Abstract:

Electrically conductive composites were prepared via the  chemical oxidative polymerization of pyrrole monomer in polystyrene(PS) and zinc neutralized sulfonated polystyrene(Zn-SPS) films under supercritical carbon dioxide(SC-CO₂) circumstance. The strong swelling effect of SC-CO₂ made polypyrrole(PPy) particles not only formed on the surface, but also incorporated into the film,  resulting in a homogenous structure and a relatively higher conductivity. By comparison, the composite prepared in aqueous solution shows a skin-core structure and a conductivity of 3 to 4 orders of magnitude lower than that of the former  due to the diffusion controlled process of pyrrole monomer. The percolation thresholds of PS/PPy and Zn-SPS/PPy composites are 6.2% and 2.7% of volume fractions of  PPy, respectively, much lower than a theoretically predicted value of 16%. Moreover, the conductive composites prepared under SC-CO₂ circumstance show higher thermal stability, especially in the high-temperature region.

Key words: Supercritical carbon dioxide; Polypyrrole; Conductive composite