Ion implant-induced change in polyimide films monitored by variable energy positron annihilation spectroscopy
✍ Scribed by U. Myler; X. L. Xu; M. R. Coleman; P. J. Simpson
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 170 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
6FDA-pMDA polyimide membranes were implanted with 140 keV N ϩ ions to fluences between 2 ϫ 10 14 and 5 ϫ 10 15 cm Ϫ2 . Variable energy positron annihilation spectra were taken and spectral features compared to previously reported changes in gas permeability and permselectivity of these membranes as a function of ion fluence. Positron data corroborate the explanation of these changes in terms of molecular damage caused by the implant: for fluences up to about 1 ϫ 10 15 cm Ϫ2 , the concentration of irradiation-induced defects merely increases with implant fluence; while fluences exceeding this threshold value create a second type of positron annihilation site, thereby marking a distinct change in the structure of the polymer, which is responsible for the vast improvement of gas permselectivity data found at the same threshold fluence.