The blending of super-engineering plastics like poly(ether sulfone) (PES) with commodity polymers such as polypropylene (PP) could result in low cost materials with greatly enhanced properties, but has not been studied. In the present study, blends of PP and PES were formed by melt-mixing in the presence of modified reactive PP (mPP), with the generation of PES-mPP copolymers at the immiscible interface. It was revealed by transmission electron microscopy that daughter copolymer micelles were formed in the PP matrix and the mPP domain as a result of the copolymers' migration from the interface. It was shown that the micelles contributed to dramatic enhancement of the thermal stability of the alloys, where the size of the super-engineering plastic in the micelle core was of the order of 10 nm. Thus, the present work demonstrates a novel application of reactive processing by utilizing dispersion at the nano-scale level (similar to 10 nm) to improve polymer properties. (c) 2018 Elsevier Ltd. All rights reserved.