## 2 Results and Discussion
### Effect of Composition of Copolymer Catalysts on Activity in Aerobic Oxidation of PMT
It can be concluded that after exceeding the critical NHPI and DVB contents, defined by the observed diagonal, the activity of the developed copolymer catalysts drops sharply. Certainly, the observed effect is not only related to the NHPI content as confirmed by the results of the CHN analyzes. Table 2 exhibits the N content in the synthesized materials expressed in mmol in relation to 1 g of a copolymer. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mol\% of DVB**} & \multicolumn{8}{c}{**mol\% of NHPI**} \\ \cline{2-10}  & **10** & **20** & **30** & **40** & **50** & **60** & **70** & **80** & **90** \\ \hline \multirow{2}{*}{1} & 14.4 & 7.4 & 9.7 & 16.4 & 4.4 & 10.8 & 3.1 & 0.7 & 3.1 \\  & (2.31) & (1.24) & (1.56) & (2.64) & (0.71) & (1.74) & (0.49) & (0.11) & (0.50) \\ \hline \multirow{2}{*}{3} & 9.9 & 17.6 & 16.3 & 19.3 & 15.1 & 17.5 & 2.7 & 6.5 & 2.3 \\  & (1.59) & (2.83) & (2.62) & (3.11) & (2.44) & (2.82) & (0.43) & (1.05) & (0.37) \\ \hline \multirow{2}{*}{5} & 9.8 & 18.0 & 18.5 & 15.6 & 18.4 & 23.3 & 2.1 & 1.4 & 1.0 \\  & (1.58) & (2.90) & (2.98) & (2.52) & (2.96) & (3.75) & (0.34) & (0.23) & (0.16) \\ \hline \multirow{2}{*}{7} & 14.9 & 19.5 & 23.6 & 21.6 & 21.5 & 10.0 & 4.5 & 3.8 & 2.0 \\  & (2.40) & (3.14) & (3.81) & (3.48) & (3.47) & (1.61) & (0.73) & (0.62) & (0.32) \\ \hline \multirow{2}{*}{9} & 14.1 & 17.9 & 22.0 & 7.3 & 5.8 & 5.2 & 7.6 & 2.9 & 2.2 \\  & (2.27) & (2.88) & (3.54) & (1.18) & (0.93) & (0.84) & (1.22) & (0.46) & (0.36) \\ \hline \multirow{2}{*}{11} & 10.2 & 5.0 & 16.6 & 13.4 & 6.5 & & & & \\  & (1.64) & (0.81) & (2.68) & (2.15) & (1.05) & n.m. & n.m. & n.m. & n.m. \\ \hline \hline \end{tabular} The most active samples are highlighted by shading background, n.m.—not measured.  
\end{table} 
Table 1: Conversion of PMT (%) and consumption of O\({}_{2}\) (mmol, values given in brackets) in the presence of the copolymer catalysts with different NHPI loadings and cross-linking degrees measured after 6 h tests at 80 \({}^{\circ}\)C (0.1 g copolymer catalyst, 5.0 mg AlBN, 5.0 mg Co(OAc)\({}_{2}\) 4H\({}_{2}\)O, 2.0 mL PMT, 1 atm O\({}_{2}\)). It can be clearly seen that, as predicted, the N content rises within the series with the increase in the amount of the NHPI monomer used in the synthesis. The experimental values confirm quite good agreement with the assumed ones. The highest amount of nitrogen incorporated into the copolymer structure (achieved for the 80%NHPI_1%DVB catalyst) is 6.46 mmol/g, which corresponds to 9.1 wt%. A key parameter determining the activity of the studied catalysts must therefore be the availability of N-OH functionalities which are partially closed within the copolymer structure. These sites can be activated during the reaction, when the material swells in the presence of organic substrate. The pseudoporous structure created in this way enables relatively easy diffusion of reagent molecules to active centers. To determine the susceptibility of the studied copolymers to the formation of such structures, we studied the swelling capacity of the samples using chloroform as the solvent. Figure 2 demonstrates the determined values of swelling degree (S\({}_{\text{e}}\)) for two selected series of catalysts--30%NHPI_xDVB and xNHPI_9%DVB. It can be seen that fairly small, non-polar chloroform molecules easily penetrate the copolymer structure, the swelling capacity of which is strongly depended on the cross-linking degree. For the 30%NHPI_xDVB series this expected effect results in a change in the value of S\({}_{\text{e}}\) from 6.4 (lower cross-linking degree) to 3.9 (higher cross-linking degree). However, the collected data reveal one more correlation, namely the decrease in the S