Synthesis of novel hexagonal micro-sheet polypyrrole and micro-sheet polypyrrole with grooves in the presence of α-cyclodextrin/Acid Red G inclusion compounds

Abstract

Novel hexagonal micro-sheet polypyrrole (PPy) was synthesized via the self-assembly method in the aqueous solution containing α-cyclodextrin (α-CD)/5-acetamido-4-hydroxyl-3-(phenyliazenyl) naphthalene-2,7-disulfonic acid (Acid Red G) inclusion compounds (α-CD/ARG ICs) and ferrous cations. And micro-sheet polypyrrole with grooves was obtained by dipping the micro-sheet PPy into alkaline solution for 12 h. The existence of α-CD/ARG ICs in aqueous solution was testified by UV–vis spectra. Scanning electron microscopy (SEM) images revealed that the micro-sheet PPy was over 10 μm in average length, 0.6–10 μm in broadbrim and 100–200 nm in thickness. The conductivities of the micro-sheet PPy were in the range from 2.78 to 12.50 S cm −1 and the conductivities of the micro-sheet PPy with grooves were in the range from 3.70 to 7.69 S cm −1. Cyclic voltammograms (CVs) were measured to examine the electrochemical behaviors of the prepared PPy, and the oxidation peak of micro-sheet PPy was increased to 1.34 V which was higher than those of other PPy samples. The experimental conditions were also optimized, and the optimization of experimental conditions was the quantities of pyrrole monomers, α-cyclodextrin and Acid Red G were 20, 4 and 4 mmol, respectively, and the perfect micro-sheet PPy was synthesized at 5 °C and no-stirring for over 12 h. It was found that the complex aggregations of α-CD/ARG ICs and ferrous cations might have the function as a “template” during the polymerization of pyrrole monomers, but this “template” was broken off from the prepared micro-sheet PPy in the alkaline condition.