Bayreuth 1998 – scientific programme
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PO: Polymerphysik
PO 7: Poster: Oberflächen und Grenzflächen
PO 7.3: Poster
Wednesday, March 11, 1998, 15:25–17:15, P1
Effects of confined geometry and substrate interaction on the initial stages of interdiffusion in thin polystyrene films — •Thomas Kuhlmann and Manfred Stamm — Max-Planck-Institut f"ur Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany)
The effects of confined geometry and substrate interaction on the short-time-interdiffusion in thin polymer films have been investigated by neutron reflectometry. Samples consist of alternating layers of protonated and deuterated polystyrene. The interface broadening of a thick film (4.4 Rg thick) confined between two thick films, a thinner film (0.78 Rg thick) confined between two thick ones and a thin film (0.77 Rg thick) deposited directly on a glass substrate with a thick film on top is measured as a function of time. Rg is the bulk radius of gyration, which is taken as a measure of the relative film thickness compared to the chain dimension. Samples are subsequently annealed at temperatures slightly above the glass transition temperature Tg , and the interface widths as a function of time are determined from model fits to neutron reflectivity curves. Neither a fast relaxation process at small times nor a large change of segmental dynamics as a function of film thickness are observed. Only a slight slowing down of interdiffusion dynamics for the thin film between two thicker ones is detected as well as a still slower interdiffusion for the thin film placed directly on the substrate, which is attributed to polymer - substrate interaction.