Hong You-Lee, Chen Wei, Yuan Shichen, Kang Jia, Miyoshi Toshikazu
Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States.
ACS Macro Lett. 2016 Mar 15;5(3):355-358. doi: 10.1021/acsmacrolett.6b00040. Epub 2016 Mar 2.
Over the last half century, a chain-folding structure of semicrystalline polymers has been debated in polymer science. Recently, C-C double quantum (DQ) NMR spectroscopy combined with C selective isotope labeling has been developed to investigate re-entrance sites of the folded chains, mean values of adjacent re-entry number ⟨⟩ and fraction ⟨⟩ of semicrystalline polymers. This viewpoint highlights the versatile approaches of using solid-state (ss) NMR and isotope labeling for revealing (i) chain trajectory in melt- and solution-grown crystals, (ii) conformation of the folded chains in single crystals, (iii) self-folding in the early stage of crystallization, and (iv) unfolding of the folded chains under stretching.
在过去的半个世纪里，半结晶聚合物的链折叠结构在高分子科学领域一直存在争议。最近，结合碳选择性同位素标记的碳-碳双量子（DQ）核磁共振光谱技术已被开发出来，用于研究半结晶聚合物折叠链的再入位点、相邻再入数的平均值〈 〉以及分数〈 〉。这一观点突出了利用固态（ss）核磁共振和同位素标记来揭示（i）熔体生长和溶液生长晶体中的链轨迹，（ii）单晶中折叠链的构象，（iii）结晶早期的自折叠，以及（iv）拉伸下折叠链的展开等多种方法。
