Density variation-induced sign change of the effective hamaker constant in continuum theory.
The density variation-induced dewetting model is reformulated in terms of the Dzyaloshinskii-Lifshitz-Pitaevskii continuum theory for van der Waals interactions. Though the density dependence is more complicated than in the London-Hamaker microscopic theory, numerical calculations for model polystyrene films show that the two theories yield qualitatively similar results. The physics of the dewetting model is thus not changed. Quantitatively, the differences between the two theories are notable. The calculations also show that a linear approximation suffices to take density variations into account, thus simplifying the density variation-induced dewetting models.
Kaya
Håkon
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Microgravity Research Centre, Service Chimie Physique EP - CP 165/62, Université Libre Bruxelles, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium.