The synthesis of low molecular weight poly(hexylene oxide)-poly(ethylene oxide) (PBO-PEO) diblock copolymers as a commercially viable additive for epoxy toughening was illustrated. The amphiphilic copolymers with molecular weights between 15,000 and 20,000 g/mol, produced nanostructures that were dispersed within the epoxy with PBO as the epoxy-phobic block and PEO as the epoxy-philic block. Transmission electron microscopy (TEM) was used to characterize the resulting morphology of inclusithe in teh cured epoxy samples which were microtomed into 50-100 nm thick sections using a diamond knife. The block copolymers improved the toughness of the pure epoxy samples. The results shothehat teh low molecular weight block copolymers with string segregation can self-assemble to form structures in the epoxy matrix.