The nature of the interfacial interaction was examined using multiple linear regression of total scattering data, from which a P-O•••Zn interaction was suggested. This method of analysing interfacial interactions could be extended to other composite and membrane systems, where important interactions at the interface remain challenging to understand. The multiple linear regression results were consistent with 31 P NMR data and chemically sensitive electron tomography results, which showed close mixing of the two constituent phases, in which mixed, and not completely separate domains, are present. Furthermore, nanoindentation measurements on the 1:1 and 1:3 blends indicated a distribution of average moduli, indicating the presence of a well-mixed material blend with fine microstructure in both samples. Such in-depth characterisation techniques may be applied to a host of novel composites where the interface is critical to determining overall mechanical performance.