Preparation and Wave‐Transparent Properties of Hollow Nano‐ <scp> SiO ₂ </scp> /Dicyclopentadiene Cyanate Ester‐Epoxidized Soybean Oil Composites

ABSTRACT With the rapid advancement of 5G/6G communication technologies, polymer‐based transparent wave composites urgently require synergistic optimization of low dielectric constant, ultra‐low dielectric loss, and high thermal stability. Although cyanate ester (CE) resins exhibit excellent high‐frequency dielectric properties, their inherent brittleness severely limits practical applications. This study employs bio‐based epoxidized soybean oil (ESO) to molecularly modify dicyclopentadiene‐based cyanate ester (DCPDCE) for comprehensive performance enhancement. Systematic investigations demonstrate that ESO introduction effectively regulates molecular polarization, significantly reducing both dielectric constant (ε) and loss (tanδ). To further improve dielectric performance, hollow nano‐SiO 2 with dielectric matching characteristics was incorporated as a reinforcing phase. At 7 wt% SiO 2 content, the DCPDCE‐ESO/SiO 2 composite achieved outstanding performance at 10 GHz: ε = 2.46, tan δ = 0.005, and transmittance increased to 0.971. This gradient dielectric structure offers a novel design concept for next‐generation high‐frequency transparent wave materials, highlighting bio‐based materials' application potential in high‐performance communication and providing an important technical pathway for environmentally friendly high‐frequency material development.