Investigation of Layered Structures of Synthetic Smectite/Polypyrrole Composite Powders Prepared by Vapor Phase Polymerization

Abstract

Composite powders of Fe3+-exchanged synthetic smectite and polypyrrole were prepared by using pyrrole vapor, and their layered structures were investigated by Fourier transform-infrared spectrophotometer (FT-IR), X-ray diffractometer (XRD) and Thermogravimeter-Differential thermal analyzer (TG-DTA). The results showed that chemical oxidative polymerization of the pyrrole occurred in the interlayer spaces between silicate layers; the increment of the polypyrrole depended on vapor phase reaction time. The amount of polypyrrole and interplanar spacing of the composite powders increased gradually, and it was concluded that two layers of polypyrrole formed on both sides of Fe3+ in each space. The rate determining step of the reaction was the absorption and the diffusion of the pyrrole into the interlayer spaces. By TG-DTA, it was found that the thermal stability of the polypyrrole in the composite powders improved, for the polypyrrole being strongly restrained from burning and pyrolyzing in nanoscale spaces between silicate layers. A part of the polypyrrole was carbonized when the composite powders was heated up in N2 with gradually rising temperature. The laminated carbon influenced the structural change of silicate layers. An increment of carbonization suggested that the laminated polypyrrole changed into a precursor for carbon under suitable conditions.