OXYGEN PLASMA-RESISTANT PHENYLPHOSPHINE OXIDE-CONTAINING POLYIMIDES AND POLY(ARYLENE ETHER HETEROCYCLE)S .2.

Phenylphosphine oxide-containing poly(arylene ether imide)s, poly(aryl ene ether quinoxaline)s, poly(arylene ether benzoxazole)s and poly(ary lene ether benzothiazole)s were prepared by reacting the appropriate d ifluoro heterocyclic compound with bis(4-hydroxyphenoxy-4'-phenyl)phen ylphosphine oxide. The polymers exhibited glass transition temperature s from 209 to 255 degrees C and inherent viscosities from 0.35 to 1.34 dl g(-1) Thin-film tensile properties measured at room temperature an d 177 degrees C exhibited tensile strengths of 10.2-15.8 and 6.0-9.0 k si (similar to 70.3-108.9 and similar to 41.4-62.1 MPa), respectively, and tensile moduli of 340-381 and 204-365 ksi (similar to 2.34-2.63 a nd similar to 1.41-2.52 GPa), respectively. Unoriented thin films of t hese phenylphosphine oxide-containing polymers were subsequently expos ed to a radiofrequency-generated oxygen plasma under vacuum along with Kapton(R) HN. To assess the resistance of the materials to the oxygen plasma, the weight losses of the films were monitored as a function o f exposure time. Phenylphosphine oxide-containing poly(arylene ether b enzoxazole)s and poly(arylene ether benzothiazole)s exhibited weight-l oss rates that were 38-190 (1-2 orders of magnitude) times slower than that of Kapton(R) HN. Phenylphosphine oxide-containing poly(arylene e ther quinoxaline)s exhibited weight-loss rates only slightly slower (1 -7 times) than those of Kapton(R) HN. The changes in surface chemistry of the exposed films were subsequently examined using X-ray photoelec tron spectroscopy. In most cases, the phosphorus and oxygen near the s urface exhibited increases in relative concentration and the photopeak s shifted towards higher binding energies. These changes are indicativ e of the formation of phosphate-type species. In addition, their limit ing oxygen indices were calculated from char yields at 850 degrees C i n nitrogen utilizing a reported method. For the most part, the incorpo ration of phenylphosphine oxide groups did not substantially increase the limiting oxygen indices.