β-cyclodextrin and carbonyl iron-based supramolecular gels: microstructure and magnetorheology

This study presents the development of supramolecular gels composed of β-cyclodextrin (β-CD) and carbonyl iron (CI) particles, offering an effective combination of enhanced stability and magnetorheological (MR) responsiveness. Unlike conventional CI-based systems prone to rapid sedimentation, the β-CD matrix in this composite prevents particle aggregation, demonstrating sedimentation stability for up to 12 h without visible sedimentation. Microstructural analysis using small-angle x-ray scattering and scanning electron microscopy revealed that the inclusion of CI particles significantly modifies the gel structure, enabling a highly tunable MR response. Rheological tests demonstrated a critical magnetic field (H _C) as low as ∼150 Oe, indicating an early magnetic response, which leads to a significant increase in viscosity and yield stress under magnetic influence. A phase diagram is proposed to explain the underlying MR mechanisms. This novel system offers a new approach to designing magneto-responsive materials with controlled mechanical properties, making them suitable for various smart material applications.