POLYMER SURFACTANT STRUCTURE AT THE AIR-WATER-INTERFACE
We report the first study of the structure of a monofunctional polymeric surfactant, hydroxyl terminated 1,4-polyisoprene, MW 3200, spread at the air-water interface from hexane solution. The system shows a highly reversible π-A isotherm and remarkable constancy in the film thickness determined by n...
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| Materiálatiipa: | Journal article |
| Almmustuhtton: |
1993
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| Čoahkkáigeassu: | We report the first study of the structure of a monofunctional polymeric surfactant, hydroxyl terminated 1,4-polyisoprene, MW 3200, spread at the air-water interface from hexane solution. The system shows a highly reversible π-A isotherm and remarkable constancy in the film thickness determined by neutron reflectivity at surface pressures above and below the classical "collapse transition". The thickness is approximately 30 Å with head group penetration into the water layer of about 10 Å and is consistent with a rigid chain conformation for the polymer. As the film is compressed, it thickens slightly indicating that the tilt of the chains increases from ca. 10° to ca. 15°, but even at relatively low pressures up to 50% of the polymer present does not contribute to the reflectivity and is probably present as multilayers. Ellipsometry measurements indicate that the same film can be transferred to a silicon substrate by Langmuir-Blodgett methods. © 1993 American Chemical Society. |
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