Synthesis of Fe₃O₄/PAM superparamagnetic nano-hydrogels in water-in-oil emulsion

Abstract

In this study, the nano-sized water droplets (NWDs) in water-in-oil (W/O) emulsion were employed as mini-reactors, in which Fe₃O₄/PAM magnetic nano-hydrogels (MNHs) were obtained based on the coprecipitation and inverse emulsion polymerization. In addition, compound nonionic surfactant was used as the stabilizer of W/O emulsion. The test results showed that Fe₃O₄/PAM MNHs were quasi-sphere particles with a diameter of about 50–380 nm and had superparamagnetism. The percentage of PAM coating Fe₃O₄ was about 81%. The saturation magnetization of the Fe₃O₄/PAM MNHs was 21.6 emu/g (Fe₃O₄/AM (wt/wt) = 16.63%). The W/O emulsion containing Fe₃O₄/PAM MNHs (E-2) changed from fluid to solidlike in an external magnetic field. As current intensified or shear rate increased, the shear stress of E-2 increased.

GRAPHICAL ABSTRACT

Keywords:

• MNHs
• superparamagnetism
• NWDs
• compound nonionic surfactant

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Daqing Normal University Scientific Research Fund under Grant number 14ZR13.