OXYGEN PLASMA-RESISTANT PHENYLPHOSPHINE OXIDE-CONTAINING POLYIMIDES AND POLY(ARYLENE ETHER HETEROCYCLE)S .1.

Phenylphosphine oxide-containing polyimides, poly(arylene ether 1,3,4- oxadiazole)s and poly(arylene ether benzimidazole)s were prepared and evaluated for resistance to an oxygen plasma. Thin films of the phenyl phosphine oxide-containing polymers were exposed to a radiofrequency-g enerated oxygen plasma under vacuum along with Kapton(R) HN and polyme rs of similar chemical structure that did not contain the phenylphosph ine oxide group. The stability of the materials to the oxygen plasma w as assessed by monitoring the weight loss of the films as a function o f exposure time. After 23 h oxygen plasma exposure the phenylphosphine oxide-containing polymers exhibited weight-loss rates that were 40 to 145 (1-2 orders of magnitude) times slower than that of Kapton(R) HN, whereas polymers of similar chemical structure that did not contain t he phenylphosphine oxide group exhibited weight-loss rates about 1-3 t imes faster than that of Kapton(R) HN. The changes in surface chemistr y of the exposed films were subsequently examined using X-ray photoele ctron spectroscopy. The phosphorus and oxygen near the surface exhibit ed increases in relative concentration and the photopeaks shifted towa rds higher binding energies. These changes are indicative of the forma tion of phosphate-type species. In addition, limiting oxygen indices w ere calculated from char yields at 850 degrees C in nitrogen utilizing a known method. For the most part, the incorporation of the phenylpho sphine oxide group did not substantially increase the limiting oxygen indices of these experimental polymers.