Solid-state nuclear magnetic resonance study of relaxation processes in MEH-PPV

Abstract

Solid-state nuclear magnetic resonance methods were used to study molecular dynamics of MEH-PPV at different frequency ranges varying from 1 Hz to 100 MHz. The results showed that in the 213 to 323 K temperature range, the motion in the polymer backbone is predominantly slow (Hz--kHz) involving small angle librations, which occurs with a distribution of correlation times. In the side chain, two motional regimes were identified: Intermediate regime motion (1--50 kHz) for all chemical groups and, additionally, fast rotation $(\ensuremath{\sim}100\phantom{\rule{0.3em}{0ex}}\mathrm{MHz})$ for the terminal $\mathrm{C}{\mathrm{H}}_{3}$ group. A correlation between the motional parameters and the photoluminescent behaviors as a function of temperature was observed and is discussed.