## 3 Results and Discussion
### Characterization and Properties of PEO/Clay Nanocomposites
In the XRD pattern of PEO/5 wt % Cloisite-Na\({}^{+}\) nanocomposite, the diffraction peak related to the basal spacing d\({}_{001}\) was shifted and was observed at 20 = 5.70\({}^{\circ}\) (d\({}_{001}\) = 15.5 A). This increase of the basal spacing is a clear indication that fractions of the PEO chains have been intercalated in the intragallery space between the clay nanolayers [56]. The wide-angle XRD pattern of the pure Cloisite-Na\({}^{+}\) (Figure 4b) exhibits the characteristic peaks of its crystalline structure at \(\sim\)19.8\({}^{\circ}\), 28.2\({}^{\circ}\),  
Figure 3: FTIR spectra of pure PEO, Cloisite-Na\({}^{+}\), and PEO/5 wt % Cloisite-Na\({}^{+}\) (PEO_5 CloisiteNa\({}^{+}\)) nanocomposite. Figure 2: Transparency of films made of pure PEO, drug-loaded (10 wt %) PEO (PEO_10 Aprep), nanocomposites (5 and 10 wt % clay, PEO_5 Cloisite-Na\({}^{+}\) and PEO_10 Closite-Na\({}^{+}\), respectively) and drug-loaded nanocomposites (PEO_10 Aprep_5 Cloisite-Na\({}^{+}\), PEO_10 Aprep_10 Closite-Na\({}^{+}\), respectively). and 35.1\({}^{\circ}\) 20. Similarly, the peaks at 15.98\({}^{\circ}\), 19.9\({}^{\circ}\), 24.14\({}^{\circ}\), 27.02\({}^{\circ}\), 27.80\({}^{\circ}\), and 28.73\({}^{\circ}\) in the pattern of the pure PEO indicate its semicrystalline state. After the melt mixing with the clay, the PEO retained its structure, while the highest intensity peak of the clay at ~19.9\({}^{\circ}\) is superimposed by that of the PEO. The thermal characteristics of the PEO/clay nanocomposites have been extensively discussed in previous studies [57; 58; 59; 60]. DSC analysis is one of the most used methods for analyzing first-order transitions such as melting and crystallization. From the DSC curves presented in Figure 5, the melting point (T\({}_{\rm m}\)) and heat enthalpy of fusion (\(\Delta\)H) of the pure PEO and the PEO/5 wt % clay were determined. The intense peak due to PEO melting appears at 75.89 \({}^{\circ}\)C, indicating the semicrystalline nature of the polymer, while the corresponding peak of the PEO/5 wt % Cloisite-Na\({}^{+}\) nanocomposite has been shifted to a lower temperature (T\({}_{\rm m}\) = 72.83 \({}^{\circ}\)C) along with a decreased endotherm peak area, \(\Delta\)H (\(\Delta\)H\({}_{\rm PEO}\) = 158.161 J/g, \(\Delta\)H\({}_{\rm PEO/5 Cloisite-Na+}\) = 132.647 J/g). This shift to lower T\({}_{\rm m}\) by ca. 3 \({}^{\circ}\)C indicates a slight decrease in the crystallinity of PEO in the nanocomposite, while the decrease of \(\Delta\)H confirms the intercalation of the PEO between clay nanolayers, as indicated above by the XRD results [61]. The decreased heat of fusion (\(\Delta\)H) also indicates that the clay nanolayers may inhibit the crystallization of the PEO matrix. The presence of the nanolayers or even of the finely dispersed clay microparticles in the polymeric matrix disturbs the crystal growth, as the polymer's mobility is decreased due to the presence of these nano-/ microparticles [57; 58; 60]. Figure 4: XRD patterns of PEO and PEO/clay nanocomposites with 5 and 10 wt % clay loading (PEO_5 CloisiteNa\({}^{+}\) and PEO_10 CloisiteNa\({}^{+}\)): (a) low angle range; (b) wide angle range.