Direct identification of three crystalline phases in PEO-b-PCL-b-PLLA triblock terpolymer by In situ hot-stage atomic force microscopy
Direct identification of three crystalline phases in PEO-b-PCL-b-PLLA triblock terpolymer by In situ hot-stage atomic force microscopy
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原位热台原子力显微镜直接鉴定 PEO-b-PCL-b-PLLA 三嵌段三元共聚物中的三个结晶相
DOI：
10.1016/j.polymer.2020.122863
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发表时间：
2020-08
期刊：
影响因子：
4.6
通讯作者：
ro J.
中科院分区：
文献类型：
--
作者：
Palacios Jordana K.;Zhang Heng;Zhang Bin;Hadjichristidis Nikos;Muller Alej;ro J.
在这项工作中，我们提供了一个详细的描述的三层纳米级形态的三重结晶PEO-b-PCL-b-PLLA三嵌段共聚物通过热台原子力显微镜（AFM）成像和广角X射线散射（WAXS）分析首次获得。前体PCL-b-PLLA二嵌段共聚物也被包括在研究中用于比较目的。一个两步结晶协议已被应用到创建一个独特的层状形态。WAXS和AFM都揭示了二嵌段共聚物的双结晶性质。然而，在室温下通过AFM和WAXS识别三嵌段共聚物中的多个晶相并不简单。热台原子力显微镜的优势允许跟踪片状形态的演变以及三晶PEO-b-PCL-b-PLLA样品在加热过程中的连续熔化。考虑到每个结晶块的熔融温度，清楚地确定了现有的层状群体。在45 °C下，由于PEO晶体的熔化，最薄的薄片消失。当PCL晶体熔化时，中等尺寸的薄片在60 °C下消失。在该温度下，唯一剩余的晶体是PLLA块的晶体。AFM的机械模量图像和横截面高度的分析提供了进一步的证据的层状自组装的三嵌段共聚物。发现在室温下两种层状排列是可能的;或者是PCL和PEO层夹在PLLA层之间的完美交错（即，PLLA/PEO/PCL/PLLA），或者在随机分布的两个PLLA层状晶体之间仅有一个PEO或PCL层状晶体（即，PLLA/PEO/PLLA或PLLA/PCL/PLLA）。热台原子力显微镜是一种有价值的技术，以阐明复杂的形态特征的多晶系统。
In this work, we provide a detailed description of the tri-lamellar nanoscale morphology of a triple crystalline PEO-b-PCL-b-PLLA triblock terpolymer obtained by Hot-Stage Atomic Force microscopy (AFM) imaging and Wide Angle X-ray scattering (WAXS) analysis for the first time. The precursor PCL-b-PLLA diblock copolymer has also been included in the study for comparison purposes. A two-step crystallization protocol has been applied to create a distinct lamellar morphology. Both WAXS and AFM revealed the double crystalline nature of the diblock copolymer. However, the identification of multiple crystalline phases in the triblock terpolymer by AFM and WAXS at room temperature is not straightforward. The advantages of hot-stage AFM allowed following the evolution of the lamellar morphology and the successive melting of the tricrystalline PEO-b-PCL-b-PLLA sample during heating. Taking into account the melting temperature of each crystalline block, the existing lamellar populations were clearly identified. At 45 °C, the thinnest lamellae disappeared, due to the melting of PEO crystals. The medium size lamellae disappeared at 60 °C when PCL crystals melt. At that temperature, the only remaining crystals are those of the PLLA block. AFM mechanical modulus images and the analysis of the cross-sectional heights provide further evidence of the lamellar self-assembly of the triblock terpolymer. It was found that two lamellar arrangements are possible at room temperature; either a perfect interdigitation where PCL and PEO lamellae are sandwhiched between PLLA lamellae (i.e., PLLA/PEO/PCL/PLLA), or only one PEO or PCL lamella in between two PLLA lamellar crystals distributed randomly (i.e., PLLA/PEO/PLLA or PLLA/PCL/PLLA). Hot-Stage AFM is a valuable technique to elucidate the complex morphological features of multi-crystalline systems.
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影响因子：
4.6
作者：
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通讯作者：
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影响因子：
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作者：
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