Single chain mobility at an interface of a liquid polymer

Interfacial diffusion of single chains of polystyrene-b-polyisoprene (PS-b-PI) at the interface between polyisoprene and its non-solvent, DMF, was studied by fluorescence correlation spectroscopy. The diffusion coefficient of PS-b-PI probe was found to be two orders of magnitude high than that in the bulk PI, indicating a lower interfacial viscosity. The experimental data also exhibit a very weak dependence of the interfacial diffusion coefficient on the molecular weight of the liquid polymer. The possible mechanism was discussed.