One- and Two-Dimensional Solid-State 13C NMR Analyses of the Solid Structure and Molecular Motion of Poly(ε-caprolactone) Isothermally Crystallized from the Melt

作者：Hironori Kaji, Fumitaka Horii · 发表于：Macromolecules · 年份：1997 · DOI：10.1021/ma970167l · 被引用次数：50 · 研究领域：Advanced NMR Techniques and Applications、Advanced Battery Materials and Technologies、NMR spectroscopy and applications

The crystalline−noncrystalline structure and molecular motion of poly(ε-caprolactone) (PCL) isothermally crystallized from the melt have been investigated by one- and two-dimensional solid-state 13 C NMR spectroscopy. The 13 C spin−lattice relaxation time ( T 1C ) analysis reveals that the PCL sample contains three components with different T 1C values, which are assignable to the crystalline, mobile crystalline, and noncrystalline components. By the 13 C spin−spin relaxation time ( T 2C ) analysis, it is found that the noncrystalline component can be further resolved into the crystalline−amorphous interfacial, and amorphous components. The mass fractions of the crystalline, interfacial, and amorphous components are finally determined to be 0.42, 0.30, and 0.28, respectively. In the crystalline region, different molecular mobilities along the methylene sequence are suggested through the difference in T 1C value for the constituting carbons. More detailed molecular motion in the crystalline region has been characterized by the analysis of the 13 C chemical shift anisotropy (CSA) in terms of the two-site exchange model. 13 C CSA spectra of the individual carbons are successfully recorded by using the two-dimensional switching angle sample spinning technique. The CSA spectrum of the carbonyl carbon exhibit that the carbonyl carbon is almost in the rigid state or undergoes the jump motion around the molecular chain axis with a jump angle less than 30°. In contrast, methylene carb...