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

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 (similar to 100 MHz) for the terminal CH3 group. A correlation between the motional parameters and the photoluminescent behaviors as a function of temperature was observed and is discussed.711