The impact of magnetic field on the conformations of supracolloidal polymer-like structures with super-paramagnetic monomers

• Published in: Journal of molecular liquids Vol. 305; p. 112761
• Main Authors: Mostarac, D., Novak, E.V., Sánchez, P.A., Kantorovich, S.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2020
• Subjects: Central attraction; Crosslinked polymer-like structures; Langevin dynamics simulations; Super-paramagnetic particles; Central attraction; Crosslinked polymer-like structures; Super-paramagnetic particles; Langevin dynamics simulations
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2020.112761

We investigate the properties of magnetic supracolliodal polymers – magnetic filaments (MFs) – with super-paramagnetic monomers, with and without Van der Waals (VdW) attraction between them. We employ molecular dynamics (MD) simulations to elucidate the impact of crosslinking mechanism on the structural and magnetic response of MFs to an applied external homogeneous magnetic field. We consider two models: plain crosslinking, which results in a flexible backbone; and constrained crosslinking, which provides significant stiffens against bending. We find that for plain crosslinking, even a slight increase of the central attraction leads to collapsed MF conformations. Structures that initially exhibit spherical symmetry evolve into cylindrically symmetric ones, with growing magnetic field strength. Plain crosslinking also allows for conformational bistability. MFs with constrained crosslinking tend to, instead, unravel in field. In both crosslinking scenarios, central attraction is able to hinder low-field magnetic response of MFs, albeit the bistability of plainly crosslinked MFs manifests itself also in the high-field region. •Model of filaments with super-paramagnetic beads was developed.•Van Der Waals forces have a strong impact on filament conformations in applied field.•Plainly crosslinked filaments change from spherically to cylindrically symmetric conformations in field.•Super-paramagnetic nature of monomers leads to instability of conformations.