A number of simple aliphatic hydrocarbon polymers have been studied by static SIMS. The low-mass positive spectra reflect structural dflerences in the polymeric structure, which result in characteristic fingerprint spectra. Unsaturation and differences in branching lead to very distinct spectral features which show promise for the application of SIMS as an analytical technique in polymer-related areas. An attempt is made to interpret the spectra in terms of molecular structure, fragmentation mechanisms and ion stabilities. The chemical nature of ion beam damage in PE and PP was studied to some extent.
The monolayer behavior of some poly(methacry1ates) with short ester side chains (methyl, ethyl, and isobutyl) is studied as a function of the tacticity. In all cases, the isotactic polymers are observed to form expanded monolayers, whereas the syndiotactic materials yield more condensed monolayers. These observations are attributed to differences in the lateral cohesive interactions of the segments in the monolayer, which again can be correlated with the difference in spatial orientation of the ester groups with respect to the backbone and the airwater interface. The anomalous temperature dependence of the isotactic polymers (a contraction of the monolayers at higher temperatures) can be interpreted in terms of an enhancement of theae lateral cohesive interactions (a decrease of the solvent quality of the environment). Surface potential measurements yield results which appear to be in agreement with the interpretation of the monolayer isotherm data and also illustrate the monolayer crystallization process proposed for isotactic PMMA in a previous publication. Isotactic poly(methacrylic acid) is observed to form stable monolayers on a pure water subphase, in contrast to syndiotactic poly(methacry1ic acid).
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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Among the surface-sensitive spectroscopies used to characterize clean and surface-modified polymers, one technique has rather recently emerged as a very promising complementary tool. High-resolution electron energy loss spectroscopy, or electron-induced vibrational spectroscopy, has potentially all the attributes of the well-known optical (infrared and Raman) spectroscopies; it clearly adds to X-ray photoelectron spectroscopy the possibilityto go beyond surface elemental and chemical analysis and to unravel the molecular structure of an extremely thin surface layer of a polymer. This ultrahigh vacuum spectroscopy is shown here to gather information from the last 25 A or so of the polymer surface, as deduced from the analysis of sandwich layers of normal and perdeuterated PMMA Langmuir-Blodgett films. Four case studies of molecular-type information are presented, illustrating (1) the preferential surface segregation of CH, chain ends on a crystalline polyethylene, (2) selective surface segregation and dynamics of deuterated material in mixtures of normal and deuterated polystyrenes, (3) tacticity induced molecular orientation of PMMA's and polystyrene, and (4) metalization induced molecular reorientation on the surface of polyimide films.
Positive static SIMS spectra of poly(methylmethacry1ate) (PMMA) and perdeuterated PMMA have been compared. The usefulness of this approach for the distinction between hydrocarbon and oxygen-containing secondary ions is demonstrated. For example, a major characteristic fragment like the one at 69 amu, which had been tentatively identified as CSH9+ by other authors, was shown to be C,HSO+.
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