Synthesis of a Polyaniline Nanoparticle Using a Solution Plasma Process with an Ar Gas Bubble Channel

Abstract

This work researched polymerization of liquid aniline monomer by solution plasma with a gas bubble channel and investigated characteristics of solution plasma and polyaniline (PANI). The injected gas bubble channel in the proposed solution plasma process (SPP) played a significant role in producing a stable discharge in liquid aniline monomer at a low voltage and furthermore enhancing the contact surface area between liquid aniline monomer and plasma, thereby achieving polymerization on the boundary of the liquid aniline monomer and plasma. Solution plasma properties were analyzed with voltage–current, optical emission spectroscopy, and high-speed camera. Conductivity, percentage yield, and firing voltage of PANI nanoparticle dispersed solution were measured. To investigate the characteristics of synthesized PANI nanoparticles, field emission scanning electron microscopy, dynamic light scattering, transmission electron microscopy, selective area electron diffraction (SAED) pattern, Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography, 1H-nuclear magnetic resonance (1H-NMR), and X-ray photo spectroscopy (XPS) were examined. The FTIR, 1H-NMR, and XPS analysis showed the PANI characteristic peaks with evidence that some quinoid and benzene rings were broken by the solution plasma process with a gas bubble channel. The results indicate that PANI nanoparticles have a spherical shape with a size between 25 and 35 nm. The SAED pattern shows the amorphous pattern.

Effects of a Dielectric Barrier Discharge (DBD) on Characteristics of Polyaniline Nanoparticles Synthesized by a Solution Plasma Process with an Ar Gas Bubble Channel

“…Figure 1 a shows the schematic diagram of an experimental apparatus with the proposed DBD electrode structure employed in this study. Since the discharge is very difficult to produce in a solution, especially a liquid aniline monomer with a high dielectric strength, the concept of a bubble channel has been proposed to be able to form a discharge in a gaseous state in a liquid aniline monomer [ 29 ]. Figure 1 b shows a schematic of the DC electrode structure where the pair of pin-type tungsten (W) electrodes face each other in the previous study [ 29 ].…”

“…Since the discharge is very difficult to produce in a solution, especially a liquid aniline monomer with a high dielectric strength, the concept of a bubble channel has been proposed to be able to form a discharge in a gaseous state in a liquid aniline monomer [ 29 ]. Figure 1 b shows a schematic of the DC electrode structure where the pair of pin-type tungsten (W) electrodes face each other in the previous study [ 29 ]. When the Ar gas was fed through both quartz tubes, an Ar bubble channel was formed to surround both of the W electrodes, thereby playing a significant role in providing a gaseous discharge path in liquid aniline.…”

“…Accordingly, the discharge could be produced only during a period of gas-bubble channel formation, as shown in Figure 2 a. We reported the temporal evolution of discharge formation within the bubble channel by a high-speed camera in the previous DC electrode structure [ 29 ]. In this study, however, the intensity of the DBD was too weak to take a discharge image using a high-speed camera, such that it was monitored with an ICCD camera.…”

“…Figure 2 b shows the discharge images taken in a shutter mode with an exposure time of 5 ms using an ICCD camera. In the previous DC electrode structure, since the electric field was concentrated at the end of the W electrode, the discharge was mainly generated from the end of the cathode to the upper surface area of the anode along the Ar bubble channel in the discharge region placed between two quartz tubes [ 29 ]. In the proposed DBD electrode structure, however, the discharge path of a DBD must be created through the quartz tube under the cylindrical Cu electrode.…”

“…The pulsed DC streamer discharge within the Ar bubble channel could be stably generated with a significantly reduced firing voltage. It has also been demonstrated that polyaniline nanoparticles (PANI NPs) can be synthesized by SPP [ 29 ]. Nevertheless, a strong DC streamer discharge occurred between the two pin-type metal electrodes in the Ar bubble channel, resulting in contamination of the electrode erosion.…”