Yuan Shichen, Li Zhen, Hong You-Lee, Ke Yutian, Kang Jia, Kamimura Akihiro, Otsubo Akihiro, Miyoshi Toshikazu
Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States.
SunAllomer, Ltd., 3-2 Yako 2-chome Kawasaki-ku, Kawasaki 210-0863, Japan.
ACS Macro Lett. 2015 Dec 15;4(12):1382-1385. doi: 10.1021/acsmacrolett.5b00818. Epub 2015 Nov 25.
Understanding the structure formation of an ordered domain in the early stage of crystallization is one of the long-standing issues in polymer science. In this study, we investigate the chain trajectory of polypropylene (PP) formed via rapid and deep quenching, using solid-state NMR spectroscopy. Comparisons of experimental and simulated C-C double quantum (DQ) buildup curves demonstrated that individual PP chains adopt adjacent re-entry sequences with an average folding number ⟨⟩ = 3-4 in the mesomorphic form, assuming an adjacent re-entry fraction ⟨⟩ of 100%. Therefore, long flexible polymer chains naturally fold in the early stage of crystallization, and folding-initiated nucleation results in formation of mesomorphic nanodomains.
理解结晶早期有序域的结构形成是高分子科学中长期存在的问题之一。在本研究中，我们使用固态核磁共振光谱研究了通过快速深度淬火形成的聚丙烯（PP）的链轨迹。实验和模拟的C-C双量子（DQ）积累曲线的比较表明，假设相邻再入分数⟨⟩为100%，单个PP链在介晶形式中采用平均折叠数⟨⟩ = 3-4的相邻再入序列。因此，长柔性聚合物链在结晶早期自然折叠，折叠引发的成核导致介晶纳米域的形成。
