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首页> 外文期刊>Journal of Applied Polymer Science >Crystallization and melting behavior of poly(epsilon-caprolactone-co--valerolactone) and poly(epsilon-caprolactone-co-L-lactide) copolymers with novel chain microstructures
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Crystallization and melting behavior of poly(epsilon-caprolactone-co--valerolactone) and poly(epsilon-caprolactone-co-L-lactide) copolymers with novel chain microstructures

机译：具有新型链微结构的聚（ε-己内酯-共-戊内酯）和聚（ε-己内酯-共-L-丙交酯）共聚物的结晶和熔融行为

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Nuclear magnetic resonance spectroscopy (NMR) characterization of the statistical copolymers of this study showed that the poly(epsilon-caprolactone-co-L-lactide)s, with epsilon-caprolactone (epsilon-CL) molar contents ranging from 70 to 94% and epsilon-CL average sequence length (l(CL)) between 2.20-9.52, and the poly(epsilon-caprolactone-co--valerolactone)s, with 60 to 85% of epsilon-CL and l(CL) between 2.65-6.08, present semi-alternating (R2) and random (R approximate to 1) distribution of sequences, respectively. These syntheses were carried out with the aim of reducing the crystallinity of poly(epsilon-caprolactone) (PCL), needed to provide mechanical strength to the material but also responsible for its slow degradation rate. However, this was not achieved in the case of the epsilon-caprolactone-co--valerolactone (epsilon-CL-co--VAL). Non-isothermal cooling treatments at different rates and isothermal crystallizations (at 5, 10, 21 and 37 degrees C) were conducted by differential scanning calorimetry (DSC), and demonstrated that epsilon-CL copolymers containing -valerolactone (-VAL) exhibited a larger crystallization capability than those of L-lactide (L-LA) and also arranged into crystalline structures over shorter times. The crystallization enthalpies of the epsilon-CL-co--VAL copolymers during the cooling treatments and their heat of fusion (H-m) at the different isothermal temperatures were very large (i.e. H-c>53 Jg(-1)) and in some cases, unrelated to the copolymer composition. In some compositions, such as the 60 : 40, Wide Angle X-ray Scattering (WAXS) proved that that these two lactones undergo isomorphism and co-crystallize in a single cell. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42534.
机译：这项研究的统计共聚物的核磁共振波谱（NMR）表征表明，聚（ε-己内酯-co-L-丙交酯）的摩尔含量为70％至94％， epsilon-CL的平均序列长度（l（CL））在2.20-9.52之间，以及聚（epsilon-己内酯-共-戊内酯），其中60％至85％的epsilon-CL和l（CL）在2.65-6.08之间分别代表序列的半交替（R2）和随机（R近似于1）分布。进行这些合成的目的是降低聚（ε-己内酯）（PCL）的结晶度，这是为材料提供机械强度所必需的，但也要负责其缓慢的降解速率。然而，在ε-己内酯-共-戊内酯（ε-CL-co-VAL）的情况下，这没有实现。通过差示扫描量热法（DSC）进行了不同速率和等温结晶化（分别在5、10、21和37摄氏度下）的非等温冷却处理，结果表明，含有-戊内酯（-VAL）的ε-CL共聚物表现出较大的具有比L-丙交酯（L-LA）更高的结晶能力，并且还可以在较短的时间内排列成晶体结构。 ε-CL-co-VAL共聚物在冷却过程中的结晶焓及其在不同等温温度下的熔化热（Hm）非常大（即Hc> 53 Jg（-1）），在某些情况下，与共聚物组成无关。在某些成分（例如60:40）中，广角X射线散射（WAXS）证明这两个内酯在同一个细胞中经历同构并共结晶。 （c）2015 Wiley Periodicals，Inc. J. Appl。 Polym。科学2015，132，42534。

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