Europhys. Lett.
Volume 70, Number 5, June 2005
Page(s) 684 - 689
Section Interdisciplinary physics and related areas of science and technology
Published online 29 April 2005
Europhys. Lett., 70 (5), pp. 684-689 (2005)
DOI: 10.1209/epl/i2004-10517-6

Probing glass transition of clay colloids by NMR relaxometry: Interplay between fluid Brownian dynamics and particle jamming

P. E. Levitz and J.-P. Korb

Laboratoire de Physique de la Matière Condensée, UMR 7643 du CNRS Ecole Polytechnique - 91128 Palaiseau, France

received 6 September 2004; accepted in final form 12 April 2005
published online 29 April 2005

Using field cycling NMR relaxometry, we show how the slow water dynamics in the proximity of a colloidal surface provides an original way to follow the glass transition and the strong rotational slowing-down of a colloidal system made of plate-like laponite particles, a synthetic clay. The interplay between fluid Brownian loops near colloidal interfaces (which follows a Lévy statistics) and particle dynamics is discussed. We propose an analytical model of the NMR relaxometry involving elementary time steps of the fluid dynamics near a colloidal interface (e.g., bulk loops, adsorption trains, escaping tails) coupled to the rotational dynamics of the particle. This close-form model is supported by our experimental data.

82.70.Dd - Colloids.
76.60.Es - Relaxation effects.
64.70.Pf - Glass transitions.

© EDP Sciences 2005