LIVING POLYMERIZATION OF METHACRYLIC ESTERS WITH ALUMINIUM PORPHYRIN INITIATORS. AXIAL LIGAND EXCHANGE ACTIVITIES OF ALKYL- AND ENOLATE-ALUMINIUM PORPHYRINS IN RELATION TO THE POLYMERIZATION MECHANISM

Article abstract of DOI:10.1002/poc.610080408

Polymerization of methacrylic esters such as benzyl methacrylate using as initiator an-equimolar mixture of methylaluminium 5,10,15,20-tetraphenylporphine <(TPP)AlMe> and 2,7,12,17-tetramethyl-3,8,13,18-tetramethylporphine <(EtioP)AlMe> proceeded from both initiators, affording a unimodal polymer of narrow molecular weight distribution, although the reactivities of (TPP)AlMe and (EtioP)AlMe are very different from each other. 1H NMR studies on a mixture of two different (porphinato)aluminium enolates, the growing species, and a mixture of a (porphinato)aluminium enolate and an alcoholate, in the absence and presence of methyl methacrylate (MMA or MMA-d8), indicated an acyclic transition state polymerization mechanism by the participation of two aluminium porphyrin molecules, where the growing species always exchange their enolate ligands whenever it grows.