In this paper, we report on a new NMR method for exploring the interfacial region in a multicomponent polymer mixture, one component of which contains unpaired electron spins. The samples used here consist of clusters of the electron-rich polymer several hundred angstroms in size dispersed in the bulk of a support polymer. The idea is to use the method of dynamic nuclear polarization (DNP), exploiting the short range of the electron-nucleus coupling to selectively polarize nuclei close to the clusters which contain the unpaired electron spins. The NMR spectrum of these nuclei is subsequently detected. © 1988, American Chemical Society. All rights reserved.