Colloidal Interactions in Low-polarity Dispersions of Permanently Magnetic Nanoplatelets
5 affiliations
- 1Department for Materials Synthesis Jožef Stefan Institute Jamova cesta 39, 1000 Ljubljana
- 2Jožef Stefan International Postgraduate School Jamova cesta 39,
- 3Advanced Materials Department Jožef Stefan Institute Jamova cesta 39, 1000 Ljubljana
- 4Chair of Organic Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana, Slovenia, 1000
- 5Department of Complex Matter Jožef Stefan Institute Jamova cesta 39, 1000 Ljubljana
Abstract
Ferrofluids based on permanently magnetic nanoplatelets are attractive functional materials. However, their preparation in low-polarity media is particularly challenging because magnetic dipole–dipole interactions strongly promote agglomeration while conventional electrostatic stabilisation is weakened. Here, low-polarity dispersions of barium hexaferrite nanoplatelets were prepared by functionalising the particles with ricinoleic acid (RA) and dispersing them in low-polarity solvents of different chemical character. The resulting dispersions exhibited markedly different colloidal stabilities, ranging from stable ferrofluids in chlorinated solvents to unstable dispersions in toluene and decalin. Infrared spectroscopy and thermogravimetric analysis confirmed successful functionalisation with RA and indicated the presence of both chemisorbed and loosely bound RA species. Electrokinetic measurements revealed a clear correlation between colloidal stability and the development of a surface charge. Based on these results, we propose that stable dispersions are stabilised by an electro-steric-solvation mechanism that enables spatial stabilisation of charge in low-polarity media. A fraction of the RA is chemisorbed on the nanoplatelet surface, while loosely associated RA species, together with locally ordered solvent molecules, are proposed to stabilise the negative countercharge, thereby maintaining its separation from the positively charged nanoplatelet surface. This charge separation generates a repulsive barrier that counterbalances magnetic dipole–dipole attraction and prevents agglomeration. These findings highlight charge stabilisation in low-polarity media as a key requirement for preparing stable ferrofluids based on permanently magnetic anisotropic nanoparticles.
Related
- Competing Colloidal Interactions Govern Polymer Encapsulation of Hydrophobic Iron Oxide Nanoparticles.
- Production and thermal performance evaluation of graphene nanoplatelets/Al₂O₃-reinforced Al6061–Cu hybrid thermal interface material
- Epoxy and Vinyl Silane Functionalization of Graphene Nanoplatelets
- Capturing Transient Growth Windows for Narrow-Emitting Perovskite Nanoplatelets
- A Review of Antimicrobial Mechanisms of Graphene Oxide, Reduced Graphene Oxide, and Graphene Nanoplatelets: Implications for Polymer-Based Dental Materials
BibTeX
@misc{trucl2026colloidal,
title = {{Colloidal Interactions in Low-polarity Dispersions of Permanently Magnetic Nanoplatelets}},
author = {Jošt Tručl and Marjeta Maček Kržmanc and Jure Gregorc and Jernej Iskra and Alenka Mertelj and Darja Lisjak},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008384/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008384/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Colloidal Interactions in Low-polarity Dispersions of Permanently Magnetic Nanoplatelets
AU - Jošt Tručl
AU - Marjeta Maček Kržmanc
AU - Jure Gregorc
AU - Jernej Iskra
AU - Alenka Mertelj
AU - Darja Lisjak
PY - 2026
DA - 2026/09/07
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008384/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008384/v1
AB - Ferrofluids based on permanently magnetic nanoplatelets are attractive functional materials. However, their preparation in low-polarity media is particularly challenging because magnetic dipole–dipole interactions strongly promote agglomeration while conventional electrostatic stabilisation is weakened. Here, low-polarity dispersions of barium hexaferrite nanoplatelets were prepared by functionalising the particles with ricinoleic acid (RA) and dispersing them in low-polarity solvents of different chemical character. The resulting dispersions exhibited markedly different colloidal stabilities, ranging from stable ferrofluids in chlorinated solvents to unstable dispersions in toluene and decalin. Infrared spectroscopy and thermogravimetric analysis confirmed successful functionalisation with RA and indicated the presence of both chemisorbed and loosely bound RA species. Electrokinetic measurements revealed a clear correlation between colloidal stability and the development of a surface charge. Based on these results, we propose that stable dispersions are stabilised by an electro-steric-solvation mechanism that enables spatial stabilisation of charge in low-polarity media. A fraction of the RA is chemisorbed on the nanoplatelet surface, while loosely associated RA species, together with locally ordered solvent molecules, are proposed to stabilise the negative countercharge, thereby maintaining its separation from the positively charged nanoplatelet surface. This charge separation generates a repulsive barrier that counterbalances magnetic dipole–dipole attraction and prevents agglomeration. These findings highlight charge stabilisation in low-polarity media as a key requirement for preparing stable ferrofluids based on permanently magnetic anisotropic nanoparticles.
ER -