ToF-SIMS Determination of Molecular Weights from Polymeric Surfaces and Microscopic Phases
✍ Scribed by Galuska, Alan A.
- Book ID
- 102647263
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 509 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0142-2421
No coin nor oath required. For personal study only.
✦ Synopsis
Time-of-Ñight (ToF) SIMS spectra were acquired from a variety of elastomer and thermoplastic molecular weight (MW) standards : polyisoprene (PIP), 1,4-polybutadiene (PBD), polyisobutylene (PIB), polyethylene (PE), polystyrene (PS), polypropylene (PP) and poly(1-butene) (P1-B). These spectra were then examined to determine any correlation between relative ion intensities and MW. In all cases, the relative intensities of protonated monomer (monomer + H) ions were particularly sensitive to MW. These monomer + H relative ion intensities were fairly constant at MWs above 20 000, but increased dramatically and contiguously as the MW of the polymer decreased below 20 000. For all of the polymers examined, the variation of monomer + H ion intensities with MW could be Ðt using the general relationship : Relative monomer + H ion intensity = M(MW/1000)E + B, where M is the slope, B is the ion ratio intercept and E is an exponent with values between Ô0.5 and Ô0.6. Using this general relationship, ToF-SIMS MW calibration lines were developed for PIP, PBD, PIB, PE, PS, PP and PI-B. These calibration lines could be used to determine the presence and approximate MW of low-MW (O20 000) polymer, but could not distinguish the MWs of high-MW (P20 000) polymers. The technique was applied to the analysis of MWs on PP Ðbers. Moreover, the MW calibrations were shown to be useful for determining the presence of unknown low-MW waxes and additives on polymeric surfaces.