THE EFFECT OF LOW-EARTH-ORBIT ATOMIC OXYGEN EXPOSURE ON PHENYLPHOSPHINE OXIDE-CONTAINING POLY(ARYLENE ETHER)S

Unoriented thin films Of phenylphosphine oxine-containing poly(arylene ether)s were exposed to low Earth orbit aboard the space shuttle Atla ntis (STS-51) as part of a flight experiment designated Limited Durati on Candidate Exposure (LDCE 4-5). The samples were exposed to primaril y atomic oxygen (similar to 7 x 10(19) atoms/cm(2)). Based on post-fli ght analyses using atomic force microscopy, X-ray photoelectron spectr oscopy, gel permeation chromatography and weight loss data, it was pro posed that atomic oxygen exposure of these materials produces a phosph ate layer at the surface of the samples, apparently by the reaction of atomic oxygen with the phosphorus in the polymer backbone. Ground-bas ed oxygen plasma exposure experiments have previously shown that this phosphate layer provides a barrier against further attack by atomic ox ygen [1]. The results obtained from these analyses compare favorably w ith those obtained fi om samples exposed to an oxygen plasma in ground -based exposure experiments [1]. (C) 1998 John Wiley & Sons, Ltd.