Electrically conducting polypyrrole fibers spun by electrospinning

Electrospinning is a process that produces continuous fibers with the diameters in the range of micron or sub-micron, where many solution jets are split by the repulsive electric force imposed on a polymer solution or melt. In this study we fabricated electrically conducting polypyrrole (PPy) fiber nonwoven web using the electrospinning technique and investigated the properties of the fiber and the web. Highly conducting soluble PPy was first chemically polymerized using ammonium persulfate (APS) as the oxidant and dodecylbenzene sulfonic acid (DBSA) as the dopant source. Electrical conductivity and solubility of the resulting PPy powder significantly varied with the polymerization conditions such as the concentration of the oxidant, polymerization temperature and time. PPy solution with the appropriate concentration for the electrospinning was prepared by dissolving PPy powder in chloroform with extra DBSA. Electrospinning of the PPy fiber was then carried out under applying electrical voltage of 30 to 45 kV. The electrospun PPy fiber nonwoven web was finally washed with methanol to remove the remaining extra DBSA in the fiber, resulting in electrically conducting PPy nonwoven web. The PPy fibers exhibited circular cross-section and the extraordinarily smooth surface and the diameter of the fibers was about 3 μm. The electrical conductivity of the compressed PPy nonwoven web was about 0.5 S/cm, which is slightly higher than those of the powder or the cast films, possibly because of molecular orientation induced during the electrospinning.