Poly(propylene)/montmorillonite/polypyrrole composites: structure and conductivity

Poly(propylene)/montmorillonite/polypyrrole (PP/MMT/PPy)composites were prepared by oxidative polymerization of pyrrole in the presence of dispersed poly(propylene)(PP)and montmorillonite (MMT)particles in aqueous solution of an anionic surfactant, dodecylbenzenesulfonic acid (DBSA), or in water/methanol solution. During the oxidative polymerization of pyrrole the exfoliated MMT rearranges to multilayered MMT intercalated with polypyrrole (PPy). The degree of intercalation depends on the charge compensation of the negatively charged MMT-layers. Favored interlayer distances have been detected by wide angle X-ray scattering, which are independent of the amount of PPy formed in the system. Excess PPy is located at the surface of the multilayered structures ofMMTas well as at the surface of the PP particles present. The composites were processed to flat sheets. Morphology and, therefore, electrical conductivity strongly depend on the type of processing, but also on the amount of conducting PPy present in the composite and on the reaction medium used for PPy synthesis. Higher conductivities and improved stability against shear are observed when MMT is present in the composite samples compared to samples devoid of MMT.