Phase Structure and helical jump motion of poly(ethylene oxide)/LiCF ₃SO₃ crystalline complex: A high-resolution solid-state ¹³C NMR approach

By employing solid-state high-resolution ¹³C nuclear magnetic resonance (NMR), we found that the helical jump motion of crystalline poly(ethylene oxide) (PEO) segments only exists for the PEO₃/LiF ₃SO₃ complexes with the molecular weights of PEO larger than 2 × 10³ g mol^-1, and the helical jump rate increases with increasing the molecular weight of PEO. It is demonstrated that the helical jump rate of crystalline PEO segments depends on the relative content and chain mobility of the amorphous structures for PEO-alkali metal salt complexes. The sufficient amount of amorphous phase is the necessary condition for the helical jump motion to happen, and the chain motion in the amorphous phase might be the driving force for the helical jump motion of the crystalline PEO segments. On the basis of the above recognition, we tend to believe that the helical jump motion is corresponding to the movement of an entire PEO chain embedded in the crystallites.