Regular Article | Published:

Ring Opening Polymerization of ε-Caprolactone by Rare Earth Alkoxide–CCl4 Systems


Rare earth alkoxides are highly active initiators for ring opening polymerization of ε-caprolactone in CCl4. The molecular weight of the polymer obtained can be as high as 1.8×105 (Mv) at 60°C in an hour. The influence of solvent, rare earth element, ligand, monomer, and catalyst concentration, as well as the polymerization temperature and time was investigated. A mechanism study by IR, UV, and 1H NMR spectra showed that the polymerization of ε-caprolactone catalyzed by rare earth alkoxides proceeds through a “coordination-insertion” mechanism and selective cleavage of acyl–oxygen bonds of the monomer.


  1. 1

    T. S. Pierre and E. Chiellini, J. Bioactive and Compatible Polymers, 2, 4 (1987).

  2. 2

    C. G. Pitt, T. A. Marks, and A. Schindler, “Biodegradable Drug Delivery Systems Based on Aliphatic Polyesters: Application of Contraceptives and Narcotic Antagonists,” R. Baker, Ed., Academic Press, New York, N.Y., 1980.

  3. 3

    O. Olabisi, L. E. Robeson, and M. T. Shaw, “Polymer-Polymer Miscibility,” Academic, New York, N.Y., 1979.

  4. 4

    K. J. Ivin and T. Saegusa, “Ring Opening Polymerization,” Vol. 1, Elsevier Applied Science, Amsterdam 1984.

  5. 5

    A. Hamitou, T. Ouhadi, R. Jerome, and Ph. Teyssie, J. Polym. Sci., Polym. Chem. Ed., 15, 865 (1977).

  6. 6

    H. R. Kricheldorf, M. Berl, and N. Scharnagl, Macromolecules, 21, 286 (1988).

  7. 7

    M. Endo, T. Aida, and S. Inoue, Macromolecules, 20, 2982 (1987).

  8. 8

    S. J. Mclain, T. M. Ford, and N. E. Drysdale, Am. Chem. Soc., Polym. Prepr., 33, 463 (1992).

  9. 9

    Z. Q. Shen, X. H. Chen, Y. Q. Shen, and Y. F. Zhang, J. Polym. Sci., Polym. Chem. Ed., 32, 597 (1994).

  10. 10

    Z. Q. Shen, Y. Q. Shen, J. Q. Sun, F. Y. Zhang, and Y. F. Zhang, Chin. Sci. Bull., 39, 1005 (1994).

  11. 11

    M. D. Taylor and C. P. Carter, J. Inorg. Nucl. Chem., 24, 387 (1962).

  12. 12

    R. C. Mehrotra and J. M. Batwara, Inorg. Chem., 9(11), 2505 (1970).

  13. 13

    J. V. Koleske and R. D. Lundberg, J. Polym. Sci., Polym. Phys. Ed., 7, 897 (1969).

  14. 14

    C. Jacobs, Ph. Dubois, R. Jerome, and Ph. Teyssie, Macromolecules, 24, 3027 (1991).

  15. 15

    Ph. Dubois, R. Jerome, and Ph. Teyssie, Polym. Bull., 22, 475 (1989).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article


  • Ring Opening Polymerization
  • ε-Caprolactone
  • Rare Earth Alkoxide–Cl4

Further reading