Buckling of paramagnetic chains in soft gels

TL;DR

This study investigates how paramagnetic chains embedded in soft gels deform under magnetic fields, revealing complex buckling behaviors influenced by chain length, field strength, and gel stiffness, supported by experiments and simulations.

Contribution

It introduces a combined experimental and simulation approach to understand magneto-elastic buckling of paramagnetic chains in soft gels, highlighting the strong coupling with the gel network.

Findings

Paramagnetic chains exhibit rich buckling morphologies under magnetic fields.

The morphology depends on chain length, magnetic field strength, and gel modulus.

Simulations replicate experimental buckling behaviors with increased matrix stiffness.

Abstract

We study the magneto-elastic coupling behavior of paramagnetic chains in soft polymer gels exposed to external magnetic fields. To this end, a laser scanning confocal microscope is used to observe the morphology of the paramagnetic chains together with the deformation field of the surrounding gel network. The paramagnetic chains in soft polymer gels show rich morphological shape changes under oblique magnetic fields, in particular a pronounced buckling deformation. The details of the resulting morphological shapes depend on the length of the chain, the strength of the external magnetic field, and the modulus of the gel. Based on the observation that the magnetic chains are strongly coupled to the surrounding polymer network, a simplified model is developed to describe their buckling behavior. A coarse-grained molecular dynamics simulation model featuring an increased matrix stiffness on the surfaces of the particles leads to morphologies in agreement with the experimentally observed buckling effects.