## 2 Results and Discussion
### Characteristics of Synthesized REEIIPs and Hybrid Materials
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Membrane**} & **Coercivity** & \multicolumn{2}{c}{**Saturation**} & **Remanence** \\  & **Hc [Oe]** & **Magnetization,** & **[emu/g]** \\ \hline Modified chitosan & 549.0 \(\pm\) 27.9 & 0.085 \(\pm\) 0.008 & 0.020 \(\pm\) 0.001 \\ \hline Modified chitosan imprinted with Nd & 736.4 \(\pm\) 37.4 & 0.094 \(\pm\) 0.009 & 0.010 \(\pm\) 0.001 \\ \hline Modified chitosan imprinted with Pr & 322.7 \(\pm\) 16.4 & 0.157 \(\pm\) 0.014 & 0.010 \(\pm\) 0.001 \\ \hline Modified chitosan imprinted with Gd & 804.5 \(\pm\) 40.8 & 0.044 \(\pm\) 0.004 & 0.010 \(\pm\) 0.001 \\ \hline NdIIPs & 781.8 \(\pm\) 39.7 & 0.076 \(\pm\) 0.007 & 0.020 \(\pm\) 0.002 \\ \hline PrIIPs & 895.4 \(\pm\) 45.5 & 0.078 \(\pm\) 0.007 & 0.020 \(\pm\) 0.002 \\ \hline GdIIPs & 818.2 \(\pm\) 41.5 & 0.075 \(\pm\) 0.007 & 0.020 \(\pm\) 0.002 \\ \hline Nd sensitive hybrid membrane with 1 wt.% MWCNT-NdIIPs & 133.09 \(\pm\) 6.76 & 0.242 \(\pm\) 0.022 & 0.003 \(\pm\) 0.001 \\ \hline Nd sensitive hybrid membrane with 2 wt.% MWCNT-NdIIPs & 126.62 \(\pm\) 6.43 & 0.299 \(\pm\) 0.028 & 0.003 \(\pm\) 0.001 \\ \hline Nd sensitive hybrid membrane with 3 wt.% MWCNT-NdIIPs & 65.75 \(\pm\) 3.34 & 0.259 \(\pm\) 0.024 & 0.002 \(\pm\) 0.001 \\ \hline Nd sensitive hybrid membrane with 4 wt.% MWCNT-NdIIPs & 48.87 \(\pm\) 2.48 & 0.442 \(\pm\) 0.041 & 0.009 \(\pm\) 0.001 \\ \hline Pr sensitive polymer membrane & 765.23 \(\pm\) 38.85 & 0.079 \(\pm\) 0.007 & 0.006 \(\pm\) 0.001 \\ \hline Pr sensitive hybrid membrane with 0.5 wt.% MWCNT-PrIIPs & 125.11 \(\pm\) 6.35 & 0.236 \(\pm\) 0.022 & 0.004 \(\pm\) 0.001 \\ \hline Pr sensitive hybrid membrane with 1 wt.% MWCNT-PrIIPs & 60.46 \(\pm\) 3.07 & 0.286 \(\pm\) 0.026 & 0.003 \(\pm\) 0.001 \\ \hline Pr sensitive hybrid membrane with 2 wt.% MWCNT-PrIIPs & 58.09 \(\pm\) 2.95 & 0.288 \(\pm\) 0.027 & 0.003 \(\pm\) 0.001 \\ \hline Pr sensitive hybrid membrane with 5 wt.% MWCNT-PrIIPs & 52.58 \(\pm\) 2.67 & 0.329 \(\pm\) 0.030 & 0.002 \(\pm\) 0.001 \\ \hline Gd sensitive polymer membrane & 811.61 \(\pm\) 41.20 & 0.092 \(\pm\) 0.008 & 0.008 \(\pm\) 0.001 \\ \hline Gd sensitive hybrid membrane with 0.5 wt.% MWCNT-GdIIPs & 808.92 \(\pm\) 41.06 & 0.073 \(\pm\) 0.007 & 0.010 \(\pm\) 0.001 \\ \hline Gd sensitive hybrid membrane with 1 wt.% MWCNT-GdIIPs & 155.10 \(\pm\) 7.87 & 0.274 \(\pm\) 0.025 & 0.007 \(\pm\) 0.001 \\ \hline Gd sensitive hybrid membrane with 2 wt.% MWCNT-GdIIPs & 40.27 \(\pm\) 2.04 & 0.301 \(\pm\) 0.028 & 0.005 \(\pm\) 0.001 \\ \hline Gd sensitive hybrid membrane with 5 wt.% MWCNT-GdIIPs & 22.86 \(\pm\) 1.16 & 0.303 \(\pm\) 0.028 & 0.005 \(\pm\) 0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Magnetic properties of synthesized polymers and Gd, Nd, and Pr sensitive membranes. in the value of this parameter was noted with the rising addition of modified MWCNTs: 3-fold for the Gd-sensitive, 4-fold for Pr-sensitive, and even 10-fold for the Nd-sensitive hybrid membranes with the highest filler content (Figure 8c,d). Comparing the hysteresis loops of hybrid membranes with 2 wt.% addition of modified nanotubes (Figure 8f) showed that their shape was similar. The magnetization values of the Pr- and Gd-selective hybrid membranes were very similar (over 0.3 emu/g), while that of the Nd-selective membrane was much higher (over 0.44 emu/g). This was reflected in the magnetic properties of the hybrid membranes based on these polymer matrices, indicating enhanced magnetic response via MWCNT incorporation. The value of the remanence (Table 2) remaining low across all samples (consistent with weak ferromagnetic behavior) slightly changed with an increase in the filler addition. On the other hand, the polymer membranes showed similar values of coercivity (765-850 Oe). Only the introduction of modified MWCNTs into the polymer matrix resulted in a decrease in the value of coercivity, which might be associated with creation in the outer magnetic field of more developed 3D structures in a polymer matrix.