Kinetics and mechanism of polymerization of n-butyl vinyl ether initiated by dichloroalane (AlHCl2):: A new cationic initiating system

The carbocationic polymerization of n-butyl vinyl ether (BVE) using the new LiAlH4/AlCl3 initiating system is reported. The polymerizations were carried out in diethyl ether (Et2O), and in a mixture of diethyl ether and dichloromethane (1:1 v/v) at various temperatures, and the kinetics of the polymerizations was studied. The rate constants, the temperature dependence of the rate constants, and the kinetic order of the reactants were determined. The end groups of the polymers were characterized by H-1 NMR and MALDI-TOF MS methods. Three different interconvertible end groups, i.e., heteroacetal, homoacetal, and aldehyde, were observed. The tacticity of the polymers formed was determined by C-13 NMR. On the basis of detailed kinetic and structural investigations, a direct initiation mechanism for the polymerization is proposed.