Preparation Of Polyester-amine Microspheres Based On Amine-ene Reaction Through Precipitation Polymerization And Their Application Thereof

In this paper,acetonitrile was used as the solvent and piperazine(PA)and trimethylolpropane triacrylate as the monomers.Basing on the aza-Michael addition,monodisperse poly(ester-amine)(PEA)microspheres were preparedt through gradual precipitation polymerization.The experimental results showed that uniform PEA microspheres can be prepared when the temperature is 4 °C,the monomer content is 6 wt%,and the reaction time is 12 h.In addition,poly(aspartamide)s(PAS)microspheres were prepared in acetone/tetrahydrofuran mixed solvent using PA and 4,4-bismaleimide diphenylmethane as monomers.The morphology of PAS microspheres could be controlled by changing the mass ratio of acetone and tetrahydrofuran,reaction temperature and the ratio of two monomers.The experimental results showed that PAS microspheres with pore structure could be prepared at temperatures below 10 °C or the mass of the mixed solvent acetone/tetrahydrofuran was less than 5/5;solid PAS microspheres with clean surfaces could be prepared at temperatures higher than 40 °C.Carbon-carbon double bonds could be located on the surface of the microspheres by changing the molar ratio of the amine group and carbon-carbon double bond,which provides a good active site for the modification.The double bond content on the surface of PEA microspheres and PAS microspheres was 0.28 mmol/g and 0.51 mmol/g,respectively,by adding ?-phenethylamine to the microsphere suspension system.The carbon-carbon double bond on the surface of the microsphere can react with the amine group of the laccase through aza-Michael addition,and the microsphere could be used as a carrier to immobilize the laccase.The optimal enzyme immobilization conditions were obtained through single factor analysis.2,2'-Diazo-bis-3-ethylbenzothiazolin-6-sulfonic acid was used as substrate to characterize the enzyme activity of the immobilized enzyme.When PEA microspheres were used to immobilize laccase,the highest immobilized amount was 29.92 mg/g,the optimal p H of immobilized enzyme activity is 5,the optimal use temperature of immobilized enzyme is40 °C,and the maximum activity is 3.89 U/mg.When PAS microspheres were used to immobilize laccase,the highest immobilization amount is 84.52 mg/g,the optimal p H for immobilized enzyme is 4,the optimal temperature for immobilized enzyme is 40 °C,and the maximum activity was 4.68 U/mg.The immobilized enzyme was used to catalyze the oxidative degradation of malachite green,and the highest degradation rate of the PEA immobilized enzyme for 4 h was 96%,and the enzyme activity remained 53% after repeated use for 4 times.The highest degradation rate of PAS immobilized enzyme degradation for 4 h was 97%,and the activity remained 66% after recycling 4 times.