Multi-walled carbon nanotubes (MWNT) were used as filler to prepare poly(3-octylthiophene) (P3OT)/MWNT composites in chloroform, which were ultrasound blended. When the content of MWNTs was 3%, the conductivity of composite almost attained that of pure MWNT (1.43 S•m－1). Fourier transform infrared spectroscopy (FTIR), thermo-gravimetry (TG), X-ray spectroscopy (XPS), ultraviolet-visible absorption spectra (UV-Vis) and field emission scanning electron microscopy (FESEM) were employed to characterize these composites. The results suggest that π-π system is formed between the delocalized electrons in MWNT and the π-electrons in the conjugated main chain of P3OT. The effectively conjugated chain of P3OT is prolonged by MWNTs. The doped P3OT has a high conductivity and can improve the conductivity of composites. MWNT was combined with the doped P3OT to form individual conductive units, which play a key role in forming the conducting net of composites.

Key words: poly(3-octylthiophene), carbon nanotube, individual conductive unit, composite