## 3 Results and Discussion  
### Coatings Nanostructure  
X-ray diffraction has been widely employed for the characterization of polymer-layered silicate (PLS) nanocomposites [35]. In fact, the gap between the silicate layers (\(d\)), called \"interlayer\" or \"gallery\", can be determined according to the Bragg's law:  
\[sin\theta=\frac{n\lambda}{2d}, \tag{4}\]  
where \(\theta\) is the diffraction angle measured, and \(\lambda\) corresponds to the wave length of the X-ray radiation used in the diffraction experiment [59]. Therefore, the X-ray diffractogram of the nanoclay polymer can be used to determinate if an intercalated or exfoliated nanostructure has been obtained. In the first case, the polymeric chains must intercalate between the silicate platelets causing an increase of the interlayer spacing. Therefore, the diffraction peaks obtained for an intercalated nanoclay polymer shifts towards lower angle compared to the XRD patterns of the pure nanoclay powder. In case of an exfoliated PLS nanocomposite, the ordered structure of the nanoclay is lost, so that no more diffraction peaks are visible in the XRD diffractograms. Figure 3 shows the diffractograms of the as received Cloisite(r)Na\({}^{+}\) powder, a nanoclay film obtained by drying the aqueous nanoclay dispersion (MMTD) at 110 \({}^{\circ}\)C (Figure 3b), and polymeric films of the SB-MMT (Figure 3c), as well as CSB-MMT (Figure 3d). The layers spacing calculated from the diffraction peak of the as received Cloisite(r)Na\({}^{+}\) is equal to 1.21 nm, which is in accordance with the information reported from the producer. It can be observed that the diffraction peak of the nanoclay film obtained form the MMTD is shifted towards lower angle compared to the XRD patterns of the as delivered Cloisite(r)Na\({}^{+}\) powder. This suggests that the distance between the layered silicates has been increased. Montmorillonite, as other smectite clay, is reported to adsorb water molecules and form stable aqueous dispersion where the interlayer spacing can increase up to 4 nm for high water content [60]. By successively drying the dispersion, the silicate interlayer spacing falls back to smaller distance value. However, Na\({}^{+}\) cations in the silicate gallery are reported to form hydrated complex with strongly bonded water molecules [61]. Therefore, it can be supposed that the shift of the diffraction angle observed for the Cloisite(r)Na\({}^{+}\) after dis persion in distilled water is due to the hydration of the montmorillonite interlayer cations. Figure 3 shows that the diffraction peaks of the SB-MMT and CSB-MMT film are further shifted to smaller angles, with a corresponding \(d\) value of 1.46 nm. The diffraction angles observed for sample SB-MMT and CSB-MMT indicate a greater separation of the silicate layers. However, the obtained space gallery is comparable with the intercalation of small molecules, such as alkylammonium ions or organosilane molecules [62; 63], rather than polymeric chains [64; 65]. Since surfactants are commonly employed for the production of polymeric latex, the observed increase in the diffraction angles can also be attributed to the intercalation of organic ions between the silicate layers. This mechanism would reassemble the intercalation of alkylammonium ions typically employed for the functionalization of layerde silicates with organic moieties [35]. Therefore, according to the results obtained, the formation of a nanostructured polymer cannot be confirmed. The flatter shape of the CSB-MMT diffraction peak (Figure 3d) can be attributed to a lower signal intensity due to the formation of many air bubbles in the polymeric film, as can be observed from Figure 4c. Although XRD offers a conventional method for the determination of the nanocomposite interlayer structure, it does not give any information about the spatial distribution of the silicate in the matrix or the formation of inhomogeneities in the PLS nanocomposite.