## 3 Results and Discussion
### Characterization of Drug-Loaded PEO with 5 and 10 wt % Clay  
The SEM images along with the EDX (Energy Dispersive X-ray) spectra of the APR/PEO/clay formulations are shown in Figures 9 and 10. EDX analysis showed the copresence of both drug (element F) and clay (Al, Si, Na) in the point (microarea) analyzed, thus suggesting the good dispersion and interaction of both components within the PEO matrix. Figure 8: DSC curves of pure aprepitant (APR), pure PEO, and PEO loaded with 5, 10, and 20 wt % of APR (PEO_5 Aprep, PEO_10 Aprep and PEO_20 Aprep, respectively). The FTIR spectra of the APR-loaded PEO/clay nanocomposites are shown in Figure 11 and exhibit similar features to those of the APR/neat PEO spectra shown in Figure 7. More specifically, the peak at 1704 cm\({}^{-1}\) verifies the presence and retention of the structure of APR in the PEO/clay nanocomposites, while the increase of the intensity of the peak at about 1100 cm\({}^{-1}\) is attributed to the presence of Cloisite-Na\({}^{+}\) clay, as also discussed above (Figure 3). Characteristic peaks of APR remained at the same positions, as in the case of neat drug, indicating that no interactions are taking place between the drug and the polymer matrix or clay. The wide-angle XRD patterns of pure aprepitant and PEO, as well as of the PEO/clay nanocomposites and the drug-loaded nanocomposites, are shown in Figure 12. As in the case of the APR/neat PEO blends (Figure 7), the only clearly identifiable peak in the patterns of drug-loaded nanocomposites attributed to APR is the one at about 21.01\({}^{\circ}\), being clearly shown only in the 10 and mainly in the 20 wt % loaded APR. This is an indication that the drug was dispersed in a crystalline state also in both formulations containing clays. However, these peaks, as in the case of PEO/APR solid dispersions, present with lower intensity, indicating a small reduction of its crystallinity. Comparing the formulations between 5 and 10 wt % clay, it can be seen that in the second case, the characteristic peak of APR may exhibit higher intensity, attributed to higher crystallinity of APR. This could be due to the different dispersion of clay inside the polymer matrix, which induces different degree of drug crystallinity. To confirm this, all XRD patterns have been recorded also in lower angles (2-10\({}^{\circ}\)) and are shown in Figure 13.  
Figure 10: SEM image and EDX analysis of drug-loaded PEO nanocomposite with 10 wt % APR and 10 wt % clay (PEO_10 Aprep_10 CloisiteNa\({}^{+}\)). Figure 9: SEM image and EDX analysis of drug-loaded PEO nanocomposites with 5 wt % APR and 5 wt % clay (PEO_5 Aprep_5 CloisiteNa\({}^{+}\)). Figure 11: FTIR spectra of pure APR and the 5, 10, and 20 wt % drug-loaded PEO/clay nanocomposites containing (**a**) 5 wt % clay and (**b**) 10 wt % clay. Figure 12: XRD patterns of pure appointment and PEO, and of the APR-loaded PEO/clay nanocomposites at different drug loadings containing (**a**) 5 wt % and (**b**) 10 wt % clay. The patterns of the APR-loaded PEO/5 wt % clay nanocomposites do not exhibit the d\({}_{001}\) reflection of the clay that is present in the PEO/clay nanocomposite without the drug at about 5.7\({}^{\circ}\) due to the intercalation of the PEO chains, as discussed above (Figure 4). The absence of this reflection implies a highly intercalated or exfoliated clay nanolayer structure within the PEO being induced by the presence of APR. On the other hand, in the patterns of the PEO/10 wt % clay nanocomposites loaded with APR, the d\({}_{001}\) reflection of the clay that appears at about 5.36\({}^{\circ}\) (d\({}_{001}\) = 16.5 A) is partially intercalated compared to the parent Cloisite-Na\({}^{+}\) clay (d\({}_{001}\)= 11.7 A), but not as highly intercalated/exfoliated as in the case of PEO/5 wt % clay nanocomposites loaded with APR. This could justify the different crystallinity of the APR drug in PEO/clay/APR formulations containing different clay contents (5 and 10 wt %).