Metakaolin For Catalytic Preparation Of Poly(?-caprolactone) And Graphene Oxide For Modified Preparation Of Poly(Lactic Acid)

Because of good biocompatible and biodegradable properties,poly(s-caprolactone)(PCL)and poly(lactide acid)(PLA)have been drawn great attention,often acting as good biomedical materials and biodegradable materials.It can be degraded absolutely in vivo in two years and metabolized into carbon dioxide and water.Kaolin is a kind of natural mineral materials.In recent years,with its low cost and wide source,kaolin have been widely used in ceramics,drug slow-releasing fields and so an.Kaolin calcinated in high temperature loses the hydroxy groups and the content of silica,aluminium trioxide increase.These make the metakaolin a new type of nano catalyst for increase of the reactivity points.Today,metakaolin is often embedded,used as the filling of functional polymeric material.This paper mainly discusses the synthesis and properties of PCL,the development process of its application and chain extension of PLA.PCL and GO/PLA of high molecular weight was successfully produced through the ring-opening polymerization of?-caprolactone which catalyzed by the new type of mineral material metakaolin.The microstructure and thermal properties of PCL have been characterized by FT-IR,1H-NMR,DSC and XRD respectively.In these experiments,metakaolin was used as the catalyst of the ring opening polymerization of ?-caprolactone.The effect of the reaction time and temperature,catalyst amount on the molecular weight and yield of PCL has been investigated.Using the method of bulk polymerization,PCL was synthesized under the conditions of different mass ratio of monomer to catalyst,reaction temperature and reaction time.Combined with the yield of the PCL,number average molecular weight under different conditions,we discussed the optimum condition for synthesis of PCL.Through the experiment,it is concluded that when the reaction temperature is 140?,the reaction time is 30h and the mass ratio of monomer to metakaolin is 1000:1,the yield of PCL can reach as high as 90.51%,the molecular weight of which can reach up to 78619?Then graphite oxide was prepared,and then was subjected to ultrasonic treatment in distilled water to prepare graphene oxide.Graphene oxide modified PLA was synthesized by Steglich esterification and characterized by IR,XRD,DSC and GPC.The analysis results show that GO/PLA was successfully prepared.Finally,levofloxacin was chosen as the model drug,GO/PLA was used as drug carrier material for preparing tablets.