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Aggregation in the Anionic Polymerization of Hexamethylcyclotrisiloxane with Lithium Counterion

Polymer Journal volume 19, pages 531538 (1987) | Download Citation

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Abstract

The kinetics of the polymerization of hexamethylcyclotrisiloxane D3 initiated by lithium 2,4,4-trimethyl-1-pentanolate (CH3)3CCH2CH(CH3)CH2OLi in THF solution in the range 0–60°C has been investigated. Polymerization was essentially first order in respect to monomer. Independent of the temperature in the range from 0 to 60°C, the external order of the rate with respect to initiator changed from 0.25 to 0.33 by changing the initiator concentration from 10−1 M to 10−3 M. This change indicates a change in the degree of aggregation from 4 to 3 of the propagation-active siloxanolate groups. The presence of aggregates and the change in their degree of aggregation from 4 to 3 has been independently and quantitatively confirmed by viscometry carried out before and after quenching the living D3 polymerization by Men−4SiCln (n=1–4) and Cl2SiMeCH2CH2MeSiCl2. Evidently most of the siloxanolate end groups are organized into aggregates whose size is controlled by the concentrations of the siloxanolate groups in the range from 10−3 to 10−1 M but insignificantly by the temperature from 0 to 60°C. Propagation is due to a relatively small proportion of active unaggregated ion pairs.

References

  1. 1.

    L. Wilczek, M. K. Mishra, and J. P. Kennedy, in preparation.

  2. 2.

    , Rubber Chem. Technol., 42, 71 (1969).

  3. 3.

    , , , , and , Rubber Chem. Technol. 49, 303 (1976).

  4. 4.

    , “Anionic Polymerization: Principles and Practice,” Academic Press, New York, 1983.

  5. 5.

    , Adv. Polym. Sci., 49, 1 (1983).

  6. 6.

    , “Anionic Polymerization” in “Encyclopedia of Polymer Science and Engineering,” Vol. 2, 2nd ed, Wiley-Interscience, New York, 1985, p 1.

  7. 7.

    , “Cyclic Siloxanes” in “Ring-Opening Polymerization,” Vol. II, K. J. Ivin and T. Saegusa, Eds., Elsevier, London, 1984, Chapter 14, p 1109.

  8. 8.

    and , Makromol. Chem., 176, 2999 (1975).

  9. 9.

    , Am. Chem. Soc., Symp. Ser., 166, 283 (1981).

  10. 10.

    , , and , J. Am. Chem. Soc., 76, 249 (1954).

  11. 11.

    and , J. Am. Chem. Soc., 77, 1405 (1955).

  12. 12.

    and , Trans. Faraday Soc., 62, 701 (1966).

  13. 13.

    , , , and , Macromolecules, 3, 327 (1970).

  14. 14.

    and , J. Polym. Sci., Polym. Chem. Ed., 14, 729 (1976).

  15. 15.

    , , and , J. Polym. Sci., Polym. Chem. Ed., 14, 743 (1976).

  16. 16.

    , , and , J. Polym. Sci., Polym. Chem. Ed., 12, 1089 (1974).

  17. 17.

    , Polym. Prepr., Am. Chem. Soc., Div. Polym. Chem., 8(1), 474 (1967).

  18. 18.

    and , Eur. Polym. J., 4, 439 (1968).

  19. 19.

    , , and , Eur. Polym. J., 7, 1421 (1971).

  20. 20.

    , , and , Adv. Polym. Sci., 56, 1 (1984).

  21. 21.

    , , and , Collect. Czech. Chem. Commun., 33, 3245 (1968).

  22. 22.

    and , J. Am. Chem. Soc., 81, 6145 (1959).

  23. 23.

    and , Trans. Faraday Soc., 62, 701 (1966).

  24. 24.

    and , Macromolecules, 7, 552 (1974).

  25. 25.

    , Adv. Polym. Sci., 30, 89 (1979).

  26. 26.

    , , , and , J. Polym. Sci., 57, 471 (1962).

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  1. Institute of Polymer Science, The University of Akron

    • Lech Wilczek
    •  & Joseph P Kennedy

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https://doi.org/10.1295/polymj.19.531