Ring-opening Polymerization Of Thionophosphoester And Glycolide Monomers Catalyzed By Organic Base-(Thio)urea

As one kind of novel polymer material with good biocompatibility and biodegradability,polyester has been widely used in biological medicine,genetic engineering and packaging materials.Nowadays,ring-opening polymerization of cyclic esters is a common method to synthesize the polyester materials.The polymer structure of polyester could be modified by varying the structure of the used monomer.Hence,this dissertation investigated two types of monomers(phosphate and substituted glycolide),explored the effect of two-component synergistic catalytic system on its ring-opening polymerizations,and synthesized new polyester materials with controllable molecular weight,good molecular weight distribution,higher isotactic regularity and well-defined structure.It is mainly divided into the following two parts:1.To solve the problem of strong hydrophobicity and instability of poly(phosphoester)s,new type of phosphate monomer 2-phenyl-2-thiono-1,3,2-dioxaphospholane(PTP)was synthesized for the first time by converting the phosphorus oxygen double bond to phosphorus sulfur double bond and introducing aromatic group phenyl into the side chain substituent.Using 1,8-diazabicycloundecano-7-ene(DBU)and thiourea as synergistic organic catalytic system,ring-opening polymerization of PTP monomer was achieved,delivering poly(PTP)s with well-defined structure,relatively narrow molecular weight distributions(1.14-1.20)and high molecular weight(up to 45.2 kg/ml).Kinetic experiment and chain extension experiment confirmed the controlled/living nature of the ROP process.2.To improve the toughness and elasticity of polylactic acid,three different substituted glycolide monomers such as EtGL,BnGL etc.were synthesized and applied to the ring-opening polymerizations.Using organic base N-heterocyclic olefins and urea as the synergistic catalyst,all three monomers showed high reactivity for ring-opening polymerization.The micro sequence structure of the three polymers were clearly analyzed by 1H NMR,and a set of quantitative calculation method for isotacticity of the polymers was determined.An isoselective and controlled ring-opening polymerization of EtGL was achieved,which showed that the highest Pm is up to 0.94.Moreover,MALDI-TOF analysis determined that the obtained polymer is a linear structure and no side reaction occurs during the polymerization process.