Scattering from dilute ferrofluid suspensions in soft polymer gels

Abstract

Small angle neutron and x-ray scattering methods are used to investigate the structure of dilute suspensions of two different ferrofluid systems dispersed in soft polyacrylamide hydrogels. It is found that the particles in the fluid are fractal aggregates composed of smaller particles of radius ca. 5 nm. The fractal dimension is strongly dependent on sample, taking the value 1.7 in the first sample and 2.9 in the second sample. In the presence of a magnetic field the aggregates orient, but are restricted in both their translational and rotational freedom. The effect of the gel elasticity is treated as a hindrance to the orientation process.

Local structure of polymeric ferrogels

“…They are based on the intimate mixing of polymeric gels and magnetic particles [1,2]. Frequently, in order to mechanically reinforce the polymeric structure, the particles are aggregated [3][4][5]. The swelling of the system is then seriously hindered.…”

Thermoreversible Ferrogels

“…For biomedical and pharmaceutical applications, aqueous FFs have been developed. [8,9] Starting from FFs, another kind of magnetically responsive soft materials known as ferrogels (FGs) [10][11][12][13][14][15][16][17][18][19][20] have been described. Due to their unique magnetoelastic properties, intelligent or smart FGs are the object of numerous theoretical investigations.…”

Local deformations of ferrogels induced by uniform magnetic fields

“…B and achieving a saturation in after $ 500 mT for all samples. In our previous work [1] we reported an opposite tendency of the scattered intensity variation from a scattering vector $ 0:005 ( A…”

“…Some effort has been made in a sense to describe the internal structure of magnetic particles dispersed in a viscous medium (ferrofluid) and in a elastic medium (ferrogel). It has been shown that particles can form small aggregates or rod-like shapes [5] depending on the magnetic and thermal energies and as in ferrogels they can form aggregates or fractal structures [1]. In presence of uniform magnetic fields it is expected an orientation of the magnetic particles which causes linear aggregation in ferrofluids [6] and deformation in ferrogels [1].…”