# Reactive Polymer Composite Microparticles Based on Glycidyl Metacrylate and Magnetic Nanoparticles
## 3 Results and Discussion
### Preparation of Epoxy Functionalized Composite Microparticles
However, a further increase in the stirring rate to 600 rpm caused an increase in the dispersity of particle size (Table 1, Entry 8). Figure 1: Size distribution of Fe\({}_{3}\)O\({}_{4}\)@OA particles in toluene magnetic fluid. As mentioned above, the polymer particles synthesized in the presence of Fe\({}_{3}\)O\({}_{4}\)@OA were characterized by a brownish color. This finding indicated that part of the magnetite particles underwent encapsulation inside the final polymer beads. However, the observed color of the polymer composite particles seemed to suggest that some of the magnetite particles could oxidize to maghemite ones during the polymerization and post-polymerization washing operations. The ICP OES analysis preceded by a previous mineralization of particle samples revealed that about 14% to 36% of the magnetite particles added to the monomer mixture were embedded in the final polymer beads. The percentage of Fe\({}_{3}\)O\({}_{4}\)@OA embedded in the polymer microparticles increased with increasing amounts of magnetite nanoparticles being added to the monomer composition. However, at the same time, the percentage of Fe\({}_{3}\)O\({}_{4}\)@OA particles encapsulated decreased in the same order. Microphotographs taken using an optical stereomicroscope equipped with a digital camera showed that polymer particles that did not contain the Fe\({}_{3}\)O\({}_{4}\)@OA additive differed in their transparency compared to those obtained in the presence of magnetite particles (Figure 4). They are also different from the polymer particles that were obtained based on the GMA-S-DVB composition diluted with the cyclohexanol/1-octanol mixture [55]. The  
Figure 3: Size distributions of polymer particles prepared in the presence of Fe\({}_{3}\)O\({}_{4}\)@OA depending on the stirring rate. Figure 2: Size distributions of polymer particles prepared using 20 mol% GMA, 77 mol% S, and 3 mol% DVB and Fe\({}_{3}\)O\({}_{4}\)@OA particles as an additive. rather milky appearance of the polymer microparticles obtained using toluene indicated that this solvent acts not only as a diluent for the monomer composition, but also as a porogen for the polymer network of particles formed under the applied polymerization conditions [59]. This phenomenon probably resulted from the incompatibility of hydrophobic toluene molecules and polar glycidyl methacrylate molecules that were present in the monomer composition in the amount of 20 mol%. Furthermore, the microphotographs revealed that the polymer particles obtained in the presence of 0.05 and 0.1 wt.% Fe3O4@OA contained microbubbles inside and appeared to resemble the multihollow morphology particles described by [PERSON] et al. [39]. The number of microbubbles ('gigapores') in individual particles increased as the amount of Fe3O4@OA in the monomer composition increased. Furthermore, the particles provided using 0.25 wt.% Fe3O4@OA and more were characterized by a raspberry-like morphology like the particles described in refs. [60,61]. More details on the morphology of the obtained particles were revealed after their examination using a SEM technique (Figure 5). The SEM images revealed the complex morphology of composite microparticles, which was initially concluded based on the optical microphotographs. Furthermore, the SEM images revealed that the surfaces of the composite microparticles are covered with numerous microcraters. The number of microcraters increased with an increasing concentration of Fe3O4@OA particles in the monomer composition. Furthermore, the SEM analysis proved that the particles had an inhomogeneous morphology without the use of Fe3O4@OA particles (Figure 5). The presence of numerous bubbles on the surface of the polymer particles appears to indicate this. Figure 4: Microphotographs of GMA-based polymer microparticles prepared (**A**) without Fe3O4@OA (**1a**) and with (**B**) 0.05 (**1b**), (**C**) 0.10 (**1c**), (**D**) 0.25 (**1d**), (**E**) 0.5 (**1e**), and (**F**) 0.75 wt.% Fe3O4@OA (**1f**) additive.