## 2 Results and Discussion
### Characteristics of Synthesized REEIIPs and Hybrid Materials
In addition, for both types of membranes, an increase in the values of the mechanical parameters was noted with an increase in the modified MWCNT addition, which might indicate good dispersion of the inorganic particles in the polymer matrix and appropriate interaction of the modified nanoparticles with the matrix based on the same IIPs. In the case of Nd-selective membranes, an increase in Rm by about 80%, E modulus by about 150%, and an almost 4-fold increase in elongation at break was noted, which indicated improved flexibility and toughness. In contrast, for Gd-selective membranes, the increase in Rm was almost 2.5-fold, 2-fold for Young's modulus, and 60% increase for elongation at break. Higher values of Young's modulus in the case of GdIIP hybrid membranes may be related to a higher final addition of modified MWCNTs (5 wt.%). An interesting observation was the gradual increase in E and Rm modulus in the case of NdIIP hybrid membranes, with the MWCNT addition and the rapid increase in the case of the GdIIP hybrid membranes with  
Figure 4: Variation in (a) storage modulus E\({}^{\prime}\), (b) loss modulus E\({}^{\prime\prime}\), and (c) loss factor tan \(\delta\) as a function of the temperature for Pr sensitive membranes with various modified MWCNT-PrIIP additions. both types of membranes reaching similar values of the two mechanical parameters. The elongation at break value was almost 2 or even 3-fold lower for membranes based on GdIIPs. The observed differences may result from significant differences in the functionalization of MWCNTs with ionically imprinted polymers, wherein in the case of Gd the degree of functionalization was only 12%, while for Nd it was 29%. This may be related to the lower compatibility of MWCNT-GdIIP nanotubes with the polymer matrix, which may directly affect the lower values of elongation at break. It should also be noted that the use of an external magnetic field during membrane production had a positive effect on the dispersion of MWCNTs in polymer matrices, as well as on their mechanical properties. The improvement in mechanical properties may result from the increase in the density of the membrane material and the reduction in the mobility of polymer chains with the increase in the filler addition. Some of the newly developed hybrid membranes were also analyzed using X-ray micro-tomography. The presence of several phases can be seen in the X-ray tomography images (Figure 6). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Membrane**} & \multirow{2}{*}{**R\({}_{\text{m}}\) [MPa]**} & \multicolumn{2}{c}{**Young’s Modulus**} & \multirow{2}{*}{**Elongation at Break [\%]**} \\  & & & **E [MPa]** \\ \hline Nd sensitive membrane & 36.72 \(\pm\) 1.84 & 128.9 \(\pm\) 6.3 & 6.68 \(\pm\) 0.88 \\ Nd sensitive hybrid membrane with 2 wt.\% MWCNT-NdIIPs & 49.80 \(\pm\) 2.50 & 152.2 \(\pm\) 7.4 & 20.68 \(\pm\) 2.71 \\ Nd sensitive hybrid membrane with 3 wt.\% MWCNT-NdIIPs & 58.03 \(\pm\) 3.21 & 191.2 \(\pm\) 9.3 & 21.63 \(\pm\) 2.84 \\ Nd sensitive hybrid membrane with 4 wt.\% MWCNT-NdIIPs & 67.37 \(\pm\) 3.38 & 213.5 \(\pm\) 10.4 & 33.30 \(\pm\) 4.37 \\ Gd sensitive membrane & 30.55 \(\pm\) 1.71 & 116.2 \(\pm\) 7.4 & 7.93 \(\pm\) 0.98 \\ Gd sensitive hybrid membrane with 0.5 wt.\% MWCNT-GdIIPs & 62.37 \(\pm\) 3.49 & 203.2 \(\pm\) 9.9 & 8.37 \(\pm\) 1.04 \\ Gd sensitive hybrid membrane with 1 wt.\% MWCNT-GdIIPs & 69.88 \(\pm\) 3.91 & 243.5 \(\pm\) 15.6 & 10.44 \(\pm\) 1.29 \\ Gd sensitive hybrid membrane with 2 wt.\% MWCNT-GdIIPs & 70.68 \(\pm\) 3.96 & 246.9 \(\pm\) 15.8 & 12.91 \(\pm\) 1.60 \\ Gd sensitive hybrid membrane with 5 wt.\% MWCNT-GdIIPs & 76.06 \(\pm\) 4.26 & 249.8 \(\pm\) 16.0 & 13.01 \(\pm\) 1.61 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mechanical properties of the newly developed membranes.