# Interfacial Rheology of an Ultrathin Nanocrystalline Film Formed at the Liquid/Liquid Interface

Krishnaswamy, Rema and Majumdar, Sayantan and Ganapathy, Rajesh and Agarwal, Ved Varun and Sood, AK and Rao, CNR (2007) Interfacial Rheology of an Ultrathin Nanocrystalline Film Formed at the Liquid/Liquid Interface. In: Langmuir, 23 (6). pp. 3084-3087.

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## Abstract

We report the interfacial properties of monolayers of Ag nanoparticles 10-50 nm in diameter formed at the toluene-water interface under steady as well as oscillatory shear. Strain amplitude sweep measurements carried out on the film reveal a shear thickening peak in the loss moduli $(G^{\prime}^{\prime})$ at large amplitudes followed by a power law decay of the storage $(G^{\prime})$ and loss moduli with exponents in the ratio 2:1. In the frequency sweep measurements at low frequencies, the storage modulus remains nearly independent of the angular frequency, whereas $G^{\prime}^{\prime}$ reveals a power law dependence with a negative slope, a behavior reminiscent of soft glassy systems. Under steady shear, a finite yield stress is observed in the limit of shear rate $\dot{\gamma}$ going to zero. However, for $\dot{\gamma} > 1 s^{-1}$, the shear stress increases gradually. In addition, a significant deviation from the Cox-Merz rule confirms that the monolayer of Ag nanoparticles at the toluene-water interface forms a soft two-dimensional colloidal glass.

Item Type: Journal Article Copyright of this article belongs to American Chemical Society. Division of Physical & Mathematical Sciences > Physics 29 May 2008 19 Sep 2010 04:45 http://eprints.iisc.ernet.in/id/eprint/14083