脂肪酶催化合成聚己内酯及其产物的降解

发布时间：2018-07-06 10:59

  本文选题：聚己内酯 + 酶　； 参考：《大连海事大学》2016年硕士论文

【摘要】：作为一种重要的生物可降解型的高分子材料,聚己内酯在生物、化工、医用材料领域得到了广泛的应用。传统的化学方法合成的产物通常会因为重金属的残留而表现出毒性,限制了聚己内酯的使用。本文从生物催化的角度出发,探究了利用生物酶进行聚己内酯的催化合成的合成体系,同时对生物催化合成的聚己内酯的产物的降解性能进行了初步的探讨。本论文利用几种能够催化聚酯聚合的生物酶进行了己内酯的开环聚合,通过实验结果的对比筛选,最终选定了南极假丝酵母脂肪酶B为己内酯开环聚合的催化剂,并利用其固定化形式Novozyme 435进行了生物酶催化己内酯开环聚合的最适反应体系的探究。利用红外线光谱分析仪(FTIR)、X射线衍射(XRD)、核磁氢谱分析(1HNMR)、示差扫描量热仪(DSC)、综合热分析仪(TGA)、凝胶渗透色谱(GPC)等手段,结合产物的转化率、分子量等变化,确定了酶催化聚合的催化剂的使用量、聚合反应的温度、反应时间、反应溶剂的选择以及探究了酶重复利用的催化能力。研究结果表明,催化剂的用量较大程度上影响产物的转化率,以10ml己内酯为反应原料的前提下,催化剂为0.50g的使用量可以得到相对较高转化率的产物；在生物酶的活性温度范围内确定了反应的最适温度为45℃；在上述确定的反应体系下,对反应时间进行了考察,结果表明,随着反应时间的增加,产物的分子量逐步上升,确定了24h为最适反应时间；还对反应的溶剂进行了探讨,发现疏水性溶剂更有利于该聚合反应进行的现象,最后对酶重复催化的性能进行了探讨,酶的催化性能呈现逐步降低的趋势,但随着催化次数的增多,其催化能力下降趋势逐渐趋向于平稳,表明了酶重复再利用的可行性。本文也对酶催化合成的聚己内酯降解性能的初步探讨,样品的失重率以及单位面积失重随着降解时间的增加而逐渐增加,无溶剂体系下Novozyme 435催化聚合的产物的降解速率快于甲苯溶剂下的产物。总体上,酶催化己内酯聚合的产物的降解性能由于传统的化学方法催化合成的聚己内酯
[Abstract]:As an important biodegradable polymer, polycaprolactone has been widely used in biological, chemical and medical materials. The products synthesized by traditional chemical methods are usually toxic because of heavy metal residues, limiting the use of polycaprolactone. From the point of view of biocatalysis, the synthesis system of polycaprolactone with biological enzyme was studied, and the degradation performance of polycaprolactone synthesized by biocatalysis was also discussed. In this paper, the ring-opening polymerization of caprolactone was carried out by using several biological enzymes that can catalyze the polymerization of polyester. Finally, the lipase B of Candida Antarctica was selected as the catalyst for the ring-opening polymerization of caprolactone. The optimum reaction system for the ring-opening polymerization of caprolactone catalyzed by biological enzyme was studied by using its immobilized form Novozyme 435. Infrared spectrometer (FTIR) X-ray diffraction (XRD), nuclear magnetic hydrogen spectroscopy (1HNMR), differential scanning calorimetry (DSC), comprehensive thermal analyzer (TGA), gel permeation chromatography (GPC) were used to combine the conversion and molecular weight of the products. The amount of catalyst used for enzymatic polymerization, the temperature of polymerization, the reaction time, the selection of reaction solvent and the catalytic ability of enzyme reuse were determined. The results showed that the amount of catalyst affected the conversion of the product to a large extent. Under the premise of using 10ml caprolactone as raw material, the product with higher conversion could be obtained when the amount of catalyst was 0.50g. The optimum reaction temperature was 45 鈩，

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