Solid‐state ¹³C NMR characterization of annealed poly (<i>p</i>‐phenylene vinylene) PPV Films

Abstract

Abstract Solid‐state 13 C cross‐polarization magic‐angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectra have been obtained for annealed films of poly ( p ‐phenylene vinylene) (PPV), prepared through the precursor route and for a deuterated PPV‐d 4 , poly ( p ‐2,3,5,6 tetradeuterophenylene vinylene). 13 C CPMAS spectra of PPV are of high resolution, typically characteristic of a nearly fully crystalline structure. All four phenylene and vinylene resonances have been assigned, and for stretched films the 13 C CPMAS linewidth and the quality of crystallinity are independent of the draw ratio. 13 C CPMAS resolution and crystallite size (as determined by transmission electron microscopy, TEM) depend upon final annealing temperature. The greatest NMR resolution and largest crystallite size are obtained for films annealed at 300°C. The 13 C CPMAS NMR spectra show the presence of phenylene ring 180° rotational jumps, and 13 C CPMAS resolution is affected by rotational disorder about phenylene‐vinylene bonds. NMR data show that PPV films possess molecular motion at elevated temperatures. Enhancement of this motion during annealing may provide a means for improving the quality of PPV crystallinity.