Dewetting of ultra-thin polymer films near the glass transition exhibits unexpected front morphologies [G. Reiter, Phys. Rev. Lett., 87, 186101 (2001)]. We present here the first theoretical attempt to understand these features, focusing on the shear-thinning behaviour of these films. We analyse the profile of the dewetting film, and characterize the time evolution of the dry region radius, $R_{ d}(t)$, and of the rim height, $h_{ m}(t)$. After a transient time depending on the initial thickness, $h_{ m}(t)$ grows like $\sqrt{ t}$ while $R_{ d}(t)$ increases like $\exp{ (\sqrt{ t})}$. Different regimes of growth are expected, depending on the initial film thickness and experimental time range.
Categories: cond-mat.soft