The activity and the polymer microstructures obtained for polymerizations of four different conjugated dienes catalyzed by CpTiCl3-MAO have been closely compared for a broad temperature range (-45 to +70 °C). Apparent activation energies of 16.1 and 13.1 kcal/mol have been obtained for the poorly chemoselective butadiene and (E)-1,3-pentadiene polymerizations, while an apparent activation energy close to 8 kcal/mol has been obtained for the highly 1,2-syndiospecific polymerization of 4-methyl-1,3- pentadiene. As for (Z)-1,3-pentadiene polymerization, previous experimental evidences of two competing mechanisms have been confirmed. A molecular modeling analysis, comparing three possible polymerization mechanisms for the four considered dienes, contributes to rationalization of the available polymerization results.
Activity and Microstructure Variations with Temperature in Conjugated Diene Polymerizations Catalyzed by CpTiCl3-MAO
COSTABILE, Chiara;GUERRA, Gaetano;LONGO, Pasquale;PRAGLIOLA, Stefania
2005-01-01
Abstract
The activity and the polymer microstructures obtained for polymerizations of four different conjugated dienes catalyzed by CpTiCl3-MAO have been closely compared for a broad temperature range (-45 to +70 °C). Apparent activation energies of 16.1 and 13.1 kcal/mol have been obtained for the poorly chemoselective butadiene and (E)-1,3-pentadiene polymerizations, while an apparent activation energy close to 8 kcal/mol has been obtained for the highly 1,2-syndiospecific polymerization of 4-methyl-1,3- pentadiene. As for (Z)-1,3-pentadiene polymerization, previous experimental evidences of two competing mechanisms have been confirmed. A molecular modeling analysis, comparing three possible polymerization mechanisms for the four considered dienes, contributes to rationalization of the available polymerization results.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
