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  • 1
    Electronic Resource
    Electronic Resource
    Time-of-flight secondary ion mass spectrometric analysis of polymer surfaces and additives (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 991-999 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: This paper presents the application of static time-of-flight secondary ion mass spectrometry (ToF-SIMS) to the analysis of polymeric materials, including chemically modified polymers and polymer additives. Throuh the detection of intact functionalized oligomers, analysis of poly(styrene) functionalized with perfluoroalkyl chlorosilane provides confirmation of a successful endgroup termination for a living polymerization. The calculated molecular weight distribution also is in good agreement with chromatrographic results. High mass resolution studies allow monitoring of the hydrogenation of a poly(butadiene) polymer through increases in oligomer mass due to proton addition. The quantitative ToF-SIMS results for the extent of hydrogenation for a specific oligomer are lower than the values averaged over all oligomers as determined by magnetic resonance. The usefulness of ToF-SIMS for determination of trace-level polymer additives is demonstrated for linear low-density poly(ethylene) (LLDPE). Application of a 150 nm thick evaporated Ag pattern enables in situ detection of the five trace additives present in the LLDPE matrix, and also provides information on additive surface migration and surface oxidation. A study of the silver cationization process for the silver-patterned LLDPE surface suggests differences in diffusion and/or ionization processes for two additives. This is confirmed with mass-resolved ion imaging to show the lateral distribution of the silver-cationized signals for various polymer additive molecular ions. Finally, poly(styrene) (Mn = 1300) coated with a continuous silver overlayer is investigated. The ToF-SIMS-determined molecular weight distribution shifts to lower masses, suggesting the greater diffusion of shorter polymer chains through the silver overlayer.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740201210
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Surface characterization of chemically modified (trimethylsily) silicas by 29Si solid state NMR, XPS, and IR photoacoustic spectroscopy (1985)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 7 (1985), S. 196-203 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface reactivity of hydroxyl groups on silica with trimethylchlorosilane (TMCS) is examined using XPS, FTIR-PAS, and solid state NMR. All techniques give responses give responses which can be correlated with increasing TMS surface coverages on Lichrosorb Si 60 silica and provide detection limits of ≤10% of a TMS monolayer. Solid state NMR is particularly suited to examining reactivity differences between geminal and single silanols. Geminal hydroxyl groups are found to be much more reactive. At higher TMS coverages approaching steric limitations (0.5 TMS monolayer), nearly 100% of the geminal sites are reacted as opposed to only 20% of the single sites. The reactive subset of single silanols appears to include hydrogen-bonded (vicinal) groups. A mechanism is postulated to explain the apparent enhanced reactivity of geminal and vicinal silanols.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740070407
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of chemical state on quantitative AES of metal-sulfur compounds (1984)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 6 (1984), S. 15-20 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A quantitative approach to AES is illustrated for various metal-sulfur compounds involving: (a) intensity measurements via integral areas of background subtracted N(E) spectra (including sample probe potential biasing to improve background subtraction); (b) low primary electron dose, pulse-count spectrum acquisition to minimize primary electron beam damage and charging artifacts; (c) corrections to spectral intensity for variations in electron backscattering and inelastic Auger electron mean free path for each metal-sulfur compound matrix; (d) XPS quantitative analysis to correct for differences in surface vs. bulk stoichiometries. Although the above approach results in improved analytical precisions, a residual difference of greater than a factor of 2 remains in the Auger elemental sensitivity factor for sulfur (LMM) in corresponding metal sulfate vs. sulfide compounds. This suggests a chemical state dependent Auger electron yield (core level ionization cross section times the Auger transition probability). Accurate AES quantification, therefore, may require chemical state specific sensitivity factors, particularly for valence shell transitions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740060103
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Polypeptide Conformation and Surface Bonding on Static Secondary Ion Mass Spectra (1996)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 59-67 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: For the first time, the α-helical homopolypeptide poly(γ-benzyl-L-glutamate) (PBLG) was synthesized by solid-phase methods. A 10 residue PBLG sample (10-mer) was prepared which exhibited a β-sheet configuration, and a 15 repeat unit PBLG sample (15-mer) was made which displayed partial α-helical character. Solvent-cast thin films of these peptides were deposited on both gold and silver and analyzed by time-of-flight static secondary ion mass spectrometry (ToF-SSIMS). The PBLG 10-mer spectra consisted of a strong molecular ion (cationized with Na or Ag) and less-pronounced fragments spaced by the benzyl glutamate mass (n-mers) attributed to SSIMS fragmentation. Contrary to this, the PBLG 15-mer did not provide an intact molecular ion, and only low-massn-mer species were observed. Thesen-mers are believed to be a product of SSIMS-induced molecular fragmentation that is enhanced by the peptide α-helical conformation. A disulfide moiety (SS) was also coupled to the 10-mer and 15-mer N-termini (10-merSS and 15-merSS) to provide a functional group for self-assembly on gold. Molecular ions were observed from solvent-cast films of these samples, verifying the presence of the SS cap. However, self-assembled monolayers of these peptides on gold generated weak SSIMS signals which primarily reflect the strong binding of the SS group to the substrate.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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