## 3 Results and Discussion
### Characterization of Magnetic PMO Nanoparticle Systems
The organic contents of the magnetic PMO nanoparticles were tested by thermogravimetric analysis (TGA). In both systems, slight decomposition occurred in the temperature range of 50-100 \({}^{\circ}\)C, which could have resulted from ethanol and water residues in the detected system, whereas a major decomposition process occurred between 200 and 650 \({}^{\circ}\)C. This confirms the good thermal stability of the synthesized magnetic PMO nanoparticles compared with the oleic acid-coated MNPs. Figure 9 shows curve a, in which a total weight loss of 13.47% was detected for MNP-OA, whereas M-Ethylene PMO NPs afforded a total organic loss of 23.7% (Figure 9, curve b) compared to 37.4% for M-Phenylene PMO NPs (Figure 9, curve c). The PMO NPs' chemical properties were further characterized by solid-state \({}^{29}\)Si and \({}^{13}\)C CP-MAS NMR spectroscopy. The solid-state NMR results of these magnetic systems were recorded after treatment with concentrated HCl to remove the magnetic cores. The \({}^{29}\)Si NMR spectrum of M-Ethylene PMO NPs (Figure 10a) exhibits a major T\({}^{3}\) signal at \(-65\) ppm, which can be assigned to organosilica species. Similar results were observed in the \({}^{29}\)Si NMR spectrum of M-Phenylene PMO NPs (Figure 10c), which exhibited three T signals at \(-58\), \(-71\), and \(-80\) ppm. The observed signals are assigned to the T\({}^{2}\) and T\({}^{3}\) groups in the resulting organosilica network. These observations clearly demonstrate the formation of Si-C covalent bonds in both magnetic PMO NP systems. In addition, the \({}^{13}\)C NMR spectrum of the M-Ethylene PMO NPs in Figure 10b shows the chemical composition of the ethylene-bridged nanoparticles with a major peak around 8-10 ppm, which belongs to the SiCH  
Figure 8: IR spectra of (**a**) M-Ethylene PMO NPs and (**b**) M-Phenylene PMO NPs. Figure 7: XRD pattern of (**a**) M-Ethylene PMO NPs and (**b**) M-Phenylene PMO NPs. groups. Two minor peaks of unhydrolyzed ethoxy groups at 13 ppm and 56 were also observed in the \({}^{13}\)C NMR spectrum. In Figure 10d, the \({}^{13}\)C NMR spectrum of M-Phenylene PMO NPs also confirms the presence of the aromatic c groups that clearly appear at a range of 128-147 ppm. In addition, in this spectrum, unhydrolyzed ethoxy groups were detected. These results clearly indicate the formation of silsesquioxane frameworks and further demonstrate the incorporation of organic units into the silica networks. Figure 10: \({}^{29}\)Si and \({}^{13}\)C CP-MAS of M-Ethylene PMO-NPs (**a**,**b**) and M-Phenylene PMO NPs (**c**,**d**). Figure 9: Thermogravimetric analysis (TGA) curves of (**a**) MNP-OA, (**b**) Magnetic Ethylene-PMO NPs, and (**c**) Magnetic Phenylene-PMO NPs. The N\({}_{2}\) adsorption-desorption of M-Ethylene PMO NPs and M-Phenylene PMO NPs provides further evidence of the special porosity character of the obtained magnetic nanosystems. As observed in Figure 11, characteristic IV-type isotherms with a narrow pore size distribution for both magnetic PMO nanoparticles were obtained. The BET surface area of Magnetic Ethylene-PMO NPs was calculated to be 743 m\({}^{2}\)/g with a pore radius of 2.47 nm. It was calculated by the Barrett-Joyner-Halenda (BJH) method, whereas the surface area of Phenylene-PMO NPs was calculated to be 611 m\({}^{2}\)/g with a pore radius of 1.54 nm, according to BJH calculations. It is worth mentioning that incorporating the magnetic nanoparticles into the cores did not dramatically affect the total surface area value of the synthesized systems.