Significantly improved interfacial properties of silicon dioxide nanowire functionalized poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers/polytetrafluoroethylene (PTFE) wave-transparent laminated composites

Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber and polytetrafluoroethylene (PTFE) resin have been widely acknowledged as excellent wave-transparent materials for future high-frequency applications due to their exceptional dielectric properties. However, the weak interfacial bonding between these two materials hampers their full potential. In this study, we successfully addressed this limitation by enhancing the surface roughness of PBO fibers and introducing active sites through the in-situ grafting of silica nanowires. The added silica acted as an interfacial anchor on the PBO fiber surface, significantly improving the bonding force between PBO and PTFE. PBO/PTFE wave-transparent laminated composites were fabricated using hot compression molding. The results demonstrate that the PBO (treated with in-situ grown silica)/PTFE laminated composites exhibit superior interlaminar shear strength (ILSS), flexural strength, flexural modulus, and tensile modulus compared to the pristine PBO/PTFE laminated composites. Specifically, these properties are found to be 58.6%, 32.9%, 138.1%, and 25.35% higher, respectively. Additionally, these composites demonstrate low dielectric constant and dielectric loss. Most notably, they achieve a wave transmittance of 91.45% at 10 GHz, indicating significant potential for wide-range applications in next-generation advanced military weapons, such as “lightweight/high-strength/wave-transparent” electromagnetic window materials, as well as civilian communication base stations.