Microtubules of polypyrrole synthesized by an electrochemical template-free method

Microtubules of polypyrrole (PPy) were synthesized by an electrochemical te mplate-free method in the presence of beta -naphthalenesulfonic acid (beta -NSA) as a dopant for the first time. The influence of electrochemical poly merization conditions, such as material of the working electrode, the conce ntration of beta -NSA and pyrrole monomer, current density and polymerizati on time on the tubular morphology of PPy-NSA was systematically investigate d. PPy-NSA tubules 0.8-2.0 mum in diameter and 15.0-30.0 mum in length were obtained when a non-corrosive steel plate was used as the working electrod e, and the size of the tubules was affected by other polymerization conditi ons. The molecular structure of the tubules was characterized by FTIR and X -ray diffraction, indicating that their polymer chains are similar to granu lar PPy synthesized by other chemical or electrochemical methods, and the t ubules were amorphous. The conductivity of the tubules at room temperature was found to be about 5.0 S cm(-1) and the temperature dependence of the co nductivity followed a two-dimensional Variable Range Hopping (2D-VRH) model . It was proposed that the absorbed micelles of beta -NSA, which result fro m the surfactant characteristics of beta -NSA dopant on the working electro de, act like templates in forming PPy-NSA tubules by this new method.