## 4 Results and Discussion  
### Morphological Analyses of the Plasma-Treated SiO\({}_{2}\) Nanofilers  
The morphological analysis of the SiO\({}_{2}\) nanoparticles before and after chemical modification using silane coupling and electrical treatment using atmospheric-pressure plasma discharges were characterized using FESEM and EDX. In addition, XPS analysis was conducted to observe the atomic concentration and binding energy of the nanoparticles. The overall XPS showed that the nanoparticles contained C 1s, O 1s, and Si 2p peaks. The XPS spectra of the untreated, silane-treated, and plasma-treated nanoparticles are shown in Figure 4. We can see that the Si 2p spectrum has shifted from a higher binding energy (BE) of the untreated nanoparticles to a lower BE after the silane and plasma treatments. For the silane-treated nanoparticles the shift in BE was significant, while for the plasma-treated nanoparticles the shift was slight (in fact, insignificant). From Figure 4, we can also see the intensity of the Si-O bonds. The intensity increased in the plasma-treated nanoparticles, while it decreased in the silane-treated particles. The discharge at atmospheric pressure involves oxygen atoms, which tend to become attached to Si and C atoms. The increase in the intensity of the Si-O bond after plasma treatment implies that a reaction of the oxygen atoms with the Si atoms took place during the plasma-treatment process. Table 1 shows the binding energy and concentrations of the nanoparticles. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Untreated**} & \multicolumn{2}{c}{**Silane-Treated**} & \multicolumn{2}{c}{**Plasma-Treated**} \\ \hline
**BE (eV)** & **Intensity** & **BE (eV)** & **Concentration (\%)** & **BE (eV)** & **Concentration (\%)** \\ \hline
101.79 & 2500 & 101.70 & 2230 & 101.70 & 3040 \\
104.79 & 655 & 103.80 & 551 & 104.68 & 545 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Si 2p binding energy and concentration of untreated, silane-treated, and plasma-treated nanoparticles. Figure 4: Surface composition of nanoparticles: untreated, silane-treated, and plasma-treated. The SiO\({}_{2}\) nanoparticles consisted of Si-O and Si-C bonds for the untreated, silane-treated, and plasma-treated nanoparticles as shown in Table 1. The plasma discharge contained many active species that led to the formation of radicals. The recombination of radicals also resulted in a reduction of the surface-charging effect of the nanoparticles. As a result, this reduction led to a shift to lower BE; the lower BE was a result of the addition of oxidized atoms that increased the interaction when mixed with the polymer base. The plasma discharges also resulted in surface oxidation due to the oxygen atoms' attachment to the C and Si atoms within the nanoparticles. Further O atoms attaching to Si atoms resulted in an increase in the concentration of Si-O bonds [17]. Figure 5 shows FESEM micrographs of the nanoparticles before and after the treatment. We can see that the untreated nanoparticles are porous, with an irregular surface structure. This type of structure led to the accumulation and trapping of static charges, thus resulting in agglomeration; the particles were attracted to one another via static charges on the particles' surfaces. Figure 5b,c show the FESEM images of the silane-treated and plasma-treated nanosilica (SiO\({}_{2}\)), respectively. From the figures, we can see that both the silane-treated and plasma-treated nanoparticles had relatively smoother and more homogenous surfaces compared to the untreated samples. Compared to the silane-treated nanoparticles, the plasma-treated nanoparticles seem to have had a more uniform, smoother surface due to the plasma coating of the nanoparticles' surfaces, with less nanoparticle accumulation. The plasma treatment of the nanoparticles affected the surface of the nanoparticles. The plasma treatment enhanced surface compatibility, reduced agglomeration, altered the interfaces, and increased the surface area of the nanoparticles.