Nucleation mechanism of α-cyclodextrin-enhanced crystallization of some semicrystalline aliphatic polymers
Nucleation mechanism of α-cyclodextrin-enhanced crystallization of some semicrystalline aliphatic polymers
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DOI：
10.1021/ma050826r
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发表时间：
2005-09-06
期刊：
影响因子：
5.5
通讯作者：
Inoue, Y
中科院分区：
文献类型：
--
作者：
Dong, T;He, Y;Inoue, Y
采用差示扫描量热法（DSC）和偏光显微镜研究了α -环糊精（α - cd）及其与聚e -己内酯（PCL）、聚乙二醇（PEG）和聚丁二酸丁二烯（PBS）包合物（ICs）对PCL、PEG和PBS结晶的成核影响。采用DSC、傅里叶变换红外光谱、广角x射线衍射（WAXD）和溶液H-1核磁共振（NMR）表征了a-CD与PCL、PEG和PBS的集成电路形成。WAXD研究表明，所有α - cd - ic均采用通道结构。DSC和H-1 NMR结果表明，聚合物链部分被α - cds络合。因此，当将α - cd - ic作为成核剂添加到聚合物中时，体相中的聚合物链不仅可以接触α - cd大环的外部，还可以接触从α - cd空腔中伸出的聚合物链的末端和/或α - cd露出的自由链段。因此，大块聚合物与成核剂之间界面相互作用的差异应该是成核效果差异的原因。- cd - pcl - ic粒子对块状PBS结晶的成核影响不大；然而，它们可以大大加速块体PCL的成核和结晶。在PBS和PEG的结晶过程中也观察到相同的结果；即PBS- ic和PEG- ic颗粒分别能极大地加速PBS和PEG的成核和结晶。可见，给定聚合物的集成电路可以极大地增强聚合物本身的成核和结晶。这一结果可能是由于聚合物片段的未覆盖部分受到其位于- cd腔的内部部分的限制，迁移有限，导致聚合物结晶成核。还考察了细滑石粉的作用。实验结果表明，cd对聚合物结晶的成核能力与滑石相当。
The nucleation effects of alpha-cyclodextrin (alpha-CD) and its inclusion complexes (ICs) with poly(E-caprolactone) (PCL), poly(ethylene glycol) (PEG), and poly(butylene succinate) (PBS) on the crystallization of PCL, PEG, and PBS were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy. The formations of ICs of a-CD with PCL, PEG, and PBS were characterized by DSC, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction (WAXD), and solution H-1 NMR. The WAXD studies showed that all of the alpha-CD-ICs adopt a channel structure. Both DSC and H-1 NMR results suggested that the polymer chains were partially complexed by alpha-CDs. Thus, the polymer chains in the bulk phase can contact not only the exterior of the alpha-CD macrocycle but also the end parts of polymer chains protruding from the alpha-CD cavity and/or the free chain segments uncovered by alpha-CD, when the alpha-CD-IC as a nucleating agent is added into the polymers. Therefore, the difference in the interfacial interaction between bulk polymers and the nucleating agents should be responsible for the difference in the nucleation effects. alpha-CD-PCL-IC particles have little nuclear formation effect on the crystallization of bulk PBS; however, they can greatly accelerate the nucleation and crystallization of the bulk PCL. The same results are also observed during the crystallization of PBS and PEG; that is, PBS-IC and PEG-IC particles can greatly accelerate the nucleation and crystallization of PBS and PEG, respectively. It seemed that IC of a given polymer could greatly enhance the nucleation and crystallization of the polymer itself. This result may be attributable to the limited mobility of the uncovered part of the polymer segments constrained by its interior part resided in the alpha-CD cavity, leading to the nucleation of polymer crystallization. The effect of fine talc powder was also examined. The experimental results suggested that the nucleation ability of alpha-CD on the crystallization of the polymer is comparable to that of the talc.