# Assessment of Catalyst Selectivity in Carbon-Nanotube Silylesterification
## 3 Results
### Silylesterification  
Table 6 and Figure 6 summarize the atomic percentages of various elements in 12 samples produced by the derivatization of six types of diazonium-modified CNTs using either zinc chloride or [PERSON]'s catalyst. Figure 7 displays XPS comparisons of the samples' survey spectra after derivatization with diazonium and silylesterification with either zinc chloride or [PERSON]'s catalyst. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Samples** & **Catalyst** & **C \%** & **O \%** & **N \%** & **F \%** & **Si \%** & **Pt \%** & **Zn \%** \\ \hline \multirow{2}{*}{CNT-COOH} & ZnCl\({}_{2}\) & 91.0 \(\pm\) 0.4 & 7.3 \(\pm\) 0.1 & 0.4 \(\pm\) 0.4 & **0.0** & 0.0 & - & 1.2 \(\pm\) 0.1 \\  & [PERSON]’s catalyst & 84.3 \(\pm\) 0.2 & 6.4 \(\pm\) 0.3 & 1.4 \(\pm\) 0.1 & **5.7 \(\pm\) 0.7** & 1.1 \(\pm\) 0.1 & 0.7 \(\pm\) 0.1 & - \\ \hline \multirow{2}{*}{CNT-CH\({}_{2}\)-COOH} & ZnCl\({}_{2}\) & 87.2 \(\pm\) 0.6 & 6.2 \(\pm\) 0.3 & 4.1 \(\pm\) 0.3 & **2.4 \(\pm\) 0.1** & 0.5 \(\pm\) 0.1 & - & 0.6 \(\pm\) 0.1 \\  & [PERSON]’s catalyst & 81.9 \(\pm\) 0.9 & 7.4 \(\pm\) 0.3 & 6.3 \(\pm\) 0.4 & **3.0 \(\pm\) 0.8** & 0.8 \(\pm\) 0.2 & 0.5 \(\pm\) 0.1 & - \\ \hline \multirow{2}{*}{CNT-OH} & ZnCl\({}_{2}\) & 94.3 \(\pm\) 0.7 & 4.8 \(\pm\) 0.1 & 0.2 \(\pm\) 0.2 & **0.6 \(\pm\) 0.4** & 0.0 & - & 0.0 \\  & [PERSON]’s catalyst & 85.7 \(\pm\) 3.2 & 8.9 \(\pm\) 3.3 & 0.4 \(\pm\) 0.1 & **3.1 \(\pm\) 0.6** & 1.3 \(\pm\) 0.1 & 0.5 \(\pm\) 0.1 & - \\ \hline \multirow{2}{*}{CNT-CH\({}_{2}\)-OH} & ZnCl\({}_{2}\) & 89.8 \(\pm\) 1.1 & 7.2 \(\pm\) 0.5 & 2.2 \(\pm\) 0.1 & **0.0** & 1.5 \(\pm\) 0.1 & - & 0.0 \\  & [PERSON]’s catalyst & 85.5 \(\pm\) 0.2 & 6.1 \(\pm\) 0.2 & 2.4 \(\pm\) 0.2 & **3.9 \(\pm\) 0.2** & 1.9 \(\pm\) 0.2 & 0.2 \(\pm\) 0.2 & - \\ \hline \multirow{2}{*}{CNT-C(O)-CH\({}_{3}\)} & ZnCl\({}_{2}\) & 93.6 \(\pm\) 0.5 & 5.0 \(\pm\) 0.1 & 1.2 \(\pm\) 0.4 & **0.1 \(\pm\) 0.1** & 0.0 & - & 0.0 \\  & Karstedt’s catalyst & 89.3 \(\pm\) 0.5 & 5.6 \(\pm\) 0.1 & 1.6 \(\pm\) 0.3 & **1.5 \(\pm\) 0.3** & 1.8 \(\pm\) 0.1 & 0.1 \(\pm\) 0.1 & - \\ \hline \multirow{2}{*}{CNT-O-CH\({}_{3}\)} & ZnCl\({}_{2}\) & 91.4 \(\pm\) 0.5 & 5.6 \(\pm\) 0.3 & 1.5 \(\pm\) 0.2 & **0.8 \(\pm\) 0.1** & 0.6 \(\pm\) 0.1 & - & 0.0 \\  & [PERSON]’s catalyst & 91.3 \(\pm\) 0.5 & 5.3 \(\pm\) 0.3 & 0.8 \(\pm\) 0.8 & **1.7 \(\pm\) 0.3** & 0.9 \(\pm\) 0.1 & 0.0 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Atomic % of various elements in six samples of diazonium-modified CNTs that were silylesterified with either zinc chloride or Karstedt’s catalyst. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Functional Group** & **Molecule** & \(\delta_{\text{d}}\) **(MPa\({}^{1/2}\))** & \(\delta_{\text{p}}\) **(MPa\({}^{1/2}\))** & \(\delta_{\text{h}}\) **(MPa\({}^{1/2}\))** \\ \hline \multirow{3}{*}{Ketone} & Acetone & 15.5 & 10.4 & 7.0 \\  & 2-Butanone & 16.0 & 9.0 & 5.1 \\  & Acetophenone & 19.6 & 8.6 & 3.7 \\ \hline \multirow{3}{*}{Ether} & Diethylether & 14.5 & 2.9 & 5.1 \\  & Dipropylene & 15.2 & 3.4 & 4.2 \\  & Anisole & 17.8 & 4.1 & 6.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Hansen solubility parameters for molecular characteristics of ethers and ketones. Values compared to those in Table 4.  
Figure 6: Changes in fluorine quantity as function of oxygenated functional group grafted by diazonium chemistry and catalyst used for silylesterification. Figure 7: Comparison of XPS survey spectra for six diazonium-modified samples before and after silylesterification using zinc chloride or [PERSON]’s catalyst. The observed fluorine percentages (in bold) showed two extremely different types of behavior depending on the used catalyst. [PERSON]'s catalyst allowed for the silylesterification of all oxygenated functional groups. The process was more efficient for carboxyls and alcohols, regardless of whether they contained an aromatic ring [24; 25]. Zinc chloride catalyzed the silylesterification of only nonaromatic carboxylic acids.