Fabrication of low dielectric constant polyimide/TiO₂ nanofibers with enhanced UV-light shielding properties

Polyimide (PI)/titanium dioxide (TiO₂) composite nanofibers (NFs) with average diameters of 200–250 nm were synthesized via electrospinning. The total number density of dipoles decreased significantly, owing to the porous structures and compact interface between TiO₂ NPs and PI matrix. All PI/TiO₂ NFs maintain low dielectric constants and losses. For example, the dielectric constants of PI/TiO₂-6% NFs are all lower than 2.6, being exposed to temperatures from 25°C to 200°C. Meantime, the dielectric losses of PI/TiO₂-6% NFs are below 0.005. For ultraviolet (UV)-light shielding performance, the PI/TiO₂ NFs exhibited good UV-light shielding and corresponding anti-photoaging properties. The reason can be ascribed from high UV-light absorption and scattering ability in the TiO₂ NPs. The best UV-light absorption (average: 3.71) and corresponding absorption decay (15.13%) were achieved for optimized PI/TiO₂-6% NFs. Other fundamental characteristics, such as the thermal stability, mechanical tensile property, and hydrophobicity, were also investigated. Such low dielectric constant PI/TiO₂ composite NFs can be alternatively chosen under a longtime UV-light exposing condition.