EFFECT OF WATER ON THE ANIONIC-POLYMERIZATION OF ALPHA-METHYL-ALPHA-N-PROPYL-BETA-PROPIOLACTONE

The effect of water on the anionic polymerization of alpha -methyl- alpha -n-propyl- beta -propiolactone was studied by performing kinetic measurements in THF with different amounts of water, at 38. 6 degree C, with tetramethylammonium benzoate as the initiator. The data were treated by assuming that the propagation occurs through free ions, ion pairs, and the corresponding water-solvated species. Analysis of the results leads to the conclusion that the hydrated ion pairs do not contribute to propagation and that the free ions which are in small amounts are less reactive than the ion pairs. Thus the role of water introduced into the medium is to remove a large fraction of the ion pairs from the propagation reaction by hydration.