Preparation method for polylactic acid
A technology of polylactic acid and polymer, which is applied in the field of preparation of polylactic acid, can solve the problems that the product is not suitable for medical use and the catalyst is highly toxic, and achieve the effects of controllable molecular weight range, good optical purity, and mild reaction conditions
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Embodiment 1
[0033] Put 20g of L-lactide with an optical purity greater than 99% into the reactor, and then add 0.0038g of dibutylmagnesium and 0.207g of lauryl alcohol according to monomer:catalyst:initiator=5000:1:40 (molar ratio) . The reaction kettle was evacuated, and then replaced with nitrogen to repeat the operation three times. The reaction kettle was closed under vacuum, and then the reaction kettle was slowly heated and reacted at a constant temperature of 110°C for 48 hours. After stopping the reaction, the reaction kettle was cooled to room temperature, and dichloromethane was added to wash the unreacted monomer in the kettle. Finally, the polymer is placed in a vacuum drying oven and vacuum dried at 30°C for 48 hours to obtain a white translucent solid with a yield of 95% and an optical purity of greater than 99%. The polymer viscosity is about 0.8dl / g (ASTM D2857-95).
Embodiment 2
[0035] Put 20g of L-lactide with an optical purity greater than 99% into the reactor, and then add 0.0038g of dibutylmagnesium and 0.0309g of lauryl alcohol according to monomer:catalyst:initiator=5000:1:6 (molar ratio) . The reaction kettle was evacuated, and then replaced with nitrogen to repeat the operation three times. The reaction kettle was closed under vacuum, and then the reaction kettle was slowly heated and reacted at a constant temperature of 130°C for 48 hours. After stopping the reaction, the reaction kettle was cooled to room temperature, and chloroform was added to wash the unreacted monomer in the kettle. Finally, the polymer was placed in a vacuum drying oven and vacuum dried at 30°C for 48 hours to obtain a white solid with a yield of 92% and an optical purity of greater than 99%. The polymer viscosity is 3.2 dl / g (ASTM D2857-95).
Embodiment 3
[0037] Put 20 g of lactide into the reactor, and then add 0.0038 g of dibutyl magnesium and 0.0103 g of lauryl alcohol according to monomer:catalyst:initiator=5000:1:2 (molar ratio). The reactor was evacuated, and then replaced with nitrogen to repeat the operation three times. The reactor was closed under vacuum, and then the reactor was slowly heated and reacted at a constant temperature of 120°C for 48 hours. After the reaction was stopped, the reaction kettle was cooled to room temperature, and then dichloromethane was added to wash the unreacted monomer in the kettle. Finally, the polymer was placed in a vacuum drying oven and vacuum dried at 30° C. for 48 hours to obtain a pale yellow solid with a yield of 92% and a polymer viscosity of 5.0 dl / g (ASTMD2857-95).
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