Autostratification in drying colloidal dispersions: effect of particle interactions.
When particles differing in size or charge are mixed and cast, vertical segregation is an inevitable phenomenon in the produced films. Apart from the Peclet number, which is the ratio of evaporation to diffusion rates, particle interactions play a crucial role in determining the distribution of particles in the dried films. Trueman et al. (1)  developed a model for vertical segregation of particles during drying. Their numerical solution assumed that the chemical potentials were determined entirely by entropy. We report the effect of particle interactions in various systems: (i) charged particles with different Peclet numbers and (ii) charged particles with the same Peclet numbers. An experimental study has also been carried out for particles with Peclet numbers straddling unity; the experimental results conform with the behavior predicted theoretically.
Department of Chemical Engineering & Biotechnology and BP Institute, University of Cambridge, Madingley Rise, Cambridge CB3 0EZ, United Kingdom.
Anand K
AK
Atmuri
Surita R
SR
Bhatia
Alexander F
AF
Routh