Design And Synthesis Of Aliphatic Polyester Homopolymers And Block Copolymers

Aliphatic polyester materials have excellent degradability and biocompatibility,which has attracted the attention of many researchers.It has been widely used in life and biomedicine,including food packaging,agricultural plastic film,drug carriers,and genes.Engineering,tissue engineering,surgical sutures,etc.At present,the synthesis of aliphatic polyesters is mainly tin-containing metal catalysts,but its potential high toxicity limits the application of polyester products in biomedicine.The development of new non-toxic/low toxic catalysts is of great scientific importance.This article focuses on the preparation of aliphatic polyesters by the ring-opening polymerization of cyclic lactone monomers catalyzed by green,non-toxic and environmentally friendly catalysts.The following two aspects have been studied:1.The ring-opening polymerization of caprolactone?PCL?and valerolactone?PVL?catalyzed by green and non-toxic FeCl₃:PCL was synthesized by anhydrous FeCl₃ with solution polymerization method,and NMR proved that the monomer can be 100%converted;GPC proved that the molecular weight distribution?PDI?was between 1.08-1.14,which was significantly lower than that of bulk polymerization;the reaction kinetics showed that anhydrous FeCl₃ catalyzed ring-opening polymerization of caprolactone showed controlled properties;we also studied the influence of the reaction temperature,reaction time,reaction solvent,and amount of catalyst on the polymerization;also found that anhydrous FeCl₃ can catalyze the synthesis of PVL.2.Synthesis of polyethylene glycol-b-poly??-butyrolactone??PEG-b-PBL?amphiphilicity block copolymers using cyclic phosphazene base catalyst?CTPB?,potassium methoxide,sodium hydride,sodium alkoxide as catalyst:Nuclear magnetic,infrared,and mass spectrometry demonstrated the successful synthesis of PEG_2k-PBL.Experiments show that when CTPB was used as a catalyst,the interaction between CTPB and DCM weakens the polymerization activity,and the higher the temperature,the stronger the effect.When KOMe and NaH were used as catalysts,there is a multi-activity initiation mechanism.In addition to PEG_2k-PBL,there are a large number of PBL homopolymers;when PEG_2k-ONa is used as a catalyst,the obtained polymer has high controllability of molecular weight,and if urea is added simultaneously In the polymerization system,the PDI of the polymer can be reduced.Based on the previous experiments,the PEG_5k-PBL diblock and the PBL-PEG-PBL triblock copolymer were further synthesized.The PEG-b-PBL amphiphilic block copolymers have good biocompatibility and have potential applications in the fields of drug delivery and tissue engineering and other biomedical fields.