An Investigation of the Resistance of Polyhedral Oligomeric Silsesquioxane Polyimide to Atomic-Oxygen Attack

Abstract

Hybrid inorganic/organic polymers have been prepared by copolymerizing a polyimide having the same chemical repeat unit as Kapton with an open-cage polyhedral oligomeric silsesquioxane (POSS). These POSS/polyimide hybrid polymers are Kapton-like polymers containing POSS nanoparticles that are chemically bound into the polymer chain. Samples of these POSS polyimides, as well as polyimide controls, have been exposed to a hyperthermal 0-atom beam that is produced by a laser-detonation source. Exposed and unexposed surfaces have been characterized by surface profilometry, atomic force microscopy, and X-ray photoelectron spectroscopy The data indicate that the POSS-containing polyimides have significantly lower erosion yields than Kapton, because they form a surface SiO2 layer which passivates the surface and protects the underlying polymer from further 0-atom attack. These results suggest promise for the use of a POSS polyimide polymer as a "drop-in" replacement for Kapton on spacecraft operating in the low-Earth orbital environment.