Enhanced conductive polymer nanocomposite by foam structure and polyelectrolyte encapsulated on carbon nanotubes

Improved conductive polystyrene (PS)-based nanocomposite filled with ultralow addition of multi-walled carbon nanotubes (MWCNTs) were fabricated by concentrated emulsion polymerization. First, the foam structure was constructed to compress MWCNTs into a thin polymer skeleton and enhance the electrical conductivity of the nanocomposite. Second, a polyelectrolyte poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was introduced onto MWCNTs to reduce the noncontact resistivity within the inter-tube junctions. The effect of porous morphology, the loading phase and content of MWCNTs, and the synergetic effect of MWCNTs and PEDOT:PSS on the electrical conductivity of the nanocomposites were investigated. It was found that the foam structure of nanocomposite with a specific location of conductive fillers can strongly reduce the percolation threshold. In addition, the conductivities of the nanocomposites could be controlled by the porous structure. As a result, the percolation threshold of 0.3 wt% PEDOT:PSS/MWCNTs to PS matrix was achieved, and the highest conductivity was obtained from the foam structure with the thinnest pore wall and the appropriate ratio of PEDOT:PSS/MWCNTs.