多臂活性聚乳酸预聚物的制备及固化交联行为

Preparation and Cross-Linking Behavior of Active Prepolymer of Multiarm-Poly(Lactic Acid)

以L-乳酸为原料,分别以乙二醇、丙三醇、季戊四醇为支化剂,通过熔融缩聚的方法制备了端務基聚乳酸(0HPLA).采用丙烯酸对OHPLA进行端基改性,制备了端双键活性聚乳酸(DPLA),进一步固化交联生成交联结构聚乳酸(CPLA)。采用红外光谱、核磁共振、凝胶渗透色谱、差示扫描量热及热重分析对OHPLA、DPLA、CPLA的结构、分子量、凝胶含量及热性能进行了表征。结果表明:OHPLA臂数越多,DPLA反应活性点越多,CPLA交联程度越高,凝胶含量越高;DPLA分子量越高,链段的移动能力下降,交联反应活性下降,越不利于形成交联结构;当4sDPLA分子量为4369g/mol时,具有较好的热稳定性,热失重率为10%与50%时的热分解温度分别为247和356℃,凝胶含量达到88.52%。

Hydroxyl-terniinated poly(lactic acid)(OHPLA) was synthesized from L-lactide by means of the direct melt polycondensation, using ethylene glycol, propanetriol, pentaerythritol as the branched agent. The end group of OHPLA was modified by acrylic acid to active terminal double bond poly (lactic acid)(DPLA) which was further crosslinked to crosslinked poly (lactic acid)(CPLA). The structure, molecular weight, gel content and thermal properties of OHPLA , DPLA and CPLA were investigated via FTIR, 1HNMR, GPC, DSC and TGA. The results showed that the degree of cross-linking and gel content of CPLA increased with the number of OHPLA arms and the reactive point of DPLA. The crosslinked structure of CPLA was not easily formed with increasing molecular weight and decreasing chain mobility of DPLA. 4sCPLA prepared from 4sDPLA with a molecular weight of 4 396 g/mol had a high degree of cross-linking and a gel content of 88. 52%, resulting in the good thermal stability. The thermal decomposition temperature corresponding to the thermal weight loss rate of 10% and 50% were 247 and 356℃,respectively.