## 3 Results and Discussion
### Characterisation of the Protective Polymer Formulations and Study of the Interactions  
**Fluoline HY. **\({}^{19}\)F MAS NMR, \({}^{13}\)C (\({}^{19}\)F) CP-MAS NMR and \({}^{13}\)C (\({}^{1}\)H) CP-MAS NMR spectra of Fluoline HY film together with the chemical shift assignment are reported in Figures 5-8 and in Tables 1-3. Figure 8: \({}^{13}\)C[\({}^{1}\)H] CP-MAS NMR spectrum of Fluoline HY film. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Peak** &
\begin{tabular}{c} **Chemicals Shift** \\ **(Ppm)** \\ \end{tabular} & **Assignment** & **Monomeric Unit** \\ \hline
1 & \(-\)73.22 & \(-\)(CF\({}_{2}\))\({}_{2}\)\(-\)CF(CF\({}_{3}\))\(-\) & HFP \\
2 & \(-\)88.67 & \(-\)CH\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CH\({}_{2}\)\(-\) & VDF \\
3 & \(-\)108.96 & \(-\)CH\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CH\({}_{2}\)\(-\) & VDF \\
4 & \(-\)116.10 & \(-\)CH\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CF(CF\({}_{3}\))\(-\) & HFP \\
5 & \(-\)181.59 & \(-\)(CF\({}_{2}\))\({}_{2}\)\(-\)CF(CF\({}_{3}\))\(-\) & HFP \\ \hline \hline \end{tabular} The assignment of the resonances in the \({}^{19}\)F MAS spectrum was performed according to the literature [31]. The signals at \(-\)73.22 ppm are due to the HFP units for the side \(-\)CF\({}_{3}\) (\(-\)CF\({}_{2}\)\(-\)CF(**CF\({}_{3}\)**)\(-\)), and those at \(-\)116.10 ppm are due to the \(-\)CF\({}_{2}\) group directly linked to the \(-\)CF\({}_{2}\) of the VDF (\(-\)CF\({}_{2}\)\(-\)CF\({}_{2}\)CF (CF\({}_{3}\)**)\(-\)). The signal at \(-\)181.59 ppm is due to the \(-\)CF (\(-\)CF\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CH\({}_{2}\)\(-\)) group. Finally, the signals at \(-\)88.67 and \(-\)108.86 ppm were assigned to the VDF units resulting from head-to-tail (\(-\)CH\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CH\({}_{2}\)\(-\)) and head-to-head additions (\(-\)CH\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CF\({}_{2}\)\(-\)CH\({}_{2}\)\(-\)), respectively.  
\end{table} 
Table 1: Chemical shift assignment of the of \({}^{19}\)F MAS NMR spectrum. Figure 7: Sequence of repetitive units in Fluoline HY. In the \({}^{13}\)C [\({}^{19}\)F] CP-MAS spectrum, it is worth noting that the intensity of peak 3 due to CF\({}_{2}\) groups is lower than the one of peak 4 due to CF. This is because the \(-\)CF\({}_{2}\) group in (\(-\)CH\({}_{2}-\)CF\({}_{2}-\)CH\({}_{2}-\)) units receives magnetization only from the two \({}^{19}\)F nuclei directly bonded to it and the \(-\)CF group in (\(-\)CF\(-\)CF\({}_{3}\)) units receives magnetization both from the \({}^{19}\)F atom directly bound to it and from the adjacent \(-\)CF\({}_{3}\) group, as the cross-polarization mechanism involves dipolar interactions occurring through space. This finding and the analysis of the peaks confirmed that the sequence of repetitive units of the Fluoline HY is that shown in Figure 7.  
In the \({}^{13}\)C [\({}^{1}\)H] CP\(-\)MAS spectrum (Figure 8), the resonances of the \(-\)CH\({}_{2}\) signal groups at 44.08 assigned to the VDF units for the head (CH\({}_{2}\)) to tail (CF\({}_{2}\)) additions (\(-\)CF\({}_{2}-\)CH\({}_{2}-\)CF\({}_{2}-\)CH\({}_{2}-\)) and the resonances at 118.86 ppm that correspond to sp\({}^{2}\) hybridized carbons or fluorinated hydrocarbons are present [32]. **FLUO AQ. **\({}^{19}\)F MAS NMR, \({}^{13}\)C [\({}^{19}\)F] CP\(-\)MAS NMR and \({}^{13}\)C [\({}^{1}\)H] CP\(-\)MAS NMR spectra of the Fluo AQ film and the chemical shift assignment are reported in Figures 9-11 and in Tables 4-6. Figure 11: \({}^{13}\)C[\({}^{1}\)H] CP\(-\)MAS NMR spectrum of Fluo AQ film. \begin{table}
\begin{tabular}{c c c} \hline
**Peak** & **Chemicals Shift (Ppm)** & **Assignment** \\ \hline
1 & \(-\)79.37 & \(-\)CF\({}_{2}-\)CF\({}_{2}-\)CF\({}_{3}\) \\
2 & \(-\)111.02 & \(-\)CH\({}_{2}-\)CF\({}_{2}-\)CF\({}_{2}-\) \\
3 & \(-\)120.62 & \(-\)CF\({}_{2}-\)CF\({}_{2}-\)CF\({}_{2}-\) \\
4 & \(-\)123.96 & \(-\)CF\({}_{2}-\)CF\({}_{2}-\)CF\({}_{3}\) \\ \hline \end{tabular}
\end{table} 
Table 4: Assignment of the chemical shift \({}^{19}\)F MAS NMR spectrum.