## 3 Results and Discussion
### FTIR Analysis of CAD + SDS + E-OH Media  
The FTIR analysis was inferred to interpret the possible interactions in an ethanol medium between the cinnamaldehyde (CAD) and sodium dodecyl sulphate (SDS) molecules. The presence of different substitutions with their available surrounding environment between different molecules influences molecular interactions in their aqueous media [33]. Hereby, we determined the possible existing molecular interactions between the CAD \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**(Measured at \(\mathbf{\lambda_{ex}}\) 295 nm)**} & **Below CMC** & **Above CMC** \\ \hline K\({}_{\mathrm{sv}}\) (10\({}^{3}\) M\({}^{-1}\)) & 4.19 & 7.68 \\ \hline K\({}_{\mathrm{q}}\) & \(4.5\times 10^{10}\) & \(3.3\times 10^{15}\) \\ \hline K\({}_{\mathrm{b}}\) (M\({}^{-1}\)) & \(4.51\times 10^{2}\) & \(3.34\times 10^{7}\) \\ \hline n & 1.22 & 4.38 \\ \hline \(\Delta\)G\({}^{\circ}\) (10\({}^{4}\) kJ mol\({}^{-1}\)) & \(-1.51\) & \(-4.30\) \\ \hline \end{tabular}
\end{table} 
Table 2: Stern–Volmer quenching constants (\(K_{\mathrm{sv}}\)), quenching rate constant (\(K_{\mathrm{q}}\)), binding constants (\(K_{\mathrm{b}}\)), number of binding sites (\(n\)), and Gibbs free energy (\(\Delta G^{\circ}\)) for the interaction of cinnamaldehyde (CAD) in SDS-ethanol media at 298.15 K temperature. Figure 6: Stern–Volmer plot of interaction of SDS in the CAD-ethanol system at 298.15 K below CMC. Figure 7: Stern–Volmer plot of interaction of SDS in CAD-ethanol system at 298.15 K above CMC. and SDS as deduced from both the structural information of pure CAD, pure SDS, and varying concentrations of CAD + SDS in an ethanol medium as depicted in Figure 8. Some of the observed essential peak intensities were lower, which confirms the existence of major functional groups of pure cinnamaldehyde. The intensities at 3062.6 cm\({}^{-1}\) and 3026.7 cm\({}^{-1}\) are attributed to presence of -C-H structuring vibrations and aromatic C-H bond structuring vibrations, 2814.5 cm\({}^{-1}\) and 2742.6 cm\({}^{-1}\) are because of -CH\({}_{2}\) structuring vibrations, and the presence of peak intensities within the range of 1648 cm\({}^{-1}\) to 1746 cm\({}^{-1}\), such as 1713.0 cm\({}^{-1}\), 1667.8 cm\({}^{-1}\), and 1619.7 cm\({}^{-1}\) are corresponding -C=O vibrations; the presence of peak intensities between 1463 cm\({}^{-1}\) and 1627 cm\({}^{-1}\), such as 1495.7 cm\({}^{-1}\) and 1574.5 cm\({}^{-1}\), are attributed to aromatic ring -C=C structural structuring vibrations. Meanwhile, C=C of aromatic ring vibrations were observed at 687.5 cm\({}^{-1}\); the presence of these peak intensities is attributed to pure cinnamaldehyde (Figure 6 (b; black line)) [34]. In addition, the major peak intensities as observed at 3324.6 cm\({}^{-1}\), 2971.6 cm\({}^{-1}\), 2926.4 cm\({}^{-1}\), 2881.2 cm\({}^{-1}\), 1085.8 cm\({}^{-1}\), and 1015.2 cm\({}^{1}\), respectively were observed in the pure spectrum of SDS molecules as depicted in Figure 6 (c; red line). Observed peak intensity at 3324.6 cm\({}^{-1}\) was assigned to the -O-H structuring vibrations modes, 2971.6, 2926.4, and 2881.2 cm\({}^{-1}\), which are attributed to the presence of asymmetric and symmetric structuring vibration modes of C-H aliphatic carbon chains [35]. In addition, the observed peak intensities at 1085.8 and 1015.2 cm\({}^{-1}\) are assigned to the corresponding S-O and S=O structuring vibrational modes respectively [36; 37]. Based on the pre- and post-micellization concentrations of the FTIR analysis of combined CAD + SDS in ethanol solution as depicted in Figure 6 (F; cyan line and G; pink line), we observed the disappearance of CAD peak intensity at 1667.6 cm\({}^{-1}\) (i.e., presence of -C=O vibrations), and also the observed lengthening of -O-H structuring vibrations at 3324.6 cm\({}^{-1}\) towards the higher frequency, i.e., 3327.0 cm\({}^{-1}\) in mixed CAD + SDS, emphasizing the possible hydrogen bond interaction in the mixed ethanol medium.