Low Dielectric Constant Polyimide Hybrid Films Prepared by in Situ Blow-Balloon Method

Insulating materials with a low dielectric constant and a low dielectric loss are in high demand to meet requirements of the continuous miniaturization of electronic devices and high speed information transmission. We fabricated porous polyimide/reduced graphene oxide (PI/rGO) hybrid films with an ultralow dielectric constant and a low dielectric loss via a facile "blow-balloon" method. Poly(ethylene glycol) (PEG) was used as a pore-forming agent by mixing with polyamide acid carboxylate (PAAC) and GO in water. The ternary mixture of PAAC/GO/PEG formed a hydrogel and dried naturally into a xerogel film. Porous PI/rGO films were obtained by in situ thermal pyrolysis of PEG through heating PAAC/GO/PEG hybrid films to 400 °C. The homogeneous porous structure could be regulated easily by adjusting the mass ratio of PEG to PAAC/GO. The porous structure inside the hybrid films prepared by the hydrogel method provided the PI/rGO films with an ultralow dielectric constant (κ) as low as 1.9 and a high ductility with an average elongation at break above 38%. This porous PI/rGO film with an ultralow κ value may be a promising candidate for next-generation interlayer dielectrics.