Molecular structure of silsesquioxanes determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry



Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to deduce the three-dimensional structure of a complex silsesquioxane polymer. Four distinct levels of structure were observed in the mass spectrum. The overall shape of the peak distribution was typical of polymers formed by condensation reactions. The mass separation between major clusters of peaks, each major cluster corresponding to an oligomer with a unique number of repeat units, confirmed that the synthesis proceeded as expected with no side reactions. The mass separation between peaks within a major cluster showed that intramolecular reactions during synthesis resulted in the elimination of water. The loss of water was ascribed to the formation of closed loops in the polymer structure. A simple arithmetic algorithm is presented for identifying these peaks. Autocorrelation techniques were used to determine the number and distribution of intramolecular closed loops per oligomer. This knowledge was used to deduce whether a particular oligomer is branched-linear, ladder, polyhedral, or some combination of these. The single-oligomer isotopic distribution was used to determine that cationization was present from both sodium and potassium ions.


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  1. 1.
    Baney, R. H.; Itoh, M.; Sakakibara, A.; Suzuki, T. Chem. Rev. 1995, 95, 1409–1430.CrossRefGoogle Scholar
  2. 2.
    Voronkov, M. G.; Lavrent’yev, V. I. In Inorganic Ring Systems Boschke, F. L., Ed.; Springer: Berlin, 1982; pp 199–236.Google Scholar
  3. 3.
    Lichtenhan, J. D.; Vu, N. Q.; Carter, J. A.; Gilman, J. W.; Feher, F. J. Macromolecules 1993, 26, 2141–2142.CrossRefGoogle Scholar
  4. 4.
    Lichtenhan, J. D.; Otonari, Y. A.; Carr, M. J. Macromolecules 1995, 28, 8435–8437.CrossRefGoogle Scholar
  5. 5.
    Sellinger, A.; Laine, R. M. Macromolecules 1996, 29, 2327–2330.CrossRefGoogle Scholar
  6. 6.
    Zhang, C.; Laine, R. M. J. Organomet. Chem. 1996, 521, 199–201.CrossRefGoogle Scholar
  7. 7.
    Sellinger, A.; Laine, R. M. Chem. Mater. 1996, 8, 1592–1593.CrossRefGoogle Scholar
  8. 8.
    Haddad, T. S.; Lichtenhan, J. D. Macromolecules 1996, 29, 7302–7304.CrossRefGoogle Scholar
  9. 9.
    Crivello, J. V.; Malik, R. J. Polym. Sci.: Part A: Polym. Chem. 1997, 35, 407–425.CrossRefGoogle Scholar
  10. 10.
    Antonucci, J. M.; Fowler, B. O.; Stansbury, J. W. ACS Polym. Preprints 1997, 38, 118–119.Google Scholar
  11. 11.
    Pan, Q.; Gonzalez, G. B.; Composto, R. J.; Wallace, W. E.; Arkles, B.; Figge, L. K.; Berry, D. H., Thin Solid Films, in press.Google Scholar
  12. 12.
    Gentle, T. E. In Rapid Thermal and Integrated Processing Moslehi, M. M.; Singh, R.; Kwong, D. L., Ed.; SPIE: Bellingham, WA, 1991; pp 146–164.Google Scholar
  13. 13.
    Hacker, N. P. MRS Bull 1997, 22(10), 33–38.Google Scholar
  14. 14.
    Mantz, R. A.; Jones, P. F.; Chaffee, K. P.; Lichtenhan, J. D.; Gilman, J. W.; Ismail, I. M. K.; Burmeister, M. J. Chem. Mater. 1996, 8, 1250–1259.CrossRefGoogle Scholar
  15. 15.
    Gilman, J. W.; Kashiwagi, T.; Harris, R. H.; Lomakin, S.; Lichtenhan, J. D.; Bolf, A.; Jones, P. Proc. Additives98 Conf., in press.Google Scholar
  16. 16.
    Agaskar, P. A.; Klemperer, W. G. Inorg. Chim. Acta 1995, 229, 355–364.CrossRefGoogle Scholar
  17. 17.
    Belu, A. M.; DeSimone, J. M.; Linton, R. W.; Lange, G. W.; Friedman, G. W. J. Am. Soc. Mass Spectrom. 1996, 7, 11–24.CrossRefGoogle Scholar
  18. 18.
    Hensel, R. R.; King, R. C.; Owens, K. G. Rapid Commun. Mass Spectrom. 1997, 11, 1785–1793.CrossRefGoogle Scholar
  19. 19.
    Certain commercial equipment is identified in this article in order to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the items identified are necessarily the best available for the purpose.Google Scholar
  20. 20.
    McEwen, C. N.; Jackson, C.; Larsen, B. S. Int. J. Mass Spectrom. Ion Processes 1997, 160, 387–394.CrossRefGoogle Scholar
  21. 21.
    Birdi, K. S. Fractals in Chemistry, Geochemistry, and Biophysics: An Introduction; Plenum: New York, 1993, Chap 8.Google Scholar
  22. 22.
    Owens, K. G. Appl. Spectrosc. Rev. 1992, 27, 1–49.CrossRefGoogle Scholar

Copyright information

© American Society for Mass Spectrometry 1999

Authors and Affiliations

  • W. E. Wallace
    • 1
  • C. M. Guttman
    • 1
  • J. M. Antonucci
    • 1
  1. 1.Pglymers DivisionNational Institute of Standards and TechnologyGaithersburgUSA

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