A well-defined catalyst, generated quantitativelyin situsimply by mixing ZrCl4and a salphen ligand was shown to induce the living cationic polymerization of isobutyl vinyl ether.

Appropriate ligand scaffolds in cationic polymerization were screened using various bidentate Schiff base ligand/ZrCl4 initiating systems.

We investigated the cationic polymerization of vinyl ethers using metal complex catalysts with salen and salphen ligands. Metal complexes were generated in situ from the reaction of a ligand and a metal chloride. The choice of a ligand and a central metal was crucial for tuning the catalyst function such as catalytic activity and controllability of the polymerization. Among metal chlorides employed, ZrCl 4 was the most efficient for controlled polymerization. Cationic polymerization of isobutyl vinyl ether (IBVE) proceeded using the salen and salphentype ligand/ZrCl 4 initiating systems, yielding polymers with predetermined molecular weights and narrow molecular weight distributions. Importantly, the structural effects of the complex catalysts were responsible for the polymerization behavior. For example, the polymerization using the salen-type ligand/ZrCl 4 system was much slower than that using the salphen-type ligand/ZrCl 4 system. In addition, the polymerization of IBVE using the salen-type ligand/FeCl 3 system proceeded in a controlled manner, which was in contrast to uncontrolled polymerization using the salphen-type ligand/FeCl 3 system.