Ring-opening Polymerization And Characterization Of ?-caprolactone And L-lactide Using Calcined Kaolin Catalyst

PCLA(copolymer of ?-caprolactone and L-lactide)is a biodegradable material,which own excellent biocompantibility,biodegradability and mechanical properties.It has applied in many different fields.Preparation of PCLA should be initiated by catalyst and used melting polymerization method.At present,the catalysts for preparation of PCLA are almost organic metal catalysts(for example:Sn(Oct)2),which have low biological toxicity,which will decrease the biocompatibility of the PCLA,low molecular weigh and wide distribution,to a certain extent,limiting the range of applition and value in use of PCLA.Therefore the developing a safe,efficient catalyst for preparing PCLA will become the key research direction from now on.Kaolin is ubiquitous mineral material,which have good compatibility,less environmental side effects.Effective components of it is Al2O3·2SiO2·2H20.After calcination at a certain temperature,the material physical structure will change and decrease the aluminum coordination number,showing certain catalytic activity.Therefore,this paper uses the properties of calcined kaolin to catalyze the synthesis of PCLA.First of all,study optimum mole ratio of the two reaction monomer.The results showed,the best mole ratio of ?-caprolactone and L-lactide was 82:18,with high productivity polymerization yield and high molecular weight in different dosage of catalyst,reaction time and temperature conditions.Secondly,study of catalyst dosage,reaction temperature,reaction time on the polymerization effect.(1)In different reaction temperation and time,we studied catalyst dosage between 0.0001g and 0.01g,the result showed that catalyst dosage was 0.005g,yield of polymer was high.Catalyst dosage more 0.005g or less 0.005g,yield of reaction decreased,indicating that existing significant activity value.(2)In different reaction time,catalyst for 0.005g,we studied reaction temperature from 120 ? to 160 ?.The result showed that while reaction temperature is 140?,yield and molecular weight were high and the molecular weight distribution of PLLA maintained about 1.5 and below,indicating that the effect of polymerization temperature on polymerization existed a best value.(3)Under the conditions of the catalyst dosage of 0.005g,reaction temperation of 140?,we studied reaction time from 18h to 72h,the productivity of products increased with the prolonging polymerization time,however,once the time overtook a certion value,the productivity declined.When reaction time was 48h,yield and molecular weigh were high.According to the results of the experiment showed that this topic adopting calcined kaolin completely instead of the traditional Sn(Oct)2 catalized s-caprolactone and L-lactide ring-opening polymerization successfully.This method is more secure,concise,catalytic efficiency.It was a breakthrough of research on viridis chemistry.