ABSTRACT
Aluminosilicate-based nanocomposites containing multi-layer graphene were prepared from polyaniline/montmorillonite intercalate in two different forms: tablets and thin layers. Starting materials, polyaniline/montmorillonite powder and polyaniline/montmorillonite layers deposited on quartz glass, were prepared by in situ polymerization of aniline in presence of montmorillonite particles. Powder was compacted into tablets using pressure 400 MPa. Samples were calcined at 1300 °C in argon atmosphere and multi-layer graphene was formed from polyaniline in both cases as confirmed by Raman microspectroscopy. Changes in morphology and surface conductivity of uncalcined and calcined samples were observed using atomic force microscopy and conductive atomic force microscopy. Also the differences between surface and internal volume of tablets were studied. Conductive atomic force microscopy revealed that the most conductive areas can be found solely on the edges of aluminosilicate particles formed from montmorillonite during calcination process. Detailed observation of multi-layer graphene in these areas was performed using transmission electron microscopy.
ABSTRACT
Regularly arranged chains strongly affect the electrical conductivity of conductive polymers (e.g., polypyrrole). One of the easiest ways to achieve this arrangement is the insertion of the polymer into the interlayer space of solid inorganic layered matrix, i.e., the intercalation process. Among various kinds of layered materials, the clay minerals, especially the smectite group, deserves particular attention. Negative charge of smectite layers helps the intercalation process resulting in higher conductivity of the polymer in clay/polymer intercalates. Characterization of stevensite-rich Moroccan clay and intercalation of electrically conductive polypyrrole into stevensite-rich Moroccan clay in order to obtain material with higher conductivity in comparison with pure polypyrrole were two main purposes of this work. Two forms of stevensite/polypyrrole nanocomposites were studied: powder and pressed tablets. X-ray fluorescence spectroscopy, X-ray diffraction analysis, atomic force microscopy, thermogravimetry, infrared spectroscopy, Raman microspectroscopy, and scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy were used to study the composition and structure of the nanocomposites. Measurement of electrical conductivity of polypyrrole in stevensite/polypyrrole nanocomposites revealed enhanced conductivity for all samples and also anisotropy in the conductivity of the samples pressed in the tablets.
