Magnetic nanoparticle-based hydrogels as reliable platforms to investigate magnetic interactions

In this work we design and synthesize magnetic nanoparticle-based hydrogels in which the inter-particle dipolar interactions can be tailored within the networks. These emerging materials combine the porosity and high surface area characteristic of gels with the nanoscopic magnetic properties of the building blocks, all in one macroscopic material. The synthesis of self-supported magnetic nanocrystal-based hydrogels is done through an amphiphilic overcoating and gelation procedure. The control over the dipolar interactions within the nanoparticles and aggregates forming the hydrogel network is achieved by changing the length of the hydrophobic side chain of the amphiphilic polymer used to coat and water transfer the nanoparticles. A scale-up approach of the overcoating procedure is presented. As well, we demonstrate that these systems are very useful to study, understand and easily tailor the magnetic interactions between particles or aggregates, in a more controlled and reliable way than in the nanoparticle colloids.