Scattering from dilute ferrofluid suspensions in soft polymer gels

TL;DR

This study uses neutron and x-ray scattering to analyze the structure and magnetic field response of dilute ferrofluid particles embedded in soft polymer gels, revealing fractal aggregation and orientation behavior influenced by gel elasticity.

Contribution

It provides new insights into the fractal nature and magnetic orientation of ferrofluid particles within soft polymer gels, highlighting the role of gel elasticity in particle behavior.

Findings

Particles form fractal aggregates with size-dependent fractal dimensions

Aggregates orient under magnetic fields but are restricted by gel elasticity

Different samples show varying fractal dimensions, indicating sample-dependent structure

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.