The demand for higher integration and operational stability in modern electronics has increased the need for polymers with excellent dielectric and mechanical properties. While incorporating nanofillers can enhance dielectric performance, high loadings often worsen mechanical properties and dielectric loss. Achieving low dielectric loss and high mechanical robustness under ultralow nanofiller loadings remains a critical yet unsolved challenge. Here, we present polypropylene (PP) nanocomposites with only 0.5 wt.% nanofillers, fabricated via a combination of stretching orientation and annealing strategies. The coupled orientation of molecular chains and nanofillers under stretching generates a spatially ordered dielectric framework that increases crystallinity by ~ 10% and mitigates electric field concentration. Subsequent annealing stabilizes this oriented structure through constrained chain relaxation and crystalline perfection, reducing losses during dipole steering. The optimal nanocomposites exhibit remarkable breakdown strength (528 MV/m) and tensile strength (215 MPa), while maintaining ultralow dielectric loss (5.5 × 10⁻⁴), outperforming most PP-based composites. Finite element simulations indicate that the homogeneous and directional arrangement of nanofillers effectively hinders electrical damage propagation. Additionally, the oriented nanocomposites demonstrate exceptional impedance matching, which is beneficial for signal transmission. This strategy addresses the trade-off between enhanced insulation and low filler loading, enabling polymer nanocomposites with efficient signal transmission and reliable processability.

Higher electromagnetic wave absorption (EMWA) performance, more flexible and lower density are the incompatibility for the flexible EMWA materials, the insufficient analysis of attenuation conditions for every part in the bulk EMWA materials based on electrical/magnetic properties and reflection loss (RL) resulted in the inability to obtain the actual electromagnetic wave (EMW) consumption capacity in EMWA materials during practical applications. In this study, the lightweight flexible EMWA composites fabricated by Co-based aerogels have broadest effective absorption band (EAB, frequency for reflection loss≤−10 dB) of 5.77 GHz, best minimum reflection loss (RL_min) of −49.94 dB and maximum radar cross section (RCS) reduction of 29.55 dB·m². After the salt spray test for the flexible EMWA composites, the largest EAB, optimum RL_min and greatest RCS reduction are 5.42 GHz, −24.41 dB and 19.34 dB·m². The power loss density (PLD) distribution of EMW in all regions of the bulk EMWA materials is calculated based on electromagnetic parameters, and the influence of RL and the magnetic variation on PLD distribution is investigated. The flexible EMWA composite with 18% (in mass) Co-800 aerogel is a very promising lightweight EMWA material for preventing electromagnetic interference/pollution and enhancing radar stealth in the salt-spray environment.

With the development of electronic information science and technology, electromagnetic information security and electromagnetic pollution become more and more serious. Electromagnetic wave absorption (EMWA) rubber based on the absorbent of carbon with low density and good corrosion resistance is a kind of good EMWA materials for solving electromagnetic information security and electromagnetic pollution. In this article, three-dimensional network structure carbon nanofiber aerogels (3DNSCAs) are prepared by vacuum annealing of three-dimensional network structure agarose/zinc acetate obtained by freeze-drying of agarose/zinc acetate gel. The EMWA rubber composites with 2.2% (in mass) 3DNSCAs have almost the same density as silicone rubber (PDMS), and the dispersity of 3DNSCAs in PDMS is studied by rheological analysis. The effective absorption bandwidth (EAB, frequency for reflection loss <–10 dB) of the 2 mm thick PDMS/C-800 is 4 GHz, and the minimum value of reflection loss (RL_min) is −52 dB with the thickness of 3.5 mm. The PDMS/C-1000 with the thickness of 3.5 mm has an EAB up to 4.8 GHz. Radar cross section (RCS) reduction of PDMS/C-800 can achieve 20 dB·m² at the frequency of 6 GHz.