Preparation method of comb-like copolymer containing poly-hydroxycarboxylic acid
A technology of comb copolymer and hydroxycarboxylic acid, which is applied in the field of preparation of comb copolymer, and can solve the problems of high production cost and low thermal stability of the copolymer
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preparation example 1
[0049] After pouring 100 g of 90 wt % L-lactic acid aqueous solution into a 500 mL four-necked flask, the flask was placed in an oil bath. Install a stirrer on the four-neck flask, insert a thermocouple thermometer, connect the vacuum pipeline and the nitrogen pipeline and replace with nitrogen for 3 times, then raise the temperature of the oil bath to 120°C for dehydration. The system pressure gradually decreased from normal pressure to 5KPa within 60 minutes from the start of dehydration; then continued dehydration at 5KPa for 1.5 hours (a total of 2.5 hours of dehydration). Then the temperature of the system was raised to 190°C, the pressure was gradually reduced from normal pressure to 0.3KPa within 2 hours and the pressure was kept at 0.3KPa to obtain a polylactic acid prepolymer after melt polymerization for 28 hours (30 hours in total). By testing the product sample, the number average molecular weight Mn: 2000 was obtained.
preparation example 2
[0051] After pouring 100 g of 90 wt % L-lactic acid aqueous solution into a 500 mL four-necked flask, the flask was placed in an oil bath. Install a stirrer on the four-neck flask, insert a thermocouple thermometer, connect the vacuum pipeline and the nitrogen pipeline and replace with nitrogen for 3 times, then raise the temperature of the oil bath to 120°C for dehydration. The system pressure gradually decreased from normal pressure to 5KPa within 60 minutes from the start of dehydration; then continued dehydration at 5KPa for 1.5 hours (a total of 2.5 hours of dehydration); at this time, after returning the system pressure to normal pressure with nitrogen, add p-toluenesulfonic acid 306mg. Then the temperature of the system was raised to 160°C, the pressure was gradually reduced from normal pressure to 0.3KPa within 1 hour and the pressure was kept at 0.3KPa to obtain a polylactic acid prepolymer after melt polymerization for 0.5 hours (1.5 hours in total). By testing the ...
preparation example 3
[0053] After adding 90 g of L-lactic acid oligomers and 722 mg of methanesulfonic acid to a 500 mL four-necked flask, the flask was placed in an oil bath. Install a stirrer on the four-neck flask, insert a thermocouple thermometer, connect the vacuum pipeline and nitrogen pipeline and replace with nitrogen for 3 times, raise the temperature of the system to 170°C, and gradually reduce the pressure from normal pressure to 0.1KPa within 0.5 hours And keeping the pressure at 0.1KPa, the polylactic acid prepolymer was obtained after melt polymerization for 0.5 hours (1 hour in total). By testing the product sample, the number average molecular weight Mn: 460 was obtained.
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