Magneto-mechanical coupling in CoFe2O4-linked PAAm ferrohydrogels

Abstract

Magnetically blocked CoFe2O4 nanoparticles are used as nanoscopic mechanical probes in PAAm solutions and gels with different architectures. From quasi-static magnetometry, we extract information on the mechanical feedback from the local restoring forces on the rotational remagnetization of the probes. While the hysteretic magnetic behavior of conventionally crosslinked PAAm ferrohydrogels can be explained by the predominantly viscous processes involved with particle rotation, a reversible, Langevin-like magnetization curve is found in particle-linked ferrohydrogels. From the local restoring force, we conclude on the elastic moduli of the underlying process, in accordance with expectations from statistical thermodynamics.