Simulation of magneto-mechanical response of ferrogel samples with various polymer structure

Following the coarse-grained molecular dynamics approach, we propose a model of a small ferrogel sample (containing up to 1000 magnetic nanoparticles), in which the polymer matrix is presented in the form of a quasi-regular mesh of spring-beads chains and the filler particles are located at the mesh nodes. The state of the sample in the absence of an external field and in the process of quasi-static magnetization is considered for two types of mesh topology (simple cubic and diamond-like), different values of the filler concentration, the strength of dipole interaction, and the energy of magnetic anisotropy. Simulation shows that the use of a softer matrix with a diamond-like structure increases the magneto-mechanical response of the ferrogel. The presence of magnetic anisotropy leads to effective hardening of the ferrogel and, thus, prevents particle clustering and sample magnetization. It was also found that the anisotropy energy determines the type of field-induced changes in the sample volume - this aspect of material behavior is important for the use of ferrogels in controlled delivery and/or release of drugs.