Fe ions doped SnO2/MWCNTs composites with 48.8% Fe ions doping content showed the maximum reflection loss was −44.54 dB at 15.44 GHz, and the maximum absorption bandwidth of reflection loss below −10 dB was 4.5 GHz in the Ku band.

Ni-doped SnO2@MWCNTs composites were synthesized by a facile one-step hydrothermal method, and had a maximum reflection loss of −39.2 dB at 8.2 GHz and the absorption bandwidth of reflection loss lower than −10 dB was 3.6 GHz.

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Flame retardants endow epoxy resins (EP) with flame retardance, however, their introduction often lead to the decrease in the glass transition temperature (Tg), which is an important property for EP. Therefore, it is significant to design and synthesize a high‐efficiency flame retardant that enhances flame retardance and Tg of EP. To achieve this goal, a hyperbranched polyamide oligomer containing DOPO (HPD) was successfully synthesized by A4 + B2 polymerization and its structure was confirmed by FTIR, 1H NMR, and 30P NMR spectra and GPC. HPD was used as an additive flame retardant in epoxy resin, and its effect on the flame retardance and thermal properties of epoxy resin was studied. The epoxy resin with 7.5 wt% HPD reached UL‐94V‐0 rating and a higher LOI value of 29.6%, and its Tg was 176.2°C, which is higher than the pure epoxy resin. Moreover, the results of cone calorimetry testing (CCT) and TG‐FTIR analysis suggested that the gas‐phase and condensed‐phase flame‐retarded roles of HPD delayed the time to ignition, and reduced the value of relevant combustion parameters, including the peak of heat release rate, average of heat release rate, total heat release, smoke production rate, and total smoke production. The analysis results of Py‐GC/MS test of HPD further confirmed that HPD was able to play the flame‐retarded role in the gaseous and condensed phases.

In this study, Zn-doped Fe3O4 nanoparticles were successfully synthesized by a facile solvothermal method in the presence of sodium dodecyl sulfate (SDS). The morphology, magnetic properties and electromagnetic wave absorbing properties of these materials were characterized. Results showed that Zn[Formula: see text] played a significant role in the formation of Zn-doped Fe3O4. With the protection of SDS, highly dispersed Fe3O4 nanoparticles were obtained. The nanoparticle size decreased after Zn[Formula: see text] doping, and the dispersity deteriorated with increasing Zn[Formula: see text] doping concentration. Zn-doped Fe3O4 exhibited excellent electromagnetic wave absorbing property, which resulted in magnetic loss and dielectric loss at an appropriate doping concentration. The minimum reflection loss (RL) was approximately [Formula: see text][Formula: see text]dB at 16.9[Formula: see text]GHz. As the coating layer thickness increased to 4.0[Formula: see text]mm, the bandwidth was approximately 5.0[Formula: see text]GHz corresponding to RL below [Formula: see text][Formula: see text]dB, which nearly covered the entire S band (2–4[Formula: see text]GHz) and C band (4–8[Formula: see text]GHz). The peak frequency of RL and the number of peaks matched the quarter-wave thickness criteria. It was believed that the Zn-doped Fe3O4 could be a potential electromagnetic wave absorbing material in S and C bands.

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In order to give epoxy resin good flame retardance, a novel bio-based flame retardant based on 2-aminopyrimidine (referred to as VAD) was synthesized from renewable vanillin as one of the starting materials. Its structure was confirmed by NMR and mass spectra. The epoxy resins containing VAD were prepared by utilizing 4,4-diaminodiphenylmethane (DDM) as a co-curing agent, and their flame-retardant, mechanical and thermal properties and corresponding mechanisms were studied.VAD accelerated the cross-linking reaction of DDM and E51 (diglycidyl ether of