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首页> 外文期刊>Journal of Applied Polymer Science >Synthesis and Enzymatic Degradation of High Molecular Weight Aliphatic Polyesters
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Synthesis and Enzymatic Degradation of High Molecular Weight Aliphatic Polyesters

机译：高分子量脂肪族聚酯的合成与酶促降解

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The aliphatic polyesters with high molecular weight have been prepared according to two methods. First is the synthesis of the polyesters by polycondensation of dimethyl succinate (DMS) with 1,4-butanediol (ED) using various metal alkoxides as a catalyst. Among the metal alkoxides used, titanium tetraisopropoxide [Ti(OiPr)J gave the best results (highest molecular weight and yield). Thus, we have prepared aliphatic poly- esters using a variety combinations of diesters [MeOOC-{CH2)x-COOMe, x= 2-8) with ED by the catalysis of Ti(OiPr)4. The polyesters with high number-average molecular weight (Mn > 35,000), except dimethyl adipate (DMA, x= 4)JBD polyester (Mn = 26,900), were obtained in high yield. The melting temperatures (T m) of polyesters were relatively low (43.4-66.8°C) except that (115.6°C) of the DMS/BD polyester. Second is the synthesis ofhigh molecular weight polyesters by chain extension reaction of lower molecular weight (Mn = 15,900--26,000) polyesters using hexamethylene diisocyanate (HDl) as a chain extender. The Mn values of chain-extended polyesters consequently increased more than two times (Mn = 34,700--56,000). The thermal properties of polyesters hardly changed before and after chain extension. Enzymatic degradations of the polyesters were performed using three different enzymes (cholesterol esterase, lipase E, and Rhizopus delemar lipase) before chain extension. The enzymatic degradability varied depending on both thermal properties of polyesters [melting temperature and heat of fusion (crystallinity?) and the substrate specificity of enzymes, but it was the following order: cholesterol esterase > lipase E > R. delemarlipase. The lH-NMR spectrum ofwater-soluble degraded products (If the polyester indicated that the polyester was degraded into a condensation product of diol with diester in a monomer form. The enzymatic degradation of chain extended poly- esters was slightly smaller than that before chain extension, but proceeded steadily.
机译：具有高分子量的脂族聚酯已经根据两种方法制备。首先是使用各种金属醇盐作为催化剂，通过琥珀酸二甲酯（DMS）与1,4-丁二醇（ED）的缩聚反应合成聚酯。在所用的金属醇盐中，四异丙氧基钛[Ti（OiPr）J]效果最佳（分子量和产率最高）。因此，我们通过Ti（OiPr）4的催化作用，使用二酯[MeOOC- {CH2）x-COOMe，x = 2-8）与ED的各种组合制备了脂肪族聚酯。以高收率获得数均分子量高（Mn> 35,000）的聚酯，但己二酸二甲酯（DMA，x = 4），JBD聚酯（Mn = 26,900）除外。聚酯的熔融温度（T m）相对较低（43.4-66.8°C），除了DMS / BD聚酯的熔融温度（115.6°C）。其次是使用六亚甲基二异氰酸酯（HD1）作为扩链剂，通过低分子量（Mn = 15,900--26,000）聚酯的扩链反应合成高分子量聚酯。因此，扩链聚酯的Mn值增加了两倍以上（Mn = 34,700--56,000）。在扩链前后，聚酯的热性能几乎不变。在链延长之前，使用三种不同的酶（胆固醇酯酶，脂肪酶E和根霉Delemar脂肪酶）进行聚酯的酶降解。酶的可降解性取决于聚酯的热性质[熔融温度和熔化热（结晶度？）以及酶的底物特异性，但顺序如下：胆固醇酯酶>脂肪酶E>脱脂脂肪酶。水溶性降解产物的1H-NMR谱图（如果聚酯表明聚酯已降解为单体形式的二元醇与二酯的缩合产物，则扩链聚酯的酶促降解比扩链前的酶促降解小，但进展稳定。

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