Surface enrichment-depletion duality in a binary polymer blend
Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Kraków, Poland
2 Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
Accepted: 2 July 1998
We have measured the surface segregation towards the vacuum in films of a binary mixture of deuterated (d52) —and hydrogenous (h66)— random olefinic copolymers. Here E and EE are the linear ethylene and branched ethyl ethylene groups () and , respectively. The d52 copolymer is enriched at the surface when d52 is the minority component in the blend. On the contrary, the surface is depleted in the d52 chains, when they constitute a majority of the mixture. We have determined two branches of the segregation isotherm corresponding to the enrichment and the depletion. A mean-field Cahn model describes consistently these two isotherm branches. The observed enrichment-depletion duality modifies a common viewpoint on surface segregation.
PACS: 36.20.-r – Macromolecules and polymer molecules / 68.10.-m – Fluid surfaces and fluid-fluid interfaces / 82.65.Dp – Thermodynamics of surfaces and interfaces
© EDP Sciences, 1998