Preparation and characterization of polyindole nanofibers by electrospinning method

Polyindole nanofibers with diameter ranging from 770 nm to 250 nm were firstly fabricated by an electrospinning method. Chemically synthesized polyindole was dissolved in acetonitrile to make polymer solution under ultrasonification. Electrospinning of polyindole was then carried out under electrical field strength of 1.0 kV/cm. The electrospun polyindole nanofibers exhibited smooth surface and the diameter of the fibers was ranged from 768 nm to 255 nm. The specific surface areas of polyindole nanofibers were ranged from 32 to 65 m2/g, which is significantly higher than that of the powder with same volume. The electrical conductivity of the polyindole nanofibers can reach 0.24 S/cm, which is much higher than that of the polyindole film. The polyindole nanofibers showed high thermal stability with glass transition temperature (Tg) around 132 °C and melting point (Tm) around 239 °C. The crystallinity of polyindole nanofibers was higher than that of polyindole film due to the formation of ordered molecule chains during the electrospinning. Cyclic voltammetry test results revealed that the doping and de-doping processes of BF4− ions were reversible and polyindole nanofibers had high electronically activity in the electrolytic solution containing LiBF4.