Fluorinated polyimide with enhanced ultraviolet-resistant radiation via a self-sacrificial strategy

High-performance polyimide (PI) films with excellent ultraviolet (UV)-resistant radiation and low dielectric constant (k) properties are ideal spacecraft antenna substrates in space applications. However, conventional commercial PI films like Kapton® applied in the aerospace field are inevitably subjected to the harsh UV radiation environment, leading to their structural damage and performance failure. Herein, a type of “self-sacrificial” micro-branched crosslinked PI films were fabricated by employing tris(4-aminophenyl)amine (TAPA) intrinsically containing the C-N bonds to crosslink linear pure fluorinated PI (FPI), where TAPA functioned as the dual roles of crosslinker and creating “self-sacrificial” local deep traps of C-N bonds in crosslinked sites. Consequently, abundant local deep traps of C-N bonds in crosslinked sites could capture energy from UV-rays to prevent the destruction of PI molecular main chains, thus the crosslinked FPI-TAPA films exhibited better UV-resistant radiation properties than that of pure FPI films and commercial PI films. And the crosslinked film showed least k of 2.53 and least dielectric loss of 0.006 at frequency of 1 MHz owing to the introduction of micro-branched crosslinked structure. Additionally, a high breakdown strength of 522 MV/m, as well as a high tensile modulus of 3.03±0.07 GPa, was achieved, much better than the value of pure FPI film. This work provides a novel and facile approach to fabricate high-performance PI films with excellent UV-resistant properties, exhibiting great potential application in aerospace and microelectronics industries.