AN INVESTIGATION OF THE RESISTANCE OF POSS POLYIMIDE TO ATOMIC OXYGEN ATTACK

Hybrid inorganic/organic polymers have been prepared by copolymerizing a polyimide having the same chemical repeat unit as Kapton with polyhedral oligomeric silsesquioxanes (POSS). These POSS/polyimide hybrid polymers are essentially Kapton-like polymers containing POSS nanoparticles that are chemically bound to the polymer chain. Samples of these POSS polyimides, as well as polyimide controls, have been exposed to a hyperthermal O-atom beam that is produced by a laser­ detonation source. Exposed and unexposed surfaces have been characterized with the use of x-ray photoelectron spectroscopy, atomic force microscopy, and surface profilometry. The data indicate that the POSS-containing polyimides have significantly lower erosion yields than Kapton, most likely because they form a surface SiO 2 layer which passivates the surface and protects the polymer from further O-atom attack. These results suggest promise for the use of POSS polyimide polymers as “drop-in” replacements for Kapton on spacecraft operating in the low-Earth orbital environment.