Iron nanoparticles dispersible in both ethanol and water for direct silica coating

An amphiphilic polymer dispersant–polyvinyl pyrrolidone (PVP)–was used as a dispersant to make iron suspensions. The stability of the suspensions was characterized by conducting UV/vis transmittance and rheological analyses and sedimentation tests. We found that PVP was not only effective in dispersing iron nanoparticles in ethanol, but also in stabilizing them in deionized water by coordination interaction through its carbonyl group. The iron nanoparticles functionalized with PVP have another advantage: they could be directly used to coat a silica layer without further modification by other surfactants.