# Reactive Polymer Composite Microparticles Based on Glycidyl Metacrylate and Magnetic Nanoparticles
## 4 Conclusions  
The addition of Fe\({}_{3}\)O\({}_{4}\)@OA to the composition of monomers consisting of glycidylI methacrylate (GMA), styrene (S), divinylbenzene (DVB), benzoyl peroxide (an initiator), and toluene (a diluent) resulted in obtaining polymer microparticles that had the unique multi-hollow or raspberry-like morphology and composite character in suspension polymerization. Hydrophobized MNPs added to the monomer composition turned out to be responsible for the stabilization of water droplets in the organic phase and the shaping of the multi-hollow morphology of the provided composite particles during the polymerization. The number of microbubbles formed by stabilized water droplets within the produced polymer microparticles particles increased with increasing amounts of Fe\({}_{3}\)O\({}_{4}\)@OA nanoparticles added, resulting in their surfaces being covered with numerous microcraters that shaped their final raspberry-like morphology. The magnetite nanoparticles used for the polymerization underwent partial embedding within the formed polymer network, providing the composite nature for the polymer microparticles. However, the amount of magnetic nanoparticles encapsulated within the polymer composite microparticles did not exceed 0.1 wt.%; thus, the resulting particles showed only very slight magnetic properties that were insufficient for magnetic separation. The use of divinylbenzene (a crosslinking monomer) in an amount of 3 mol% and styrene in an amount of 77 mol%, as well as the dilution of the monomer mixture with toluene, resulted in the formation of gel-type microparticles with good swelling capacity in THF, toluene, methylene chloride, and the mixture of 1:3 _v.v._ methanol/methylene chloride. Introducing epoxy groups into the polymer network with glycidyl methacrylate molecules allowed the further modification of the composite particles in the reaction with PAMAM-type polymidoamine followed by the immobilization of palladium(II) ions within the microparticles. The materials obtained were thus successfully used as sources of Pd(0) particles that are active in coupling reactions between phenylboronic acid and various aryl bromides. It was concluded that the activity of the catalysts based on the polymer composite microparticles was clearly higher than that of the catalyst based on the polymeric support with the pure gel-type nature. The presence of inorganic nanoparticles embedded within a gel-type polymer matrix appeared to improve the dispersion of Pd(0) species on the surface and inside of the polymer composite supports, making them more active in the Suzuki reaction.  
Conceptualization, W.B. and A.B.; methodology, W.B. and A.B.; formal analysis and investigation, S.F., K.B. and A.B.; data curation, W.B. and A.B.; writing--original draft preparation, W.B. and A.B.; writing--review and editing, W.B. and A.B.; visualization, A.B.; supervision, W.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
**Data Availability Statement:** All data are given in the paper.  
**Conflicts of Interest:** The authors declare no conflict of interest.