Local structure of polymeric ferrogels

We synthesize hybrid gels incorporating γ‐Fe₂O₃ nanoparticles (NPs), citrate coated, in a polyacrylamide (PAM) network. The local organisation and the rotational degrees of magnetic nanoparticles are probed in the conditions of gel synthesis and also at swelling equilibrium, to correlate the homogeneous/inhomogeneous structure of the ferrogels to the synthesis parameters and to their macroscopic elasticity. NP adsorption on the PAM network at low citrate concentration is responsible for the reinforcing of the polymer structure. At higher citrate concentration, due to a competition between citrate and NPs, the nanoparticles desorb from the polymer structure weakening the system.