Kinetics of formation of interfaces between immiscible polymers

The kinetics of the formation of the interfacial width between immiscible polymer pairs are studied using neutron reflectivity. Bilayers of deuterated polystyrene (d-PS) and poly(methyl methacrylate) of high molecular weight are used. The time dependence of the formation of the interface in both cases where the thickness of the top d-PS layer is thin (less than 200 Å) and thick (greater than 1000 Å) is investigated. Following an initial rapid increase, a logarithmic dependence of the interfacial width on time is observed. We interpret this result as arising from the slow equilibration of long-wavelength capillary-wave fluctuations; comparison of our results with theory yields a value of the interfacial tension in good agreement with the self-consistent field theory prediction.