聚乳酸—乙醇酸（PLGA）的合成工艺及结构性能研究
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摘要
以L-乳酸(L-LA)和乙醇酸(GA)(摩尔比20∶80)为原料,在170℃、系统压力小于70Pa下反应10h,直接熔融聚合合成乳酸-乙醇酸共聚物(PLGA),研究了催化剂种类﹑催化剂用量﹑复配催化剂比例以及抗氧剂用量对乳酸乙醇酸共聚物的特性粘数和产物色相的影响。结果表明,催化条件SnCl_2/PLGA=0.4w%,SnCl2/TSA=1∶1时,产物的特性粘数较高,为0.352dL/g,但产物的颜色较深,加入适量的抗氧剂1010后,产物色泽得到明显改善,但特性粘数较加入前有所降低。用IR和NMR手段表征产物结构,证明二者聚合后为共聚物,并非各自的均聚物,且共聚产物中乙醇酸比例大于投料值;用DSC和X-射线衍射分析其热性能及其结晶性,结果表明PLGA(20∶80)为非结晶高聚物。
以L-乳酸和乙醇酸直接熔融聚合得到乳酸乙醇酸预聚物(PLGA)为原料,进行固相聚合,适宜条件为:将预聚物在一定温度经两小时结晶热处理,氮气保护,在110℃固相反应30小时,可得特性粘数为聚合前1.84倍的产物。DSC分析结果表明,在一定温度下,产物熔点会随着反应时间的增加而相应增加,当反应时间过长超过30小时时,熔点反之会下降。
以熔融聚合所得预聚物PLGA为原料,2,4-甲苯二异氰酸酯(TDI)为扩链剂,进行熔融扩链,扩链时间60min、温度160℃、NCO/OH=1∶1时,可得特性粘数为扩链前2.65倍的聚合物。IR、DSC和X-射线衍射分析结果表明扩链后产物引人了-NH和苯环,产物的Tg较扩链前有所提高,但仍为非结晶高聚物。
Poly(lactic acid-glycolic acid)(PLGA) was synthesized through direct melt copolycondensation for 10h at 170℃and absolute pressure of 70Pa with L-lactic acid(LA) and glycolic acid(GA)(molar ratio of 20 to 80)as raw materials. The effect of kind of catalyst、quantity of catalyst and the ratio of composite catalyst on the [η] and color of the product was investigated, the results showed that the catalytic conditions SnCl_2/PLGA=0.4w%,SnCl2/TSA=1∶1, a product of high viscosity(0.352dL/g) was obtained with deeper color,and the color of the product was improved by adding appropriate amount of antioxidant 1010, but the viscosity lower than the pre-accession.The structure of PLGA was characterized by IR and NMR, the results proved that the product is a copolymer, but not their homopolymer, and the ratio of glycolic acid in the copolymer is greater than in the materials; By DSC and X-ray diffraction analysis of its thermal properties and its crystalline, the results showed that the PLGA (20∶80) is a non-crystalline polymers.
The solid-phase polycondensation of PLGA prepolymer was carried out and the appropriate conditions was obtained. Heat treatment time of the prepolymer is 2 hours and solid-state reaction temperature is 110℃in the protection of nitrogen for 30 hours. The [η] of PLGA was increased to 1.84 times. DSC analysis showed that under certain temperature, the melting point of the product was increased with increasing reaction time, but the melting point will decrease when the reaction time was more than 30 hours.
The chain extension of PLGA was carried out in melt state with 2,4-toluene diisocyanate (TDI) as chain extension agent. The [η] of PLGA was increased to 2.65 times in the proper condition (NCO/OH=1∶1 mol ratio; time: 60min; temperature:160℃). The results of IR、DSC and X-Ray investigations showed that through chain-extension reaction, the TDI was introduced in PLGA chain and the Tg was moderately increased. However, the polymer is still non-crystalline.
以L-乳酸和乙醇酸直接熔融聚合得到乳酸乙醇酸预聚物(PLGA)为原料,进行固相聚合,适宜条件为:将预聚物在一定温度经两小时结晶热处理,氮气保护,在110℃固相反应30小时,可得特性粘数为聚合前1.84倍的产物。DSC分析结果表明,在一定温度下,产物熔点会随着反应时间的增加而相应增加,当反应时间过长超过30小时时,熔点反之会下降。
以熔融聚合所得预聚物PLGA为原料,2,4-甲苯二异氰酸酯(TDI)为扩链剂,进行熔融扩链,扩链时间60min、温度160℃、NCO/OH=1∶1时,可得特性粘数为扩链前2.65倍的聚合物。IR、DSC和X-射线衍射分析结果表明扩链后产物引人了-NH和苯环,产物的Tg较扩链前有所提高,但仍为非结晶高聚物。
Poly(lactic acid-glycolic acid)(PLGA) was synthesized through direct melt copolycondensation for 10h at 170℃and absolute pressure of 70Pa with L-lactic acid(LA) and glycolic acid(GA)(molar ratio of 20 to 80)as raw materials. The effect of kind of catalyst、quantity of catalyst and the ratio of composite catalyst on the [η] and color of the product was investigated, the results showed that the catalytic conditions SnCl_2/PLGA=0.4w%,SnCl2/TSA=1∶1, a product of high viscosity(0.352dL/g) was obtained with deeper color,and the color of the product was improved by adding appropriate amount of antioxidant 1010, but the viscosity lower than the pre-accession.The structure of PLGA was characterized by IR and NMR, the results proved that the product is a copolymer, but not their homopolymer, and the ratio of glycolic acid in the copolymer is greater than in the materials; By DSC and X-ray diffraction analysis of its thermal properties and its crystalline, the results showed that the PLGA (20∶80) is a non-crystalline polymers.
The solid-phase polycondensation of PLGA prepolymer was carried out and the appropriate conditions was obtained. Heat treatment time of the prepolymer is 2 hours and solid-state reaction temperature is 110℃in the protection of nitrogen for 30 hours. The [η] of PLGA was increased to 1.84 times. DSC analysis showed that under certain temperature, the melting point of the product was increased with increasing reaction time, but the melting point will decrease when the reaction time was more than 30 hours.
The chain extension of PLGA was carried out in melt state with 2,4-toluene diisocyanate (TDI) as chain extension agent. The [η] of PLGA was increased to 2.65 times in the proper condition (NCO/OH=1∶1 mol ratio; time: 60min; temperature:160℃). The results of IR、DSC and X-Ray investigations showed that through chain-extension reaction, the TDI was introduced in PLGA chain and the Tg was moderately increased. However, the polymer is still non-crystalline.
引文
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