mPEG-b-PCL的酶催化反应挤出制备及其结构研究

以小型双螺杆挤出机为反应容器,以脂肪酶Novozyme-435为催化剂,采用反应挤出工艺,研究了甲氧基聚乙二醇(mPEG)引发ε-己内酯的开环聚合反应,制得甲氧基聚乙二醇-b-聚ε-己内酯(mPEG-b-PCL),考察了ε-己内酯单体转化率(η),mPEG的引发效率(ηmPEG),水对聚合反应的影响。结果表明:由核磁共振氢谱分析确定聚合产物为mPEG-b-PCL;在反应温度90℃条件下,反应时间为120,240,360min时,η分别为82.01%,89.76%,92.61%,ηmPEG分别为28.17%,40.13%,35.31%,即ηmPEG先增加后降低;PCL链段的水解是ηmPEG降低的主要原因。

Preparation and structure of mPEG-b-PCL by enzymatic reaction extrusion

Using a small twin-screw extruder as the reaction vessel,the ring-opening polymerization ofε-caprolactone initiated by methoxy polyethylene glycol(mPEG)into methoxy poly(ethylene glycol)-b-poly(ε-caprolactone)(mPEG-b-PCL)was studied by enzyme-catalyzed reaction extrusion process using lipase Novozyme-435 as catalyst.The conversion ofε-caprolactone monomer(η),the initiation efficiency of mPEG(ηmPEG)and the effect of water on the polymerization reaction were investigated.The results showed that the polymerization product was determined as mPEG-b-PCL by nuclear magnetic resonance spectroscopy;ηwas 82.01%,89.76%,and 92.61%andηmPEG was 28.17%,40.13%and 35.31%at 90℃,showing an upward and then downward tendency,when the reaction time was 120,240 and 360 min,respectively;and the hydrolysis of PCL segment was the main reason for the decrease ofηmPEG.