Chiral Heterocyclic Amine Lithium Complexes Ring-opening Polymerization Of ?-CL And LA

Polyester materials have been widely used in food packaging,pharmaceutical industry and environmental protection because of their degradability,biocompatibility and good mechanical properties.At present,the chain polyester materials can be obtained by ring-opening polymerization of cyclic esters catalyzed by a series metal complexes,which effectively solves the problems of uncontrollable molecular weight and wide polydispersity index of polymers.The synthesis of organometallic catalysts with high catalytic activity,high stereoselectivity and non-toxicity has always been one of the research hotspots in the field of polymerization chemistry.A series of chiral amino lithium complexes were synthesized by using quinoline as substrate.Their chemical structures was characterized by XRD and NMR,which effectively initiated the ring-opening polymerization of rac-lactide and ?-caprolactone in a controlled manner.The catalytic activity and stereoselectivity of the catalysts were investigated,the mechanism proposal of ring-opening polymerization were analyzed.The main work is divided into three parts:Chapter 1: Giving an account of the development,synthesis methods and applications about polyester materials summarizes;and introducing the polymerization and mechanism of catalysts.Chapter 2: A series of chiral lithium complexes addition products containing quinolyl groups were synthesized by reacting quinoline and 8-methylquinoline with alkyl lithium reagents.The obtained chiral lithium metal complex was characterized and catalyzed by ?-CL and rac-LA ring-opening polymerization.Studies have shown that in the presence of initiator,lithium metal complexes have catalytic activity on ?-CL,and PCL with controlled molecular weight and narrow molecular weight distribution coefficient is obtained,which is consistent with the characteristics of living polymerization.In addition,the chiral lithium metal complex is selective for rac-LA,and in the presence of an initiator,a random polymer is obtained in toluene solvent.The hetero PLA(Pr = 0.66) can be obtainedin dichloromethane solvent,and the polymerization mechanism belongs to the coordination-insertion mechanism;when the initiator is absent,the polymerization mechanism belongs to the anionic polymerization mechanism.Chapter 3: A series of organic base catalysts synthesized from aza heterocyclic(quinoline,2-methylpyridine and 2-methylindole)are directly obtained and used directly to catalyze the ring-opening polymerization of ?-CL and rac-LA.Research shows that the ?-CL ring-opening polymerization is catalyzed in dichloromethane solvent at 25 ?.The organic base catalysts are all catalytically active on ?-CL and rac-LA.In the absence of an initiator,because of the transesterification reaction in the polymerization,obtaining a polymer with an uncontrolled molecular weight and a narrow molecular weight distribution coefficient(1.29-1.40).In the presence of an initiator,the polymerization rate is fast.The PCL which having a controlled molecular weight and a narrow molecular weight distribution,can be obtained by ?-CL;and organic base catalysts catalytic rac-LA opening-ring polymerization makes a hetero isomer PLA(Pr = 0.65),which having a narrow molecular weight distribution.n-Butyl lithium can also catalyze the ring-opening polymerization of rac-LA,and obtain a PLA with a broad molecular weight distribution.