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  • Wiley-Blackwell  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 387-394 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The desorption of emulsifiers from the particle surface of polystyrene latexes prepared by emulsion polymerization has been studied by Time-of-Flight Secondary Ion Mass Spectrometry (ToF SIMS). Two polystyrene latexes prepared with respectively sodium dodecyl sulphate and sodium dodecylbenzene sulphonate as emulsifiers were compared. It has been shown that the quasi-molecular, parent ions and the characteristic fragments of the emulsifiers can easily be observed in positive and negative ToF SIMS. But these ions are more sensitive in the negative mode. The results have shown that after extensive purification with mixed-bed ion-exchange resins, the emulsifier was totally absent on the latex prepared with sodium dodecyl sulphate and that only traces of the emulsifier exist on the latex prepared with sodium dodecylbenzene sulphonate. These results suggest that strong acid emulsifiers can be desorbed by mixed-bed ion-exchange resins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The first principles model (FPM) has been compared with other quantitative approaches by using many standard samples. As a first step, the applicability of the theoretical dependence of IC 1s/ICKVV on the reduced thickness (x) of a hydrocarbon surface contamination layer was checked and shown to be approximately correct only in the middle range of x. A semi-empirical relation between IC 1s/ICKVV and x has been developed. The advantage of this relation over that previously developed in the literature is that the transmission function of our spectrometer is well characterized. The reduced thickness calculated using this semi-empirical relation has been shown to be close to the real value. The comparison of atomic ratios calculated using these quantitative approaches has shown that the best approach is the FPM. For the samples investigated in this work, the introduction of the anisotropy parameter L is not necessary: in most cases, the influence of L is smaller than the observed errors; and in certain cases where the difference of L values is large, more consistent results are obtained when L is ignored. The FPM approach provides consistent results not only when an inter-comparison is made between different spectrometers but also when, within a given machine, the analysis conditions are varied. The accuracy of this approach is relatively good (with errors 〈15%) and holds true even when comparing peaks separated by more than 1000 eV. Finally, the comparison of results obtained with different previously determined transmission functions has allowed us to test the applicability of the methods used for the determination of these transmission functions (see Part I).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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