DIRECT NONRADIATIVE ENERGY-TRANSFER ACROSS A SHARP POLYMER INTERFACE

A simple interfacial model system is chosen in which fluorescent donor s and accepters attached to incompatible polymer chains are randomly d istributed 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 quanti fy phi(ET). We show that phi(ET), increases as the interfacial contact area between the phases increases and is inversely proportional to th e diameter of the dispersed spherical donor-labeled particles. The dat a indicate that the degree of interpenetration at the interface is les s than 2 nm.