## 2 Results and Discussion
### Detailed iPC-APPJ Device and Optical, Electronical, and Discharge Characteristics
In addition, spectra from carbonaceous species, such as CN (388 nm \(B^{2}\Sigma\to X^{2}\Sigma\)), emitted during fragmentation and recombination processes of aniline monomer were only monitored for the case with the PTFE bottom cap. This means that the proposed iPC-APPJ can be suitable for sufficient fragmentation of the aniline monomer and an efficient generation of a new polymer in the recombination regions. Figure 3: Optical emission spectra measured in the recombination region of iPC-APPJ, with and without the PTFE bottom cap. Figure 2: Applied voltages, discharge currents, and optical intensities measured in the recombination region of iPC-APPJ, with and without the PTFE bottom cap. Functionalization and Characterization of Newly Synthesized pPANI Nanoparticles and Nanofibers Using iPC-APP  
Figure 4 shows the top-view and cross-section-view SEM images of the pPANI nanofibers with nanoparticle (NwN) thin film, grown for 5-40 min, on glass prepared using iPC-APPJ. No NwN were observed in the case without the PTFE bottom cap (not shown here). Whereas, in the case with the PTFE bottom cap, many NwNs were observed to be linked together in many irregular cross-linked networks, and porous networks were clearly observed in Figure 4a, meaning that the nanofibers and nanoparticles can be efficiently synthesized with the proposed iPC-APPJ. In addition, as shown in Figure 4a, the presence of pPANI nanofibers with a diameter range of 10-20 nm were clearly observed. As shown in Figure 4b-f, under various deposition times, the deposition rate was low during 5-min deposition. However, the deposition rates were increased significantly during 10-min deposition and maintained after 20 min at about 0.13-0.14 \(\upmu\)m\(\cdot\)min\({}^{-1}\) in the case of the PTFE bottom cap, meaning that the nano-size polymer could be grown rapidly during the plasma polymerization with the proposed iPC-APPJ. Figure 5 shows the TEM images of the pPANI nanoparticles prepared using iPC-APPJ. As shown in Figure 5, the pPANI nanoparticles, with a diameter range of 8-10 nm, were clearly observed. The particle sizes monitored using TEM are observed to be smaller than those measured using SEM, as expected for the dehydrated state of the TEM samples. The selected area's electron diffraction (SAED) pattern of pPANI nanoparticles (Figure 5c, inset) reveals the clear diffraction ring and spot of the polycrystalline characteristics [49; 50; 51; 52]. The polycrystalline characteristics of pPANI nanoparticles may be caused by many irregular cross-linked networks, characteristic of plasma polymerization. The TEM analysis of Figure 5 confirms that the plasma polymerization using the proposed iPC-APPJ can produce uniform pPANI nanoparticles of a very small size and polycrystalline characteristics. Figure 4: Scanning electron microscopy (SEM) images of plasma-polymerized aniline (pPANI) nanofibers with nanoparticles (NwN) thin film prepared via iPC-APPJ during various deposition times. (**a**) Top-view of pPANI after 20 min deposition; (**b**)–(**f**) cross-section view of pPANI at various deposition times. Scale bar = 1 \(\upmu\)m.  
Figure 6 shows the Fourier transform infrared spectroscopy (FTIR) spectrum of the pPANI nanofibers and nanoparticles thin film synthesized using the iPC-APPJ technique. As shown in Figure 6, FTIR spectrum was performed using the transmittance method since the pPANI films grown in this experiment were too thin to use the absorbance method. The characteristic peaks of the emeraldine base form of pPANI were observed in the broad peak at 3210 cm\({}^{-1}\) (N-H stretching with hydrogen bonded 2\({}^{\circ}\) amino groups) and 1430 cm\({}^{-1}\) (C-C stretching vibration of benzenoid rings). A peak belonging to the C-H aliphatic vibration was located at 2918 cm\({}^{-1}\). A peak at 1652 cm\({}^{-1}\) was due to the quinonoid structure of pPANI. The out-of-plane C-H ring bending vibration was found in the sharp peak at 891 cm\({}^{-1}\) and 758 cm\({}^{-1}\).