Local structure of polymeric ferrogels

We synthesize hybrid gels incorporating γ‐Fe2O3γ‐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.

Research Highlights
► Hybrid ferrogels are formed with citrate coated γ-Fe2O3 NPs added to PAM networks.
► We probe both local organisation and rotational degrees of NPs in the ferrogels.
► Structural homogeneity is correlated with synthesis parameters and elasticity.
► At low [cit] free, NP adsorption on PAM network reinforces the polymer structure.
► At higher [cit] free, NPs desorb from polymer structure weakening the system.