2.
Experimental
2.1 Functionalization of SWCNT
The single-walled carbon nanotubes was used as received. One gram of SWCNT was
first ultrasonically treated with a 3:1 mixture of concentrated H 2SO4 and HNO3 at 50 0C
for 4 h, which produced carboxylic acid groups at the defect sites and thus improved the
solubility of the SWCNT in HCl solution. After cooling to room temperature, the
mixture was centrifuged at 4000 rev/min in order to separate the treated SWCNT from
mixture, and then filtrated with 0.22µm porous filter paper. The filtrated solid was
washed thoroughly by deionized water until no residual acid was present. The filtered
sample was then dried in a furnace at 80 0C for 6 h .The sample was abbreviated as f-
SWCNT .
2.2 Prepare PANI and PANI/F-SWCNT thin films
Aniline monomer ,distilled water , ammonium persulfate and hydrochloric acid (HCL)
were used as received. The polyaniline thin films (PANI) was chemically synthesized
by in-situ method by using aniline monomer and ammonium persulfate ((NH 4)2S2O8) as
oxidant agent. 1 M of HCL placed in a 250 mL beaker, during the polymerization the
beaker was kept inside a vessel containing an ice at a temperature of (0-5)°C.
Separately, 15g of (NH4)2S2O8 was dissolved in 50mL of 1 M HCL, and then added as
dropwise into the beaker containing the aniline acid solution during a period of 15 min
and under constant stirring. After a few seconds, growth of green coloured polyaniline
was seen and slowly the color dispersed into the aqueous solution and within 5
minutes the aqueous solution became dark green. During this entire process, the reaction
medium was kept in (0-5) °C .
PANI films was produced on glass slides. Prior to use the glasses, they washed with
acetone and distilled water via ultrasonic. These glasses were made to adhere to an
adhesive tape to allow for the coating of the glass on one side only. Using plastic
clamps, the glasses was placed in the 250 ml beaker after the solutions of aniline
monomer and of an oxidant were mixed, all glasses removed from the medium after the
reaction time (30 min), it is observed that this is the best time to obtain uniform thin
films. The glasses were again placed in a beaker containing a solution of 2 ml aniline in
100 ml 1 M HCI, at (0-5) °C. This step was necessary in order to reduce any oxidized
pernigraniline form of polymer in the emeraldine oxidation state. After that the glasses
were rinsed with 1 M HCl to remove the adhering PANI precipitate, separated from the
tape, rinsed with acetone, and left to dry in air at room temperature.
For preparing PANI/ f-SWCNT nanocomposite thin films, a different content of f-
SWCNTs (0.02 , 0.04 , 0.06 , 0.08 and 0.1 g) were ultrasonicated in 50 ml of 1M HCL
for 30 min, then 5ml of aniline monomer added to the solution under constant stirring
for 30 min. Ammonium persulfate (APS) was slowly added dropwise into aniline/f-
SWCNT solution with constant stirring at a reaction temperature of 0– 5 0C for 30
min. The rest of procedure of obtained PANI/ f-SWCNT nanocomposite thin films is
similar to that of PANI thin films . The measured thickness of the films was about
( 200±20) nm.
Transmittance and absorbance spectrum at normal incidence in the range (300 –
900) nm were utilized to carry out the optical measurements of thin films deposited
on glass substrate , the type of UV-VIS spectrophotometer is ( SHIMADZU)(UV-
1600/1700 series) .The infrared analysis of wavenumber was carried out by using
SIDCO England series FT-IR spectrometer over the range 650 to 2500 cm -1. The X-
ray diffractrometer type SHIMADZU, power diffraction system with Cu-Kα X-ray
tube (λ = 1.54056 Ǻ) is used. The X-ray scans are performed between 2θ values of 5
and 80°. Scanning Electron Microscopy (SEM) of the type "TESCAN MIRA3" was
used
