Synthesis of magnetic Fe3O4/polyamine hybrid microsphere using O/W/O Pickering emulsion droplet as the polymerization micro-reactor

Abstract

In order to obtain a magnetic polyamine microsphere, a magnetic oil–water-in-oil multiple emulsion droplet was used as the micro-reactor and template for polymerization. The influences of magnetite (NanoFe₃O₄) and the polymer precursor polyethyleneimine (PEI) on the properties of an emulsion were investigated. After using hydrophobic CaCO₃ nanoparticles (SM-CaCO₃) in the emulsification, the liquid paraffin-in-water emulsion stabilized by NanoFe₃O₄ and PEI was changed to an O/W/O Pickering emulsion. The investigation found that suspensions of 2 wt% SM-CaCO₃ in liquid paraffin should be emulsified with 1 wt% NanoFe₃O₄ in 20 wt% PEI solution at a ϕ_w of 0.5 in order to incorporate as much PEI as possible, in emulsion droplets, while avoiding the phase inversion of emulsion. After the crosslinking of PEI in the emulsion droplets by glutaraldehyde, a magnetic Fe₃O₄/polyamine microsphere with both hydrophilic and hydrophobic characteristics was obtained. The microsphere demonstrated an isoelectric point of 9.6. The magnetic capacity of NanoFe₃O₄ decreased as a result of being trapped in the polyamine matrix of the microsphere.