Cationic polymerizations of 2-alkyloxazolines catalyzed by bismuth salts

Abstract

Acidic bismuth salts, such as BiCl3, BiBr3, BiJ 3, and Bi-triflate catalyzed the ring-opening polymerization of 2-methoxazoline (MOZ) in bulk at 100°C, whereas less acidic salts such as Bi2O3 or Bi(III)acetate did not. Bi-triflate-catalyzed polymerizations of 2-ethyloxazoline (EtOZ) were performed with variation of the monomercatalyst ratio (M/C). It was found that the molecular weights were independent of the M/C ratio. The formation of cationic chain ends and the absence of cycles was proven by reactions of virgin polymerization products with N,N-dimethyl-4-aminopyridine or triphenylphosphine. The resulting polymers having modified cationic chain ends were characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry. The polymerization mechanism including chain-transfer reactions is discussed. © 2008 Wiley Periodicals, Inc.