| Autor: |
M. Stamm, H. Motschmann, M. A. Ansarifar, Liming Dai, Chris Toprakcioglu |
| Rok vydání: |
2007 |
| Předmět: |
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| Zdroj: |
Application of Scattering Methods to the Dynamics of Polymer Systems ISBN: 9783798509528 |
| DOI: |
10.1007/bfb0116464 |
| Popis: |
We report results on adsorbed layers of polystyrene (PS)-polyethylene oxide (PEO) diblock and PEO-PS-PEO triblock copolymers at the solid/liquid interface. The volume fraction profiles of the adsorbed PS-PEO diblock copolymers at the the quartz/toluene interface determined by neutron reflectometry are consistent with a parabolic profile as predicted by theory. Ellipsometry was used to investigate the adsorption kinetics of PS-PEO diblock copolymer chains on SiO2 from toluene. The results show a rapid diffusion-controlled process, characterized by a linear increase in the adsorbed amount with the square-root of time, at the early stages of adsorption, while at late times adsorption is slow and appears to be governed by an exponential time behavior. Studies of the PEO-PS-PEO copolymer, using the surface-force apparatus, reveal conformational rearrangements for the adsorbed triblock chains between mica surfaces. When two such surfaces are in close proximity to each other, triblock chains originally adsorbed in a “loop” conformation may open into a “bridge” conformation with both PEO blocks of a given chain adsorbing onto opposing mice surfaces. This is indicated by the appearance of clearly detectable attractive forces and their evolution with compression-decompression cycles. The time evolution of these forces reflects the dynamics of the rearrangement of chains between the two surfaces. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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