# Reactive Polymer Composite Microparticles Based on Glycidyl Metacrylate and Magnetic Nanoparticles
## 3 Results and Discussion
### Attempts of Chemical Modification and Application of Composite Microparticles  
As was mentioned in the Introduction Section, introducing epoxy groups into insoluble materials can be useful from the point of view of their subsequent chemical modifications. Therefore, the selected polymerization products (**1d** and **1e**), provided using 0.25 and 0.50 wt.% Fe\({}_{3}\)O\({}_{4}\)@OA, respectively, were modified according to Scheme 2 in the reaction with the zero-order PAMAM dendrimer. The modification was carried out similarly to that performed in the case of gel-type GMA-S-DVB terpolymers [66]. To prove the efficiency of the transformation of epoxy groups under the influence of primary amine groups in PAMAM, the FTIR spectra of the modified products were recorded and compared with the spectrum of epoxy-functionalized microparticles (Figure 11). A decrease in absorption in the range characteristic for the stretching vibration of the epoxide rings (908 and 825 cm\({}^{-1}\)) and an increase in absorption in the range extending from 3600 to 3100 cm\({}^{-1}\) corresponding to the stretching vibrations of the hydroxy and amine groups indicated the conversion of epoxy groups under the influence of PAMAN amine groups. Furthermore, the introduction of polyamineamide PAMAM units into the structure of the starting materials was demonstrated by the appearance of the new absorption bands at 1654 and 1546 cm\({}^{-1}\), which correspond to the vibrations of the amide units. Figure 10: Thermogravimetric curves obtained for **1e**. To assess the amino group loadings, the nitrogen contents in the modified particles were determined using the Kjeldahl method. Nitrogen percentages of 4.99-5.74 wt.% were found (Table 2). The values obtained pointed to approximately a 40% conversion of epoxy groups. The composite microparticles with immobilized PAMAM units (**2d** and **2e**) were then impregnated with the solutions of palladium(II) acetate in THF. Impregnation was performed at room temperature and lasted 24 h. An equivalent of Pd(II) ions in relation to the amine groups was applied to immobilize palladium(II) ions within the composite microparticles (Scheme 3). Figure 11: Comparison of FTIR spectra of **1d** and **2d**. Only slight changes in color were observed for the resulting microparticles after impregnation (Figure 12). However, the occurrence of Pd(II) ion immobilization was proven by comparing the FTIR spectra of the microparticles recorded before and after impregnation (Figure 13). The comparison revealed an appearance of the new absorption bands in the spectra of the products at ~1560 and 1320 cm\({}^{-1}\). These findings could be attributed to vibrations within the C=O and C-O bonds, respectively, in the acetate ions [67]. The observation indicated that the Pd(II) ions underwent immobilization within the PAMAM-functionalized microparticles in the presence of acetate ions. However, the observed spectral changes did not point to which donor atoms are responsible for the immobilization of palladium(II) acetate. It is well known that Pd(II) ions generally form tetracoordinate complexes and can interact with various donor atoms. In the case of the polymer composite particles obtained based on glycidyl methacrylate modified with PAMAM and used as a support for Pd(CH\({}_{3}\)COO)\({}_{2}\), theoretically, two groups of donor atoms (with oxygen and nitrogen atoms) can participate in coordination. However, the better donor properties in relation to Pd(II) ions seem to present nitrogen-type donors, particularly those located on amine groups. To underline the probable interactions, palladium species were located near these atoms/groups in the simplified scheme that presented a palladium-supported catalyst based on the obtained PAMAM-functionalized polymer composite particles. Figure 12: Comparison of microphotographs of **2d (A)**, **2e (B)**, **3d (C)**, and **3e (D)**. ICP analyses of **3d** and **3e** were also performed.