Fe₃O₄ nanoparticles coated with a guanidinium-functionalized polyelectrolyte extend the pH range for phosphate binding

In this work commercially available Fe3O4 NPs were coated with polyallylamine hydrochloride (PAH) and PAH functionalized with guanidinium groups (PAH–Gu) for investigating the phosphate adsorption properties under alkaline conditions. The coating can be prepared easily and rapidly and results in Fe3O4 NPs with improved properties related to...

Mimicking an Atomically Thin "Vacuum Spacer" to Measure the Hamaker Constant between Graphene Oxide and Silica

The Hamaker constant between graphene oxide and silica, which quantifies the strength of van der Waals forces is determined, by mimicking a “vacuum spacer” in an atomic force microscopyforce study. It is demonstrated that, a 2D spacer is expected to yield an accurately defined separation, owing to the high atom density and strength in planar...