In situ oxygen atom erosion study of a polyhedral oligomeric silsesquioxane-polyurethane copolymer
In situ oxygen atom erosion study of a polyhedral oligomeric silsesquioxane-polyurethane copolymer
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DOI：
10.1163/156856101317048707
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发表时间：
2001-01-01
影响因子：
2.3
通讯作者：
Phillips, SH
中科院分区：
文献类型：
--
作者：
Hoflund, GB;Gonzalez, RI;Phillips, SH
多面体低聚倍半硅氧烷-聚氨酯共聚物的表面已经使用X射线光电子能谱在暴露于由超热氧原子源产生的氧原子的增量注量之前和之后原位表征。数据表明，原子氧最初攻击包围多面体低聚倍半硅氧烷的环戊基。笼最可能导致CO和/或CO2和H2O从表面形成和解吸。近表面区域的碳浓度从72.5at.%对于刚进入的表面为37.8at.%在2.0 x 10（13）O atom/cm（2）-s的通量下暴露63 h后，氧和硅的浓度随着暴露于O原子通量的增加而增加。氧浓度从18.5at.%对于输入的样品为32.6at.%暴露63小时后，硅浓度从8.1原子%增加到11.1原子% 63 h后，数据揭示了表面上二氧化硅层的形成，其用作保护屏障，防止下面的聚合物随着暴露于O原子通量的增加而进一步降解。
The surface of a polyhedral oligomeric silsesquioxane-polyurethane copolymer has been characterized in situ using X-ray photoelectron spectroscopy before and after exposure to incremental fluences of oxygen atoms produced by a hyperthermal oxygen atom source, The data indicate that the atomic oxygen initially attacks the cyclopentyl groups that surround the polyhedral oligomeric silsesquioxane. cage most likely resulting in the formation and desorption of CO and/or CO2 and H2O from the surface. The carbon concentration in the near-surface region is reduced from 72.5 at.% for the as-entered surface to 37.8 at.% following 63 h of O-atom exposure at a flux of 2.0 x 10(13) O atom/cm(2)-s. The oxygen and silicon concentrations are increased with incremental exposures to the O-atom flux. The oxygen concentration increases from 18.5 at.% for the as-entered sample to 32.6 at.% following the 63-h exposure, and the silicon concentration increases from 8.1 to 11.1 at.% after 63 h. The data reveal the formation of a silica layer on the surface, which serves as a protective barrier preventing further degradation of the polymer underneath with increased exposure to the O-atom flux.