Atomic oxygen-resistant and transparent polyimide coatings from [3,5-bis(3-aminophenoxy)phenyl]diphenylphosphine oxide and aromatic dianhydrides: Preparation and characterization

Abstract A novel meta -substituted aromatic diamine, [3,5-bis(3-aminophenoxy)phenyl]diphenylphosphine oxide ( m -BADPO) was synthesized by the Williamson reaction of 3,5-difluorophenyldiphenylphosphine oxide (DFPPO) and meta -aminophenol. The diamine was then polymerized with several commercially available aromatic dianhydrides to afford a series of aromatic polyimides (PI-1–PI-4). The meta -substituted molecular skeleton and the pendant bulky phenylphosphine oxide (PPO) group endowed the PIs many desired properties for their potential applications in space environments. For instance, the solubility of the PIs was enhanced due to the synergic effects of meta structure and the bulky PPO groups, making it possible to fabricate the PI films via solution procedure. The films exhibited flexible and tough natures with light color and high transparency in the visible light region. The transmittance up to 87% at 400 nm was achieved in the films. The atomic oxygen (AO) degradation behavior of the PI films in the ground-based simulation facility was investigated. The preliminary X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) measurement results indicated that the PI films exhibited good durability in AO-rich environments. Inert phosphorous-containing protecting layer might form at the surface of PI film during AO exposure. In addition, the intrinsic merits of typical high-performance PIs were maintained in the present polymers.