| 초록 |
Using optical microscopy (OM) and atomic force microscopy (AFM) we have measured the dewetting kinetics and layer inversion process of inverted poly(2-vinylpyridine)/polystyrene (PVP/PS) bilayer films, which were prepared by first spin coating a PS layer (40 nm thick) on a silicon wafer, followed by a PVP top layer (also 40 nm thick). The molecular weight of the PS underlayer was varied from 12,000 g/mol to 75,000 g/mol while the PVP layer molecular weight was held constant at 8000 g/mol. In comparison with the previous dewetting data on the bilayer films with similar molecular weights between PVP and PS, higher molecular weight (i.e., more viscous) PS layer at the bottom layer with similar thickness was used in this study. On annealing above the glass transition temperatures of both PVP and PS we observe that the dewetting process is slowed dramatically on the high molecular weight PS film as compared to the low molecular weight one. The reason is thought to be the deformation in the PS film near the rim of the dewetting PVP caused by the three phase contact line. |
