Preparation and Characterization of Montmorillonite/Polypyrrole Nanocomposites by In-Situ Chemical Polymerization

Abstract

After prior ultrasonic treatment of montmorillorite (MMT), montmorillonite/polypyrrole (MMT/PPy) nanocomposites containing 10–80% PPy were prepared by in-situ chemical polymerization of pyrrole at 0°C in the presence of MMT in aqueous solution with FeCl3 as oxidant and dopant. X-ray diffraction showed an increase in the interlayer spacing from 1.26 nm for MMT to 1.55 nm for MMT/PPy-10% and 1.96 nm for MMT/PPy-80%, signifying PPy was intercalated into the MMT galleries. Infrared spectra revealed the shifts of C-N stretching vibration and in-plane deformation bands, as well as the N-H vibration peaks of PPy, suggesting the presence of interfacial interactions between MMT and PPy. Scanning electron microscopy micrographs showed a flake-like morphology for the MMT/PPy nanocomposites and the obtained PPy retained this kind of morphology after removal of MMT from the composites by Hydrofluoric acid etching, while the pristine PPy prepared under the same condition exhibited globular particles. It was found for the first time that the conductivity of MMT/PPy with more than 50% PPy was higher than that of pristine PPy, i.e. 2.72 S/cm, 3.68 S/cm, and 4.81 S/cm for MMT/PPy containing 50%, 60%, and 80% PPy, while the pristine PPy conductivity was 2.71 S/cm. Thermal gravimetric analysis suggested that the introduction of MMT clay resulted in improvement of thermal stability for the obtained nanocomposites.