Production of montmorillonite/polypyrrole nanocomposites through in situ oxidative polymerization of pyrrole: Effect of anionic and cationic surfactants on structure and properties
Résumé
Montmorillonite/polypyrrole (Mt/PPy) nanocomposites were prepared through in situ oxidative polymerization of pyrrole in aqueous dispersions of unmodified montmorillonite (Na+-Mt) with three different surfactants (dodecylbenzenesulfonic acid (DBSA), sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)), using iron (III) chloride hexahydrate (FeCl3 center dot 6H(2)O) as an oxidant. In order to investigate the effect of the anionic and cationic surfactants used in the pyrrole polymerization, Mt/PPy nanocomposites were also prepared without surfactant. The anionic surfactants promoted the intercalation and partial exfoliation of the clay, while clay polymer nanocomposites (CPN) prepared with cationic CTAB (Mt/PPy center dot CTAB) and without surfactant (Mt/PPy center dot Cl) were partially intercalated. High electrical conductivity (10.8 S cm(-1)) was observed for the Mt/PPy.SDS nanocomposites due to the highly site-specific interaction between the protonated PPy (N+) and the negatively-charged Si-O-Si groups of the Mt. Finally, the thermal stability of the CPN was higher than that found for the corresponding PPy samples, with the exception of the Mt/PPy.CTAB nanocomposite, due to the protective effect of the clay layers.