUTHOR]

All-organic high dielectric materials are highly required in the field of modern electronic industry and energy storage. In this work, all-organic polyimide/polysulfone composite films with different amounts of PSF (PI/PSF-X) were prepared by in situ polymerization followed by film casting and thermal treatment. The dielectric, mechanical and thermal properties of these PI/PSF-X composite films are characterized by dielectric measurement, tensile test, thermogravimetric analysis and dynamic mechanical analysis. The results suggest that the PI/PSF-X composite films have good dielectric properties, good mechanical properties and excellent thermal properties, which are suitable for applications in electronic devices in harsh environments, especially in high-temperature environments.