Direct non-radiative energy transfer across a sharp polymer interface

A simple interfacial model system is chosen in which fluorescent donors and accepters attached to incompatible polymer chains are randomly distributed in respective phases separated by a sharp interface. Direct non-radiative energy transfer (DET) across the interface between the labeled polymer phases is observed by fluorescence decay measurements. The quantum efficiency of energy transfer (phi(ET)) is used to quantify phi(ET). We show that phi(ET), increases as the interfacial contact area between the phases increases and is inversely proportional to the diameter of the dispersed spherical donor-labeled particles. The data indicate that the degree of interpenetration at the interface is less than 2 nm.