Self-assembly of ferroferric oxide liquid-crystalline nanocomposites bearing cholesteryl mesogens and ionic groups

ABSTRACT

Magnetorheological fluids (MRFs) are promising smart materials that can respond to an external field. In order to obtain stable suspension and investigate the settlement law of these synthesised MRFs, polymerised ionic liquid crystalline (PILC) ferroferric oxide nanocomposites (Fe₃O₄@PILCs), the dispersed phase in MRFs, were obtained by self-assembly of magnetic Fe₃O₄ nanoparticles with PILCs. The structural properties, thermotropic liquid crystal characteristics, morphology and microscopic magnetic response characteristics were investigated in this study. Fe₃O₄@PILCs showed nematic liquid crystal behaviour, and the mesogenic phase range was affected by the content of cholesteryl-based LC mesogen containing carboxylic acid groups. Series of MRFs were prepared by the Fe₃O₄@PILCs with 5% particles mass fractions in different volume fractions. The settlement stability as well as the settlement laws was investigated comprehensively and systematically for these MRFs. The Fe₃O₄@PILC-based MRFs exhibited better sedimentation stability than the bare Fe₃O₄-based MRFs, indicating that the Fe₃O₄ particles self-assembled with PILCs could reduce the density of the dispersed phase and showed the good compatibility with silicone oil carrier fluid. The sedimentation velocity curves of the Fe₃O₄@PILC-based with different particle volume fractions were investigated by use of some relevant theoretical models, indicating that they were the most consistent with the Dick’s model.

GRAPHICAL ABSTRACT

KEYWORDS:

• Magnetorheological fluids
• ferroferric oxide nanocomposites
• sedimentation stability
• settling velocity model
• liquid-crystalline behaviour

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Fujian Provincial Key Laboratory of Featured Biochemical and Chemical Materials, Ningde Normal University [Project FJKL_FBCM202101] and Scientific Research Fund project of Ningde Normal University [2020Z02, 2020T01].