# Reactive Polymer Composite Microparticles Based on Glycidyl Metacrylate and Magnetic Nanoparticles
## 3 Results and Discussion
### Preparation of Epoxy Functionalized Composite Microparticles
A SEM EDS analysis was performed for randomly selected craters on the surfaces of the composite beads (Figure 6). The presence of Fe atoms was detected at points 1 and 4, respectively, located inside and in the immediate vicinity of the examined crater. These findings demonstrate that Fe\({}_{3}\)O\({}_{4}\)@OA particles play an active role in the formation of the raspberry-like or multi-hollow-like morphology of the composite microparticles produced. Hydrophobic nanoparticles and microparticles are capable of stabilizing water/oil emulsions during polymerization [62, 63, 64, 65]. It is probable that, thanks to this feature, the hydrophobic nanoparticles of Fe\({}_{3}\)O\({}_{4}\)@OA can easily disperse in the monomer phase and participate in the formation of 'giga' pores in the polymer composite microbeads provided as a consequence of polymerization. Figure 5: SEM images of GMA-based polymer microparticles prepared without Fe\({}_{3}\)O\({}_{4}\)@OA (**1a**) and with 0.05 (**1b**), 0.25 (**1d**), 0.5 (**1e**), and 0.75 wt.% Fe\({}_{3}\)O\({}_{4}\)@OA (**1f**) additive. Figure 6: Distribution of iron atoms within composite microparticles obtained using 0.25 wt.%-Fe\({}_{3}\)O\({}_{4}\)@OA (**1d**). An increase in the number of Fe\({}_{3}\)O\({}_{4}\)@OA nanoparticles embedded in the resulting polymer composite particles should affect the magnetic properties of the latter. A very slight magnetic effect was only observed for the final microparticles that were obtained using 0.25 wt.% and more Fe\({}_{3}\)O\({}_{4}\)@OA in relation to the monomers (Figure 7). The composite microparticles were also analyzed to assess the loading of epoxy groups introduced with GMA. The modified Jay method was applied [55]. The results obtained are presented in Table 2. When comparing these results with those previously obtained for GMA resins using the cyclohexanol/1-octanol mixture [55], it was concluded that, despite a certain 'incompatibility' in polarity between GMA and toluene molecules, the polymer composite particles obtained using toluene were characterized by epoxy group loadings comparable to those obtained previously [55]. The chemical structure of the composite particles was also studied by FTIR spectroscopy. The FTIR spectra of the provided particles were dominated by the absorption bands corresponding to the group characteristics of the monomers used for the polymerization (Figure 8). The adsorption bands at 1724 cm\({}^{-1}\) (vC=O), between 1330 and 1050 (skeletal vibration of C-O-C) and at 908 and 825 cm\({}^{-1}\) (epoxy ring stretching), can be attributed to GMA units. The bands observed in the ranges of 3080 to 2850 and 1600 to 1450 cm\({}^{-1}\) confirm the presence of aliphatic and aromatic hydrocarbyl groups in the polymer structure. Due to the very low amount of Fe\({}_{3}\)O\({}_{4}\) particles (below 0.1 wt.%) embedded in the final composite microparticles, the absorption band corresponding to the Fe-O-Fe skeletal vibrations in Fe\({}_{3}\)O\({}_{4}\) (at approximately 570 cm\({}^{-1}\)) was slightly visible in the spectra of composite particles as it was obscured by the much more intensive band of six-membered aromatic rings (Figure 8). \begin{table}
\begin{tabular}{c c c c c} \hline
**Polymerization** & **Epoxy Group** & **Modification** & **Nitrogen Content,** & **Epoxy Group** \\
**Product** & **Loading, mmol/** & **Product** & **wt.\%** & **mmol/g** & **Conversion, \%** \\ \hline
**1a** & 1.33 & - & - & - & - \\
**1d** & 1.25 & **2d** & 4.99 & 3.56 & 36 \\
**1e** & 1.29 & **2e** & 5.74 & 4.10 & 41 \\ \hline \end{tabular}
\end{table} 
Table 2: Characteristics of composite microparticles modified with PAMAM. Figure 7: The performance of **1d** microparticles under the influence of a neodymium magnet. The swelling capacity of the obtained composite microparticles was also examined. The knowledge of this feature can be interesting from the point of view of further potential chemical modifications of the microparticles.