Ring-Opening Polymerization Of Lactide And Caprolactone By 1,3,5-Triazine-Phosphazene

In order to cope with the increasingly serious environmental pollution,the development of biodegradable materials has become the current solution.Among biodegradable materials,polylactide(PLA)materials and polycaprolactone(PCL)materials have their own advantages,so they have received special attention.They have great application value in biomedical,food packaging and other application fields.When the controlled ring-opening polymerization of lactide monomer and caprolactone monomer is carried out,the use of organic catalysts to catalyze ring-opening is the most important method.However,the use of metal-organic catalysts leads to residual metal elements in polymers,which affects the application of polymers.In order to make up for the defects of metal-organic catalysts,researchers have designed phosphazene base organic catalysts to improve the ring-opening polymerization of cyclic monomers.Phosphazene base organic catalysts have the advantages of simple preparation and high activity,and at the same time overcome the defects of metal-organic catalysts,and have obvious advantages in catalyzing the stereoselective ring-opening polymerization of lactide.The main content of this paper is to construct a binary catalytic system catalyzed by 1,3,5-triazine-phosphazene base catalyst and urea to catalyze the ring-opening polymerization of lactide monomer and caprolactone monomer.The research contents are as follows:1)In this paper,1,3,5-triazine-phosphazene base catalyst and different urea were studied to construct a binary catalytic system,and it was found that when urea 4 and phosphazene base catalyst were combined,a polylactide material with high stereoregularity could be obtained.When the stereoselective ring-opening polymerization of racemic lactide(rac-LA)was catalyzed at room temperature using a phosphazene base catalyst and a urea 4 binary catalytic system,the resulting polymer was characterized by decoupled ~1H NMR.The stereoregularity of the ester is as high as P_m=0.92.The molecular molar mass of the ester is consistent with the theoretical molecular weight and the distribution is narrow.The T_m=190?measured by DSC has good mechanical properties.2)In this paper,the 1,3,5-triazine-phosphazene base catalyst and urea 4 binary catalyst system were studied to catalyze the ring-opening polymerization of caprolactone monomer at room temperature,40°C,60°C and 100°C,and found that the system was in The conversion rate of monomers can reach 92%at 100?,and it is found by GPC characterization that the system has good controllability on the molecular weight of polymers.