Research on ring-opening polymerization of ε-caprolactone induced by alkoxy metal compound
Poly(ε-caprolactone)(PCL)was prepared by ring-opening polymerization of ε-caprolactone induced by alkoxy met-al compound(A-17)as initiating species at a reaction temperature of 160 ℃ and time 7 h.The microstructure of the product was analyzed by hydrogen nuclear resonance spectroscopy(1 H-NMR).The changes of the ε-caprolactone monomer conversion(η)and the number average relative molecular mass(Mn)and polydispersity index(PDI)of the products with the reaction time were investigated.And the polymerization kinetics and mechanism were discussed under given conditions.The results showed that the product polymer was proved to be PCL by 1 H-NMR,and there was unreacted ε-caprolactone in the product;the η sharply in-creased at the initial stage of reaction and moderately increased at the later stage of reaction with the extension of reaction time,and the η was 90.16%at 7 h of reaction;the Mn of the product PCL increased from 37 788 to 54 953 and the PDI decreased from 1.55 to 1.31 when the reaction time was prolonged from 5 h to 6 h,and the Mn of the product PCL decreased to 53 778 and the PDI increased to 1.43 when the reaction time was prolonged to 7 h;and the ring-opening polymerization of ε-caprolactone in-duced by A-17 was a first-order reaction,and the reaction mechanism was active anion coordination polymerization.
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