Synthesis, Characterization Of Main-group Metal Complexes And Application In ROP Of Cyclic Esters

Polyesters are among the most versatile synthetic polymers, and they have been widely used as fibers, plastics and coatings. Over the past three decades, polyesters, especially polylactide (PLA), polycaprolactone (PCL) and their copolymers, have attracted considerable attention due to their new biomedical and pharmaceutical applications such as biodegradable surgical sutures and postoperative support pins and splints, or as a delivery medium for controlled release of drugs. The starting materials for biodegradable and bioassimilable PLA are derived from corn, beets, and other annually renewable resources. As the depletion of petrochemical feedstock comes near, the renewable and environmentally friendly polymers are increasingly important for a sustainable future, so such synthesis of biodegradable polyesters possess higher research value. This paper focuses on studying the synthesis of polyesters.This paper consists of four chapters1. It was given a brief review of ring-opening polymerization about cyclic esters.2. Synthesized and characterized one novel aluminium complex like Salen supported by a sulfonamide/Shiff base ligand and the application in ring-opening polymerization of lactide. Experimental results show that aluminium complex is an efficient initiator for the ring-opening polymerization of lactide in controlled fashion, yielding polymers with expectative molecular weight and low polydispersity indexes. Furthermore, aluminium complex has isotactic selectivity for the ring-opening polymerization of rac-lactide.3. Synthesized and characterized a series novel bulky hetero-bimetallic aryloxides supported by EDBPH2 ligand and the application in ring-opening polymerization of lactide. Experimental results show that some hetero-bimetallic aryloxides are an efficient initiator for the ring-opening polymerization of lactide in controlled fashion, yielding polymers low polydispersity indexes and have slight isotactic stereo selectivity for the ring-opening polymerization of rac-lactide.4. Synthesized and characterized a series novel sodium-aluminum complexes and a novel sodium-aluminum inverse crown ether (ICE) complex supported by EDBPH2 ligand and the application in ring-opening polymerization of lactide. Experimental results show that one sodium-aluminum complex is an efficient initiator for the ring-opening polymerization of s-caprolactone. Furthermore, the source of anion oxo has been discussed through different experiments in detail for future research of inverse crown ether to provide some experience.