EPR investigations of mesoscopic disorder in polypyrrole

Electron spin resonance experiments on polypyrrole films show that oxygen gas increases the asymmetry ratio (A/B) for the highly conducting sample synthesized at -40 °C, decreases A/B (after an early increase) for the sample synthesized at 0 °C, and has no effect on the lowest conductivity sample prepared at 20 °C. These results support a heterogeneous model for these materials with less disorder in samples synthesized at low temperatures compared to those synthesized at high temperatures, and with oxygen having different effects with different time scales in ordered and disordered regions.