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Synthesis of high-molecular-weight polylactic acid by co-use method of self-catalytic melt polycondensation of lactic acid and creatinine-catalyzed solid-phase polycondensation

A melt polycondensation, high molecular weight technology, applied in the field of solid phase polycondensation into high molecular weight polylactic acid, can solve problems such as inability to remove tin salt catalysts, potential safety hazards, avoid product racemization, avoid agglomeration, and improve the reaction rate. Effect

Active Publication Date: 2012-09-19
无锡南大绿色环境友好材料技术研究院有限公司
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Problems solved by technology

Although these two methods can synthesize high-molecular-weight polymers, the tin salt catalyst used after the polymerization cannot be completely removed from the polymer.
The research work of many scholars at home and abroad has proved that metal tin compounds are cytotoxic, so there are certain safety hazards in the use of tin salts to catalyze the synthesis of polylactic acid in the field of human medicine

Method used

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  • Synthesis of high-molecular-weight polylactic acid by co-use method of self-catalytic melt polycondensation of lactic acid and creatinine-catalyzed solid-phase polycondensation
  • Synthesis of high-molecular-weight polylactic acid by co-use method of self-catalytic melt polycondensation of lactic acid and creatinine-catalyzed solid-phase polycondensation
  • Synthesis of high-molecular-weight polylactic acid by co-use method of self-catalytic melt polycondensation of lactic acid and creatinine-catalyzed solid-phase polycondensation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035]1) Add 200 mL of L-lactic acid aqueous solution with a mass fraction of 90% and an optical purity of 99.5% into the reactor without adding any catalyst, replace the air in the reactor with inert gas three times, and heat to 160°C under normal pressure and inert gas atmosphere Dehydration 6h;

[0036] Then the vacuum degree of the reactor was increased to 100torr, and the reaction was continued at 160°C for 6h;

[0037] Then increase the vacuum degree of the reactor to 30torr, and continue the reaction at 160°C for 6h;

[0038] Finally, the reactor was decompressed to 10torr, and the temperature was raised to 200°C for 30h to obtain M w 1.3×10 4 LMW-PLLA;

[0039] 2) The weight average molecular weight M w 1.3×10 4 100g of LMW-PLLA, add 5mg of creatinine (the amount is 0.005% of the mass of LMW-PLLA) in molten state and under the protection of inert gas, cool and grind to obtain 60-70 mesh powder;

[0040] Add LMW-PLLA powder to figure 1 The shown fixed-bed vacuum-...

Embodiment 2

[0044] 1) Add 150 mL of L-lactic acid aqueous solution with a mass fraction of 90% and an optical purity of 99.5% into the reactor without adding any catalyst, replace the air in the reactor with inert gas three times, and heat to 140°C under normal pressure and inert gas atmosphere Dehydration 3h;

[0045] Then the vacuum degree of the reactor was increased to 100torr, and the reaction was continued at 140°C for 3h;

[0046] Then increase the vacuum degree of the reactor to 30torr, and continue the reaction at 140°C for 3h;

[0047] Finally, the reactor was decompressed to 10torr, and the temperature was raised to 170°C for 25h to obtain M w 1.0×10 4 LMW-PLLA;

[0048] 2) the M w 1.0×10 4 Add 80g of LMW-PLLA in molten state and under the protection of inert gas, add 40mg of creatinine (the amount is 0.05% of the mass of LMW-PLLA), cool and grind to get 60-70 mesh powder.

[0049] Add LMW-PLLA powder to figure 1 The shown fixed-bed vacuum-inert gas combined reactor. Pa...

Embodiment 3

[0053] 1) Add 100 mL of L-lactic acid aqueous solution with a mass fraction of 90% and an optical purity of 99.5% in the reactor, without adding any catalyst, replace the air in the reactor with inert gas three times, and heat to 130°C under normal pressure and inert gas atmosphere Dehydration 1h;

[0054] Then the vacuum degree of the reactor was increased to 100torr, and the reaction was continued at 130°C for 1h;

[0055] Then increase the vacuum degree of the reactor to 30torr, and continue the reaction at 130°C for 1h;

[0056] Finally, the reactor was depressurized to 10torr, and the temperature was raised to 160°C for 20h to obtain M w 0.8×10 4 LMW-PLLA;

[0057] 2) the M w 0.8×10 4 Add 50g of LMW-PLLA in molten state and under the protection of inert gas, add 250mg of creatinine (the amount is 0.5% of the mass of LMW-PLLA), cool and grind to get 60-70 mesh powder.

[0058] Add LMW-PLLA powder to figure 1 The shown fixed bed vacuum-inert gas combined reactor. Pa...

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Abstract

According to the invention, high-molecular-weight poly L-lactic acid is synthesized by the co-use method of self-catalytic melt polycondensation of L-lactic acid and creatinine-catalyzed solid-phase polycondensation of low-molecular-weight poly L-lactic acid (LMW-PLLA, Mw is 0.8x10<4> to 1.3x10<4>). According to the invention, low-molecular-weight poly L-lactic acid (LMW-PLLA) with the weight average molecular weight (Mw) from 0.8x10<4> to 1.3x10<4> is firstly synthesized by means of self-catalytic melt polycondensation of L-lactic acid under preferable conditions; and then, by using creatinine as a catalyst, solid-phase polycondensation is carried out in a fixed bed vacuum-inert gas co-use type solid-phase polycondensation reactor in combination with the operation methods for program-controlled heating and for staged increase of vacuum degree so as to synthesize poly L-lactic acid (PLLA) with high molecular weight (Mw is from 3.0x10<4> to 15.0x10<4>) and high isotacticity (more than 95%). The poly L-lactic acid product synthesized by the method disclosed by the invention has the characteristics that: no metal and other toxic ingredient are contained; the distribution of molecularweight is narrow (PDI (Polydispersity Index) is less than 2.3); the isotacticity is high (more than 95%); the color is good (snowy white); the Mw of polymer can be regulated as required within a range from 3.0x10<4> to 15.0x10<4>; the process for solid-phase polycondensation is a full-green process (no solvent is used and the three wastes are not generated); and the process is simple and convenient, and easy for industrial implementation.

Description

technical field [0001] The invention belongs to the technical field of biodegradable materials, and relates to a process method for synthesizing high-molecular-weight polylactic acid through solid-state condensation polymerization using biomass creatinine as a catalyst and low-molecular-weight polylactic acid as a raw material. Background technique [0002] Polylactic acid is a biodegradable material that can be completely degraded into carbon dioxide and water under a certain biochemical environment. Polylactic acid has good biocompatibility, can be completely absorbed by the human body, and has no toxic side effects. In recent years, with the rapid development of medicine and biomedical science, the demand for medical biodegradable materials with excellent biocompatibility and biosafety is increasing rapidly at home and abroad. Biodegradable polylactic acid has achieved many important applications in pharmaceutical science and biomedical engineering, such as: used as a ca...

Claims

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Application Information

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IPC IPC(8): C08G63/06C08G63/80C08G63/87
Inventor 李弘张全兴黄伟齐运彪江伟潘丙才
Owner 无锡南大绿色环境友好材料技术研究院有限公司
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