Anionic and ionic coordinative polymerization of epsilon-caprolactone

The polymerization of epsilon -caprolactone initiated by two catalyst syste ms was studied: (1) carbazole-potassium in the presence of 18-crown-6 ether and (2) NdCl3/TBP/TIBA (neodymiumtrichloride/tri-n-butyl-phosphate/triisob utylaluminium) at the molar ratio 1/3/1. For both initiator systems convers ion/time plots were determined and the polymers were characterized by IX, G PC and by 1H- and C-NMR spectroscopy. Polyesters with the highest molecular weight (M(n)congruent to 44 000 g/mol) were obtained for the polymerizatio ns initiated by the carbazole-potassium/18-crown-6 ether system. The featur es of the polymerization initiated by the carbazole potassium/18-crown-6 et her system are discussed on the basis of a simple scheme. The nature of thi s polymerization is non-living. Copyright (C) 2000 John Wiley & Sons, Ltd.