Synthesis Of Aluminum Aminoquinoline Complexes And Its Catalytic Activity For Ring-opening Polymerization Of ε-caprolactone

Polycaprolactone（PCL）has important applications in biomedicine,plastic films,industrial materials and so on because of its good biodegradability and biocompatibility.The research shows that using metal complexes to synthesize PCL is a simple and efficient method.In the past few years,many researchers have studied ROP catalyzed by metal complexes containing aluminum,and found that the activity of the catalytic and the products properties will be greatly affected by the environment of ligands.Therefore,we continued to study the new catalyst model,prepared a series of aluminum complexes based on aminoquinoline ligands,and used them for ring-opening polymerization ofε-caprolactone.The main research contents and structure are briefly described as follows:Five new aminoquinoline metal aluminum complexes were synthesized by the reaction of metal aluminum compounds with imino-quinoline ligands,and a series of characterization were carried out.The nuclear magnetic resonance spectrum and X-ray diffraction show that the aminoquinoline metal aluminum complex is directly synthesized by the reaction of imino-quinoline compound with Al Me₃ and the methyl transfer from aluminum to imine carbon atom.Using the aminoquinoline metal aluminum compound to catalytic ring-opening polymerization ofε-caprolactone was studied.These aminoquinoline metal aluminum compounds showed remarkable reactivity to the ROP ofε-caprolactone in the presence of Bn OH.When CL:Al:Bn OH=500:1:1,the monomer conversion rate could reach83-95%within 5 minutes,and the molecular weight（M_n）and dispersibility（?<1.2）of the polymer were also well controlled.When the ratio of CL:Bn OH was further increased to 2000,polycaprolactone with molecular weight as high as 129 k Da was successfully synthesized.The molecular weight distribution was 1.16,which indicated that the polymerization reaction was still well controlled.When CL:Al:Bn OH=2000:1:20,the metal aluminum complex shows the characteristics of typical living polymerization.We also studied the influence of ligand structure.The kinetic study showed that electron-withdrawing groups would reduce the activity of the complex,and groups with large steric hindrance would inhibit the reaction activity.