# Design and Synthesis of Fe3O4-Loaded Polymer Microspheres with Controlled Morphology: Section II Fabrication of Walnut-like Superparamagnetic Polymer Microspheres

## TL;DR

Researchers created walnut-shaped polymer microspheres containing magnetic nanoparticles using a new synthesis method, which could be useful in biomedical applications.

## Contribution

A novel γ-ray-initiated mini-emulsion polymerization method to fabricate walnut-like superparamagnetic polymer microspheres with controlled morphology.

## Key findings

- Fe3O4 nanoparticles were successfully encapsulated in polymer microspheres with a walnut-like structure.
- The microspheres exhibited superparamagnetic behavior and strong magnetic responsiveness.
- Surface modification of Fe3O4 nanoparticles improved their dispersion in the monomer phase.

## Abstract

A simple and innovative synthesis strategy was established to produce polymer microspheres with a distinctive walnut-like morphology, incorporating Fe3O4 nanoparticles within their structure. This was achieved through γ-ray-initiated mini-emulsion polymerization. To ensure high encapsulation efficiency, the surface of the Fe3O4 nanoparticles was chemically altered to shift their wettability from hydrophilic to hydrophobic, enabling uniform dispersion within the monomer phase before polymerization. The formation of the walnut-like architecture was found to be significantly influenced by both the polymerization dynamics and phase separation, as well as the shrinkage of the crosslinked polymer network formed between the monomer and the resulting polymer. Divinylbenzene (DVB) was chosen as the monomer due to its ability to generate a mechanically stable polymer framework. The γ-ray irradiation effectively initiated polymerization while preserving structural coherence. A detailed analysis using FTIR, SEM, and TEM confirmed the successful fabrication of the Fe3O4-loaded polymer microspheres with their characteristic textured surface. Moreover, magnetic characterization via vibrating sample magnetometry (VSM) indicated pronounced superparamagnetic behavior and strong magnetic responsiveness, highlighting the potential of these microspheres for advanced biomedical applications.