Superhydrophobic Electrospun PI/PTFE Membranes with\nUltralow Dielectric Constants for High-Frequency Telecommunication

High-frequency, high-power, and high-speed telecommunication\nin\na complex environment promotes the development of dielectric materials\ntoward a low dielectric constant, low dielectric loss, good thermal\nproperties, and long-term reliability. Here, polyimide/polytetrafluoroethylene\n(PI/PTFE) nanofiber membranes with an inherent super hydrophobicity,\nexcellent dielectric properties, good thermal stability, and enhanced\ntensile strength were prepared via a simple electrospinning strategy\nand an imidization reaction. The obtained PI/PTFE membranes demonstrate\na superlow average dielectric constant of 1.22–1.27 and a dielectric\nloss of 0.032–0.048 in high frequency, together with an enhanced\ntensile strength, benefiting from the special nanofiber-bead structure\nformed in the composite membrane. The mixing of polyamic acid (PAA)\nand PTFE in the electrospinning solution endows the obtained PI/PTFE\nnanofiber membrane with a uniform distribution of PTFE and thus an\ninherent superhydrophobicity with a water contact angle of 156.1 and\n159.2° for PI/PTFE-30% and PI/PTFE-40%, respectively. Besides,\nthe hydrophobicity could be kept even after standing more than 10,000\nwater drops, and the thermal properties exhibited promising results\nwith <i>T</i><sub>max</sub> = 587 °C and <i>T</i><sub>d5%</sub> = 423 °C, rendering these PI/PTFE membranes favorable\nalternatives for prospective telecommunication.