Formation, Characterization, and Segmental Mobilities of Block Copolymers in Their Urea Inclusion Compound Crystals
Formation, Characterization, and Segmental Mobilities of Block Copolymers in Their Urea Inclusion Compound Crystals
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DOI：
10.1021/ma970213h
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发表时间：
1997-05
期刊：
影响因子：
5.5
通讯作者：
N. Vasanthan;I. D. Shin;Lei Huang;S. Nojima;A. Tonelli
中科院分区：
文献类型：
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作者：
N. Vasanthan;I. D. Shin;Lei Huang;S. Nojima;A. Tonelli
我们报道了在小分子宿主尿素(U)和两个嵌段共聚物客体之间形成结晶包合化合物（ic）：(i)聚e-己内酯-聚丁二烯（PCL-PBD）和（ii） pcl -聚环氧乙烷-PCL （PCL-PEO-PCL）。两种嵌段共聚物- u - ic均由尿素饱和溶液共结晶而成，用DSC、x射线衍射、13c NMR和FTIR光谱对两种嵌段共聚物- u - ic进行了观察。发现PCL- pbd二嵌段共聚物的两个嵌段都包含在U-IC通道中，而PCL- peo -PCL三嵌段共聚物的末端PCL嵌段只包含在U-IC通道中。PCL-PBD-U-IC的结构似乎是传统六边形结构和PCL块周围约5.5 a狭窄通道的组合，而PBD块包含在先前在PEO（低聚物）-U-IC和聚丙烯-U-IC中观察到的扩展的四方结构中，其中尿素基质通道直径被认为扩展到7a以上。这可能解释了PBD块是如何在U-IC通道中容纳的，PBD块包含12%的1,2单元，具有庞大的-CH= ch2侧链。同样，在PCL- peo -PCL- u -IC中，仅包括终端PCL块，IC结构看起来与通常的窄通道，六角形结构非常相似，例如，在PCL- u -IC中，PCL均聚物和尿素之间的IC。因此，我们可以在两种不同的U-IC环境中观察到PCL嵌段，并可以将它们的行为与均聚物PCL-U-IC和均聚物和嵌段共聚物体晶体中的PCL链进行比较。此外，T lΡ对H自旋扩散的测量揭示了嵌段共聚物-U-IC的结构方面，并且U-IC包含的聚合物链与它们的邻居的隔离可能允许通过观察这些嵌段共聚物-U-IC中的t1 ρ(1 H)弛豫来探测一维H自旋扩散。
We report the formation of crystalline inclusion compounds (ICs) between the small-molecule host urea (U) and two block copolymer guests: (i) poly(e-caprolactone)-polybutadiene (PCL-PBD) and (ii) PCL-poly(ethylene oxide)-PCL (PCL-PEO-PCL). Both block copolymer-U-ICs are formed by cocrystallization from saturated solutions of urea, and each block copolymer-U-IC was observed with DSC, X-ray diffraction, and 13 C NMR and FTIR spectroscopies. It was found that both blocks of the PCL-PBD diblock copolymer are included in the U-IC channels while only the terminal PCL blocks of the PCL-PEO-PCL triblock copolymer are included. The structure of the PCL-PBD-U-IC appears to be a combination of the traditional hexagonal form with narrow ca. 5.5 A channels surrounding the PCL blocks, while the PBD blocks are included in an expanded tetragonal structure observed previously for PEO(oligomer)-U-IC and polypropylene-U-IC, where the urea matrix channel diameter is believed to be expanded beyond 7 A. This might explain how the PBD blocks, which contain 12% 1,2 units with bulky -CH=CH 2 side chains, are accommodated in the U-IC channels. Similarly, in the PCL-PEO-PCL-U-IC, where only the terminal PCL blocks are included, the IC structure appears very similar to the usual narrow channel, hexagonal structure as found, for example, in PCL-U-IC, the IC between the PCL homopolymer and urea. As a consequence, we may observe PCL blocks in two distinct U-IC environments and may compare their behaviors to those of PCL chains in the homopolymer PCL-U-IC and homopolymer and block copolymer bulk crystals. In addition, T lΡ measurements of 1 H spin diffusion reveal structural aspects of the block copolymer-U-ICs, and the isolation of U-IC included polymer chains from their neighbors may permit the probing of 1-dimensional 'H spin diffusion by observing the T 1 ρ( 1 H) relaxation in these block copolymer-U-ICs.