8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P9.14Tue 611:23-14:00Shear-driven solidification of dilute colloidalsuspensionsEmanuela Del Gado, 1 Alessio Zaccone, 2 Daniele Gentili, 1 Hua Wu, 1 and MassimoMorbidelli 11 ETH Zurich, Schafmattstrasse 6, 8093, Zürich, Switzerland2 University of Cambridge, Cambridge, United KingdomShear-driven solidification of diluted colloidal suspensions has dramatic impact on their applications,ranging from industrial production of paints to artificial or natural microfluidic devices aswell as being a prototype of far from equilibrium transitions. In a set of experiments on dilute,charge-stabilized, colloidal suspensions we combine light scattering, rheology, microscopy andmodeling to rationalize the shear-induced solidification [1]. We show that it is the consequence ofthe interplay between the shear-induced breakage and formation of large non-Brownian clusters.The effective packing fraction of the aggregates formed under shear increases with time. Uponflow cessation their dense packing is progressively frozen into a rigid structure by the formation ofgrainy (i.e. multiple) colloidal bonds which ensure the cohesion of the solid and are responsible forthe fairly high shear moduli observed [1, 2]. The emerging picture of shear-driven solidification indilute colloidal suspensions combines the features of colloidal gelation in Brownian suspensionsand jamming in athermal systems.[1] A. Zaccone, D. Gentili, H. Wu, M. Morbidelli and E. Del Gado, Phys. Rev. Lett. 106,138301 (2011).[2] A. Zaccone, H. Wu and E. Del Gado, Phys. Rev. Lett. 103, 208301 (2009).14