Catalyst behavior of aluminum alkyl systems in the polymerization of cyclic ethers

The polymerization of cyclic ethers, especially of epichlorohydrin, by AlEt3 and AlEt3/H2O system was studied. From the effects of solvent (CH2Cl2) and of a small amount of pyridine upon the copolymerization of epichlorohydrin with tetrahydrofuran, it has been assumed that there are at least two active species in these polymerizations: one is responsible for cationic polymerization and the other is for coordinate anionic polymerization. This assumption has been supported by the stoichiometric reactions of these catalysts with epichlorohydrin and also by the behavior of the alkoxide modified systems of AlEt3 and AlEt3/H2O.