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DY: Dynamik und Statistische Physik

DY 45: Soft Matter

DY 45.2: Vortrag

Donnerstag, 30. März 2006, 14:45–15:00, SCH 251

Surface segregation of conformationally asymmetric polymer blends — •Semjon Stepanow and Andrei Fedorenko — Martin-Luther-Universität Halle, Fachbereich Physik, D-06099 Halle

We have generalized the Edwards’ method of collective description of dense polymer systems in terms of effective potentials to polymer blends in the presence of a surface. With this method we have studied conformationally asymmetric athermic polymer blends in the presence of a hard wall to the first order in effective potentials. For polymers with the same gyration radius R_g but different statistical segment lengths l_A and l_B the excess concentration of stiffer polymers at the surface is derived as δ ρ _A(z=0)∼ (l_B⁻²−l_A⁻²)ln( R_g²/l_c²), where l_c is a local length below of which the incompressibility of the polymer blend is violated. For polymer blends differing only in degrees of polymerization shorter polymers enrich the wall.