title: Symmetric and asymmetric instability of buried polymer interfaces.
abstract: We demonstrate using neutron reflectometry that the internal interfaces in a trilayer system of two identical thick polystyrene layers sandwiching a much thinner (deuterated) poly(methyl methacrylate) layer 15 nm thick (viscosity matched with the polystyrene layers) increase in roughness at the same rate. When the lower polystyrene layer is replaced with a layer of the same polymer of much greater molecular mass, two different growths of the interfaces are observed. From the growth of the interface for this asymmetric case in the solid regime using the theoretical prediction of the spinodal instability including slippage at the interface, a value of the Hamaker constant of the system has been extracted in agreement with the calculated value. For the symmetric case the rise time of the instability is much faster.
authors.affiliation: Departement de Physique, Faculté des Sciences, Université Libre de Bruxelles, CP223 Boulevard du Triomphe, 1050 Brussels, Belgium.
authors.forename: J P
authors.initials: JP
authors.lastname: de Silva
authors.forename: F
authors.initials: F
authors.lastname: Cousin
authors.forename: A R
authors.initials: AR
authors.lastname: Wildes
authors.forename: M
authors.initials: M
authors.lastname: Geoghegan
authors.forename: M
authors.initials: M
authors.lastname: Sferrazza