Sulfonated polyphenylacetylene/multiwalled carbon nanotubes (SPPA/MWCNTs) composites were prepared by blending SPPA with MWCNTs in ultrasonic bath. Conductive properties and conductive mechanism for the SPPA/MWCNTs were investigated using X-ray photoelectron spectroscopy (XPS), UV-Vis-NIR spectrometer (UV), X-ray diffraction (XRD), four-point probe and field emission scanning electron microscopy (FESEM) techniques. The results indicate that charge transfer occurred between SPPA and MWCNTs, SPPA were doped by MWCNTs, and some interaction existed between MWCNTs and SPPA, originating from charge transfer. The dependencies of conductivity on temperature showed negative temperature coefficient (NTC) of resistance. The composite conductivities had two obvious increases. The conductive mechanism is supposed as follows. SPPA were both filled and doped by MWCNTs, and two types of conductive systems existed in the SPPA/MWCNTs composites. One was formed by connecting of conductive units (conductive units were formed via SPPA wrapping MWCNTs); and the other formed by contacting of MWCNTs. Furthermore, a theoretical model was built to explain the conductive mechanism.

Key words: sulfonated polyphenylacetylene, multiwalled carbon nanotube, composite, conductive mechanism, fill, doping