Mechanically strong PBO wave-transparent composite papers with excellent UV resistance and ultra-low dielectric constant

Poly(p-phenylenebenzobisoxazole) nanofibers (PNF), as a novel kind of nanofibers, have attracted significant attention from researchers. However, their poor ultraviolet (UV) resistance limits their potential applications. In this work, zinc oxide (ZnO) was uniformly coated on the surface of PNF-containing polysilsesquioxane (POSS) via in-situ growth to obtain (POSS-PNF)@ZnO. Subsequently, (POSS-PNF)@ZnO wave-transparent composite paper was then fabricated using a “vacuum filtration-assisted hot-pressing” method. Based on the coordination interaction between O–C=O groups of PNFs and ZnO, as well as the UV absorption/shielding capability of ZnO, the (POSS-PNF)@ZnO wave-transparent composite paper exhibited superior mechanical properties and UV resistance. At a hydrothermal reaction temperature of 80°C, the prepared (POSS-PNF)@ZnO wave-transparent composite paper exhibited the highest tensile strength (204.5 MPa) and toughness (12.3 MJ m³), which represents increases of 23.7% and 32.3%, respectively, compared to POSS-PNF wave-transparent paper. After 288 h of UV aging, the tensile strength retention rate was 77.4%, significantly higher than the 53.7% of POSS-PNF wave-transparent composite paper. Moreover, it exhibited excellent wave-transparent performance with a dielectric constant (ε) of 2.15 and a dielectric loss tangent (tanδ) of 0.044 at 10 GHz, resulting in a wave-transparent coefficient of 95.9%.