Synthesis and influence conditions study of micro-sheet polypyrrole

A novel sheet micro-structure polypyrrole (PPy) was synthesized via a self-assembly method using the inclusion compound of a-cyclodextrin (α-CD) with 5-(acetylamino)-4-hydroxy-3-(phenylazo)-2, 7- naphthalenedisulfonic acid (Acid Red G, ARG) as the dopant and FeCl₃ as the oxidant. The structures and morphologies of the synthesized sheet PPy were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Flourier-transform infrared (FTIR) spectroscopy. The results indicated that these sheet PPy doped with the inclusion compound of ct-cyclodextrin with ARG showed 1 ∼ 10 μm in width, 10 ∼ 20 μm in length and the thickness was about 200 nm under no-stirring condition. At the same time, the influence of temperature, the concentrations of various reactants and reaction time on the morphology of the synthesized sheet PPy was investigated. Based on the research results, the optimized synthesis condition for the PPy tubules was obtained. The best conditions of forming PPy micro-sheet are as follows: the reaction temperature is 5°C, the concentrations of pyrrole, α -cyclodextrin and ARG are 0. 31 mol/L, 0. 067 mol/L and 0. 067 mol/L, the reaction time is above 12 h. The formation mechanism of the sheet PPy was also discussed. Characterization results of PPy (the elements and contents, XRF) and the reaction intermediates revealed the formation mechanism of PPy micro-sheet is that the especial aggregation of the complexes of Fe²⁺ and α-CD/ARG inclusion compounds was considered as the "template" in the synthesis process of the micro-sheet PPy. Because of the layer arrangement of α-CD/ARG inclusion compounds, the -SO₃H groups of ARG molecules were arranged in one surface of the layer structure. Then this finally induced the polymerization reaction and continuous growth of pyrrole monomers on one surface of the aggregation of the complexes "template".