Synthesis,Characterization Of Tetraphenoxide Multi-Metal Complexes And Application In ROP Of Cyclic Esters

Biodegradability, biocompatibility, and permeable properties of aliphatic polyesters, such as poly(e-caprolactone) (PCL) and poly(lactide) (PLA), and their copolymers show potential applications in the medical field as biodegradable surgical sutures or a delivery medium for controlled release of drugs. The major polymerization method used to synthesize these polymers has been the ring-opening polymerization (ROP) of CL/LA and functionally related compounds. Therefore, there has been increasing interest in the development of efficient catalytic systems for the preparation of PCL and PLA. Though several effective initiators that initiate ROP of lactones/lactide have been reported, this paper focuses on studying the synthesis of polyesters. We can privide some useful information to the research of ring-opening polymerization and broaden its applications in packaging and fiber technology.This paper consists of four chapters1. A brief review of ring-opening polymerization about cyclic esters was given.2. Series of bulky homobimetallic complexes supported by tetraphenoxide were synthesized and characterized and were applied in ring-opening polymerization of cyclic esters. Experimental results show that tetraphenoxide main group element homobimetallic complexes are efficient initiators for the ring-opening polymerization of lactide or lactone in controlled fashion and yielding polymers low polydispersity indexes.3. Synthesized and characterized a series novel heterobimetallic complexes supported by tetraphenoxide and the application in ring-opening polymerization of lactide. Experimental results show that these alkali-Al/Mg bimetallic complexes including the expected bulky coordination anion and alkali cation show high catalytic activities to the ROP of lactide.4. A well-defined DCM-PLA polymer system was synthesized by the ring-opening polymerization of L-lactide with Sn(Oct)2 as catayst and DCM as initiator which is activated by Sn(Oct)2. The fluorescence properties of DCM-PLA materials exhibit tunable photoluminescence by varying polymer chain lengths. The biodegradable and biocompatible dye system can overcome the problems of heterogeneity, aggregation, depigment and photodegradation, and show promise for imaging and sensing applications.