Nanoparticle in a Nanofluid Film Spreading on a Surface

Original entry by Hyerim Hwang, AP 226, Spring 2012. not finished

Reference

Alex Nikolov, Kirti Kondiparty, and Darsh Wasan, "Nanoparticle Self-Structuring in a Nanofluid Film Spreading on a Solid Surface", Langmuir 2010 26(11), 7665-7670

Keywords

Thin film stability, Nanofluids, Disjoining pressure

Introduction

Figure 1.Photomicrograph depicting nanofluid film formation.

This paper investigates the complex mechanism involved in the solid-nanofluid-oil interactions by directly observing the phenomenon of nanoparticle self-layering due to confinement of nanoparticles in a thin film. This research also shows that the effect of film size on stability of nanolfluid films on a solid substrate.

Figure 2. (a) Film with dimple in the shape of a horseshoe and (b) filme with four particle layers. (c) With time, a film with three layers of particles.

Figure 3. Photomicrograph depicting particle layering of silica suspension on a solid surface.

Figure 4. (A) Photomicrograph depicting the nanofluid film and the adjoining meniscus. (B) Differential interferometry in reflected light. (C) Film-meniscus profile.

Figure 5. Profile of the nanofluid film-meniscus region as probed by differential interferometric method.

Figure 6. Film-meniscus microscopic contact angle versus film thickness and corresponding number of particle layers in a stratifying nanofluid film on a surface.

Figure 7. Calculated oscillatory film structural energy isotherm as a function of film thickness scaled by the effective particle diameter.

Discussion

In this paper, the experimental results of the nanoparticle self-ordering and stepwise thinning of the nanofluid film fromed between an oil drop and a solid surface are reported. This also presents the measured contact angle of film-meniscus and thickness corresponding to the number of particle layers on a solid surface. These were used for getting the film energy due to the nanoparticle layering within the nanofluid film.