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PO: Polymerphysik
PO 2: Grenzflächen und dünne Filme
PO 2.3: Talk
Monday, March 17, 1997, 14:50–15:10, Gg
Observation of micro-dewetting structures
— •P. M"uller-Buschbaum1, P. Vanhoorne2, V. Scheumann1, and M. Stamm1 — 1Max-Planck-Institut f"ur Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany) — 2Bayer AG, Zentrale Forschung und Entwicklung -MFP, 51368 Leverkusen (Germany)
We have studied the dewetting of thin polymer films (polystyrene) ontop of silicon substrates. With diffuse x-ray scattering and scanning-force microscopy a high in-plane resolution was achieved. Beside the well known mesoscopic dewetting structures of drops with diameters in the range of µm [1,2] we detect a further morphological feature. Inside the dewetted areas small dimples are formed ontop of an ultra-thin polymer layer. This micro-dewetting structure is in the nm-range. By comparison of the size of this new structure with molecular dimensions (radius of gyration of chains with unperturbed conformation) it is concluded that the dimples have to be formed by many chains in a collective way. Its morphology can be compared with surface structures observed in the case of end-grafted polymers [3].
[1] C.Redon, F.Brochard-Wyart, F.Rondelez; Phys.Rev.Lett. 66, 715 (1991)
[2] G.Reiter; Phys.Rev.Lett. 68, 75 (1992)
[3] D.F.Siqueira, K.Köhler, M.Stamm; Langmuir 11, 3092 (1995)