Crystallization of Homopolymers Confined in Spherical or Cylindrical Nanodomains
Crystallization of Homopolymers Confined in Spherical or Cylindrical Nanodomains
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DOI：
10.1021/ma7027903
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发表时间：
2008-02
期刊：
影响因子：
5.5
通讯作者：
S. Nojima;Yuya Ohguma;Shingo Namiki;Takashi Ishizone;K. Yamaguchi
中科院分区：
文献类型：
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作者：
S. Nojima;Yuya Ohguma;Shingo Namiki;Takashi Ishizone;K. Yamaguchi
导论.从聚合物材料纳米结构控制的角度来看，在结晶嵌段共聚物中观察到的空间受限结晶提供了一个有趣的研究课题。1众所周知，孤立的纳米域（即球体或圆柱体）会影响组成块的结晶，从而导致结晶温度和结晶度显著降低，2 - 7其中我们可以考虑同时影响结晶过程的两个主要因素：（1）围绕结晶块的纳米域的空间限制和（2）纳米域界面处的束缚链限制（图1a）。为了分别理解这些因素对结晶行为的影响，有必要制备这样的体系，其中结晶均聚物被限制在球形或圆柱形纳米畴内（图1b）并研究两种系统之间结晶行为的差异（图1中的a/B或B/c）.制备这样的体系并不容易，需要有新的想法来做. Ho等8研究了聚（α-己内酯）（PCL，[-（CH2）5-CO-O-] n）均聚物在PCL和聚苯乙烯-嵌段-聚（乙烯-丙烯）（PS-b-PEP）的二元共混物中的共混物，其中PCL位于微相分离的PS-b-PEP层之间，并最终被限制在由PS和PEP层组成的层状纳米畴内。他们得出结论，受限PCL的熔融温度、结晶度和结晶速率与没有任何空间限制的散装PCL的熔融温度、结晶度和结晶速率显著不同。近年来，一些研究小组研究了均聚物在纳米多孔氧化铝中的结晶行为，并报道了结晶行为与纳米棒性质之间的有趣关系。9-11一些计算机模拟也已经进行了均聚物结晶在孤立的纳米畴。十二、十三
Introduction. Spatially confined crystallization observed in crystalline block copolymers provides an interesting research subject from the viewpoint of nanostructural control in polymer materials. 1 It is well-known that isolated nanodomains (ie, spheres or cylinders) affect the crystallization of constituent blocks to yield a considerable decrease in the crystallization temperature and crystallinity, 2-7 where we can consider two principal factors which simultaneously affect the crystallization process:(1) spatial confinement by nanodomains surrounding the crystalline blocks and (2) chain confinement by tethering at the nanodomain interface (Figure 1a). In order to understand the effects of these factors separately on the crystallization behavior, it is necessary to prepare such a system where crystalline homopolymers are confined within spherical or cylindrical nanodomains (Figure 1b) and to investigate the differences in crystallization behavior between two systems (a/b or b/c in Figure 1).It is not easy to prepare such a system, and new ideas are necessary to do it. Ho et al. 8 studied the crystallization behavior of poly (ϵ-caprolactone)(PCL,[-(CH2) 5-CO-O-] n) homopolymers in a binary blend of PCL and polystyrene-block-poly-(ethylene-propylene)(PS-b-PEP), where PCL was localized between microphase-separated PS-b-PEP layers and eventually confined within lamellar nanodomains consisting of PS and PEP layers. They concluded that the melting temperature, crystallinity, and crystallization rate of confined PCL were significantly different from those of bulk PCL without any spatial confinement. Recently some research groups studied the crystallization of homopolymers confined in nanoporous alumina and reported the interesting relationship between the crystallization behavior and the properties of nanorods. 9-11 Some computer simulations have also been performed for homopolymer crystallization in isolated nanodomains. 12, 13