Bimetallic aluminum alkyl complexes as highly active initiators for the polymerization of ε-caprolactone

Abstract

Two dinuclear aluminum alkyl complexes supported by a piperazidine-bridged bis(phenolato) group were prepared, and both complexes exhibited extremely high activity for the ring-opening polymerization of ε-caprolactone. In the presence of benzyl alcohol (BnOH), the polymerization accelerated dramatically.

Cubane‐Type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring‐Opening Polymerization Studies of rac‐Lactide and ε‐Caprolactone

“…Multinuclear metal catalysts, such as yttrium, rare earths, group IV, iron, magnesium, copper, zinc, and aluminum have received enormous attention for ROP of cyclic esters. Tolman and co‐workers reported that the polymerization rate for LA with dinuclear zinc catalysts compares favourably to the fastest catalysts .…”

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

“…This observation is similar to that reported by Chmura et al 84 for Ti(IV) complexes of bis(phenolate)s, but in contrast to the aluminum systems reported by other authors where less sterically demanding ligands afforded more effective initiators. 85,86 However, by comparing the activity of the methyl complexes with the chloride complexes, the latter showed lower activity and produced polymers with different properties. This trend has also been observed by others.…”

Dimethylaluminum complexes bearing a chiral diketiminate ligand: Synthesis, characterization and ring-opening polymerization of ε-caprolactone

“…Among the reported initiators, organoaluminum complexes have attracted much attention because they have a good control over the polymerization reaction [7] and low toxicity [8]. However, few studies have involved the alkyl aluminum complexes as the initiator for the ROP of ε-CL without the presence of alcohol, because these complexes usually showed no or very low activity towards this polymerization [9], and most of them got a broad molecular weight distribution during the reaction [9,10].…”

“…Although plenty of various ligands are employed in the alkyl aluminum initiators [9][10][11], aluminum complexes bearing N,N′-substituted β-diketiminate ("nacnac") ligands and their application in ROP of cyclic esters are still less investigated [10c]. The β-diketiminate ligands have gained increasing interest due to their suitability as fine-tuned spectator ligands by variation of the steric and electronic properties of the N,N′-substituents [12,13].…”