The Application Of Aluminum, Indium And Group 4 Complexes In Ring-opening Polymerization Of Cyclic Esters

Because of their excellent biocompatible and biodegradable capability, polyesters such as polylactide(PLA) and poly(ε-caprolactone)(PCL) have widely been used in various fields of life. Using metal complexes as catalysts/initiators to initiate the ring-opening polymerization(ROP) of cyclic esters is the major way to prepare these corresponding polymers. A variety of ligands have been used for the synthesis of metal complexes which are used in the ROP of cyclic esters. Among these ligands, phenolate ligands have the most extensive attention because of their easily preparation and low toxicity properties. In this paper, a series of phenolate metal alkoxides have been synthesized and their application as catalysts in the ROP of cyclic esters have been reported.This paper consists of the following chapters:1. A brief review of application of Al, In and Group 4 metal complexes in the ROP of cyclic esters in recent years.2. Synthesis, characterization of bisphenolate aluminum complexes 1-6 and their application in ROP of lactides. These complexes 1-6 show well controlled process and quality of living polymerization in the ROP of lactides.3. Synthesis, characterization of bisphenolate indium complexes 7-12 and their application in ROP of lactides. Comparing to the aluminum complexes 1-6, the indium complexes 7-12 show similar good controllability and much higher reactivity.4. Synthesis, characterization of trisphenolate group 4 complexes 13-15 and their application in ROP of cyclic esters. Zirconium complex 14 and hafnium complex 15 can catalyze the polymerization of cyclic esters to yield polymers with high molecular weight and low polydispersity indexes in several minutes, which makes them to be possibly used in the industrials.