Eur. Phys. J. E (2006) 20: 109-117
https://doi.org/10.1140/epje/i2006-10007-3

Regular Article

Surface-functionalized nanoparticles with liquid-like behavior: The role of the constituent components

¹ Department of Materials Science and Engineering, Cornell University, 14853, Ithaca, NY, USA
² School of Chemical and Biomolecular Engineering, Cornell University, 14853, Ithaca, NY, USA
³ Department of Physics, University of Ioannina, Greece
⁴ Biomedical Research Institute (BRI)-FORTH, Ioannina, Greece
⁵ Department of Materials Science, FORTH-IESL, P.O. Box 1527, 71110, Heraklion, Crete, Greece
⁶ Max Planck Institute for Polymer Research, P.O. Box 3148, Mainz, Germany

^* e-mail: fytas@iesl.forth.gr

Received: 11 January 2006
Accepted: 24 April 2006
Published online: 17 May 2006

Abstract

Ionically modified silica nanoparticles with large counter anions (sulfonate, isostearate) at two silica volume fractions (13 and 27%) form a viscous fluid and a glass but not crystalline solids. Dielectric spectroscopy, Brillouin scattering and shear rheometry were employed to investigate these new nanoparticle-based fluids. The glass transition temperature and hence the local dynamics are governed by the large counter anions, whereas the flow properties can be controlled by the spatial correlation between the nanoparticles, e.g. by tuning the volume fraction of hard cores and local interactions between segments in the soft corona. Liquid-like ordering of the cores was revealed by X-ray scattering and found to influence significantly the macroscopic flow properties of these salts.