Green preparation of polycarbonate with melt transesterification method and its antibacterial modification
In order to reduce the environmental hazards during the synthesis of polycarbonate(PC)by phosgene gas method,and to solve the problem that the PC synthesized by melt transesterification has low molecular weight,diphenyl carbonate and bisphenol A were used as raw materials and the molecular weight of PC was increased through the control of polymerization process.Moreover,in order to enhance the antibacterial effect of PC as well as improve the heat resistance of the antibacterial agent,quaternary phosphonium salts modified by perfluoroalkyl chains with different fluorocarbon chain lengths were synthesized,and PC antibacterial films were prepared by hot-pressing molding.Taking the molecular weight of PC as the target,the polymerization process of PC was optimized,the structure of PC and antibacterial agents were characterized and the thermal stability of the antibac-terial agents were tested,the light transmittance and antibacterial properties of the PC antibacterial films were studied.The results show that the optimal process for synthesizing PC is 10 min of transesterification time,40 min of polycondensation at 250℃,which can lead to PC with a number average molecular weight of more than 12 000.The antibacterial quaternary hexafluorohexyl phospho-nium salt has good thermal stability,and it can be blended with PC for preparing antibacterial films with the highest transmittance of 89%by the hot-pressing method.And the PC film containing 4 phr quaternary hexafluorohexyl phosphonium salt has the optimal antibacterial effect,with antibacterial rate of 95%against Staphylococcus aureus and 94%against Escherichia coli.The synthesis of antibacterial PC film is green and environmentally friendly with excellent antibacterial performance,providing a safer solution for food packaging.
polycarbonatemelt transesterificationantibacterial agentantibacterial propertyfluorine alkyl phosphine salt
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