Lactone Polymerization
William H. Sharkey · ACS symposium series · 1985
The polymerization of pivalolactone, α, α-dimethyl-β-propiolactone, is a remarkably easy anionic, ring-opening reaction that takes place rapidly and completely in organic media at mild temperatures. Since it appears to be similar to other β-lactones in its polymerization and the properties of its polymers have been more widely studied than those of other β-lactone polymers, the formation and properties of polypivalolactone will be emphasized in this discussion. Early studies on pivalolactone ( 1, 2 ) established that its polymerization is initiated by tertiary amines and phosphines. The reaction was visualized as occurring in two steps. The formation of a macrozwitterion by attack of the nucleophile on the methylene group of PVL has been supported by NMR and chemical studies on propiolactone. By these means Maskevich, Pakhomeva, and Enikolopyan ( 3 ) who used triethylphosphine and Mathes and Jacks ( 4 ) who used triethylamine, obtained evidence for the initiation reactions. In addition, Mathes and Jacks ( 5 ) used betaine,