Hollow glass microsphere/polybutadiene composites with low dielectric constant and ultralow dielectric loss in high-frequency

High-frequency dielectric materials have been widely and rapidly applied in areas such as automotive radar, Internet of Things, artificial intelligence, and quantum computing. Currently, the challenge in high-frequency dielectric materials lies in reducing the dielectric constant (D_k) and dielectric loss (D_f) without sacrificing its mechanical properties. This study addresses this challenge by introducing air, as the most common “low dielectric factor,” into the polymer matrix in the form of hollow glass microspheres. Meanwhile, the reactive vinyl groups were also introduced onto the surface of the hollow glass microspheres, enabling an interfacial chemical reaction between the side vinyl groups of polybutadiene and its surface so that the organic–inorganic interface compatibility and interface peel strength are simultaneously improved. Consequently, the minimum D_k of 1.29 and D_f of 0.0012 in 3–18 GHz are achieved, and the interface peel strength also reaches 0.65 N/mm. Molecular dynamics simulations, analysis of dielectric properties, and interface peel strength reveal the influence of hollow glass microspheres' morphology and chemical structure on their high-frequency dielectric performance and adhesive strength. This paper provides effective strategies for the structural design and preparation of high-frequency, low-dielectric composites, contributing to the further development of next-generation microwave communication devices towards higher frequencies and faster information transmission.